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Optimal Design and Operation of Wastewater Treatment Plants by Prasanta K. Bhunia, Ph.D. and Michael K. Stenstrom, Ph.D., P.E. 1986

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Page 1: Optimal Design and Operation of Wastewater Treatment Plants by

Optimal Design and Operation of Wastewater Treatment Plants

by

Prasanta K. Bhunia, Ph.D.

and

Michael K. Stenstrom, Ph.D., P.E.

1986

Page 2: Optimal Design and Operation of Wastewater Treatment Plants by

I .

II .

TABE OF CONTENTS

Page

IST OF FIGURES V

IST OF TABES Vii

ACKNOWEDGMENTS viii

VITA ixABSTRACT x

INTRODUCTION 1ITERATURE REVIEW 7A. Primary Clarifier 7B. Activated Sludge Process 10C. Secondary Clarifier 16D. Anaerobic Digestion 21-

D-1 . Propionic and n-butyric acids 22D-2. Hydrogen Transfer Kinetics 26

D-3 . Inhibition 29D-4. Process Design and Process Modeling31

E. Optimization 3rd34-ESimplified Mathematical Models 35E-2. Advanced Mathematical Model 3 7

III. MODE DEVEOPMENT 41'A. Model Inputs 41B. Primary Clarifier 42C. Biological Reactor Model 48

C-1 . Nitrification 54

111

Page 3: Optimal Design and Operation of Wastewater Treatment Plants by

C-2. Oxygen Utilization

D. Secondary Clarifier Model

E. Anaerobic Digestion

E-1. Mathematical Development

E-2. Carbonate System and pH

F. Optimization Description

IV. COST EQUATIONS FOR UNIT PROCESSES

V. RESUTS AND DISCUSSION

A. Simulated Primary Sedimentation Basin Performance

B. Simulation of Activated Sludge Process

C. Dynamic Characteristics of Anaerobic Digestion122

D. Optimization 127VI. SUMMARY AND CONCUSIONS

A. Conclusions

B. Recommendations

REFERENCES

APPENDIX A

APPENDIX B

w

57

59

65

'71

79

84

94

106

106

114

137

139

142

152

157

Page 4: Optimal Design and Operation of Wastewater Treatment Plants by

IST OF FIGURES

v

Diagram

Fig. 3.6 Flux Curves

, 63

Fig. 3.7 Solids Concentration Profiles 63

Fig. 3 .8 System Information Flow Diagram 66

Fig. 3 .9 Anaerobic Digestion of Organic Wastes (Old Concept) 68

Fig. 3.10 Anaerobic Digestion of Organic Wastes (New Concept) 69

Fig. 3.11 Summary of Mathematical Model and Information Flow 85

Fig. 3 .12 Information Flow Diagram for the east Cost Design and 89Operation

Fig. 4.1 Cost Breakdown (Capital fixed operation and maintenance and 104variable operation)

Fig. 5.1 Relationship Between Efficiency (%) and SettlingVelocity, W , cms/sec 107

Fig. 5.2 Relationship Between Efficiency (%) and Settling 108Velocity, U, cms/sec

Fig. 5 .3 Relationship Between Removal Efficiency (%) and Depth, 109cms (V,W : Constant)

Fig. 5.4 Relationship Between Removal Efficiency (%) and Depth, 111

Page

Fig . 1 .1 Process System Diagram 3

Fig. 3.1 Actual and Reconstructed Biochemical Oxygen Demand 43

Fig . 3.2 Magnitude Spectrum for Biochemical Oxygen Demand 44

Fig . 3 .3 Relationship Between Pollutant Concentrations 45

Fig. 3 .4 Schematic Structured Model 51

Fig. 3 .5 Summary of Mathematical Model and Information Flow 60

Page 5: Optimal Design and Operation of Wastewater Treatment Plants by

vi

cms (V,Q : Constant)

Fig. 5 .5 Relationship Between Effluent Concentration and Depth 112with Time for Variable Flow Rate and InfluentConcentration

Fig. 5.6 Steajdy State Effluent Soluble Substrate Concentration 118gm /m

Fig. 5.7 Steady State Mass Concentrations (RXA = 0.15, RH = 0.01, 119RSD = 0.001, KT = 0.005,fs = 0.5)

Fig. 5.8 Steady State Effluent Ammonia Concentrations forVariable Solids Retention Time (SRT), Days 120

Fig. 5.9 Steady State Effluent Concentrations (Biodegradable 123Solid (BD) and Soluble Substrate (S)) for VariableSRT, Days

Fig. 5.10 Steady State Volatile Solids Destruction, Gas FlowRate (QCH4, QCO 2, and QH2), and 124Specific Growth Rate of Methanogens for Variable SRT,Days

125

126

Fig. 5.11 Steady State Un-ionized Acids Concentration (Acetic (HA),Propionic (PA), and N-Butyric Acids Concentration),and Bi-carbonate Concentration (HCO 3) for VariableSRT, Days

Fig. 5.12 Steady State Gas Production/VSS Destroyed, Total AcidsConcentration, pH, and % CH4 for Variable SRT,Days

Fig. 5.13 Optimal Design and Operating Parameters with Varying 130Oxygen Transfer Costs

Fig. 5.14 Optimal Design and Operating Parameters with Varying 132Sludge Disposal Costs

Fig. 5.15 Optimal Design and Operating Parameters with Varying 133abor Rate

Fig. 5.16 Influence of Oxygen Transfer Costs on Optimal Design andOperating Parameters for Higher SRT Systems 134

Page 6: Optimal Design and Operation of Wastewater Treatment Plants by

IST OF TABES

vii

Page

Table 2.1 Methanogenic Interspecies H2 Transfer 24

Table 2.2 Role of methanogen on Interspecies H2 Transfer 27

Table 4.1 Cost Estimates for Unit Processes 102

Table 4.2 Designed Parameters and Unit Sizes of Activated SludgeTreatment Plant

103

Table 5.1 Effluent Suspended Solids Model Parameters 113

Table 5.2 Parameters and Coefficients for Heterotrophic Bacteria 115

Table 5.3 Parameters and Coefficients for Nitrifying Bacteria 116

Table 5 .4 Steady State Results of Activated Sludge Process (CFSTR) 121

Table 5.5 Economic Parameters Used for Optimal Design and Operation 129

Table 5.6 Comparison of Optimization Cases 135

Page 7: Optimal Design and Operation of Wastewater Treatment Plants by

ACKNOWEDGMENTS

I would like to express my gratitude to Professor M .K. Stenstrom for his

encouragement, guidance, and friendship during my graduate studies at UCA and

also for serving as my graduate advisor and doctoral committee chairman . I also

wish to thank the other members of my doctoral committee, Professors R .G. ind-

berg, R.A. Mah, J.B . Neethling, and W.W-G. Yeh.

I would like to thank fellow students and office mates Sami A . Fam, Adam

S. Ng, Gail K . Masutani, Hamid Vazirinejad, Hyung J . Hwang, Hoa G. Tran,

Kevin M. Reagan, Stephen Song, Seth D . Abramson, Sam Beadles, and ynne

Cardinal for their help in clarifying topics of mutual interest .

Thanks are also due to Debby Haines who typed and retyped the seemingly

endless draft with patience and care .

viii

Page 8: Optimal Design and Operation of Wastewater Treatment Plants by

VITA

1976

B.E. (Civil Engineering), Calcutta University, India

1976-1977

Simplex Concrete Piles td ., India

1977-1979

M. Tech., Indian Institute of Technology, Kanpur, India

1979-1981

Post Graduate Research Engineer, University of California,os Angeles

1981-1982

Teaching Associate

1982-1984

Post Graduate Research Engineer, University of Californiaos Angeles

1983

The Degree of Engineer, University of California, os Angeles

1984-1985

Post Doctoral Research Engineer, University of Wisconsin

1985-1986

Project Engineer, Applied Modeling Incorporated

PUBICATIONS AND PRESENTATIONS

E.R. Christensen and P.K. Bhunia, "Modeling Radiotracers in Sediments : Com-parison with Observations in ake Huron and ake Michigan ." J. of GeophysicalResearch, AGU (In Press).

E.R. Christensen, P.K. Bhunia and M.H. Hermanson, "Forward and Inverse Prob-lems Regarding the Deposition of Heavy Metals in Aquatic Sediments . Presentedin the International Conference on Heavy Metals, Athens, Greece, 1985 .

Bhunia, P. and E.R. Christensen, "Advection-Diffusion Equation for ModelingRadionuclides in Sediments ." Paper presented at the Midwest Water ChemistryWorkshop, 1984 .

Stenstrom, M.K., Ng, A.S ., Bhunia, P., and S. Abramson, "Anaerobic Digestion ofMunicipal Solid Waste ." J. Env. Eng. Div., ASCE, Vol. 106, No. 5, Oct. 1983 .

Stenstrom, M.K., Ng, A.S., Bhunia, P., and S . Abramson, "Anaerobic Digestion ofClassified Municipal Solid Waste ." Report prepared for the Southern CaliforniaEdison Company and Cal Recovery Systems, Inc ., UCA-ENG-81-42, Oct . 1981 .

lx

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ABSTRACT OF THE DISSERTATION

Optimal Design and Operation of

Wastewater Treatment Plants

by

Prasanta Kumar Bhunia

Doctor of Philosophy in Engineering

University of California, os Angeles, 1986

Professor M. K. Stenstrom, Chair

Traditional design procedures for wastewater treatment systems attempt to

minimize total capital cost by considering steady state concepts for unit

processes and design guidelines . Recent work has minimized capital as well as

operation and maintenance costs using a single objective function and steady

state models which are flawed because plant inputs vary as much as seven fold

during a 24-hour period . Previous work using dynamic models for optimal

design does not simultaneously consider both fixed and variable costs in a single

objective function .

The objective of this dissertation was to develop a computer-based metho-

dology which considers the dynamic interactions of unit processes and includes

capital, operations and maintenance costs in a single objective function . This

methodology can aid designers by selecting optimal design and operating param-

eters for the unit processes in order to produce the minimum, total discounted

costs, while satisfying all design and operational constraints .

x

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The treatment plant model includes primary clarification, aeration, secon-

dary clarification, gravity thickening and anaerobic digestion . The dynamic

model of a primary clarifier includes a non-steady state advection-diffusion equa-

tion which considers turbulence and deposit resuspension . From this an optimal

depth to maximize efficiency was obtained . The activated sludge process model

distinguishes between particulate and soluble substrates, and calculates oxygen

requirements and sludge production from transient inputs and varying operating

strategies . These form the basis of the variable operating costs .

The goal of the anaerobic digestion model was to predict gas flow rates

and purities, volatile solids destruction, total and un-ionized volatile acids, and

pH, for different solids retention times and organic loading rates . Methane gas

production is based upon kinetics and stoichiometry which consider interspecies

hydrogen transfer, the decomposition of propionate and butyrate to acetate, and

aceticlastic methanogenesis. The revenues from methane production was sub-

tracted from the variable operating costs .

The dynamic models of unit processes were interfaced with an optimiza-

tion technique to determine optimal, independent design and operating parame-

ters conforming to the EPA effluent quality standards . The models and optimiza-

tion technique can be used to predict optimal design and operating parameters for

future wastewater treatment plants, as well as minimizing the operating costs of

existing plants .

It is concluded that the overall lifetime treatment plant cost is minimized

if capital, operation, and maintenance costs are considered in a single objective

function. It is demonstrated that this procedure produces a lower overall cost

than stepwise procedures, which may provide a least-capital cost design, but

xi

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relies upon managers to minimize operational costs after plant construction . A

sensitivity analysis of energy, labor, and sludge disposal costs was performed.

x1i

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I. INTRODUCTION

The effect of pollution on society is recognized by most citizens and has

resulted in a national commitment for the environmental clean-up . Public aw

92-500 was designed to "restore and maintain the chemical, physical and bio-

logical integrity of the nation's waters" . This law changed the enforcement pol-

icy from stream standards to source standards (i.e . dischargers were required to

limit their pollutants in accordance with EPA determined effluent limitations

irrespective of the receiving body). Under this law, industries were required to

employ the "best practicable technology" while municipalities were to provide a

minimum of "secondary treatment" by 1977 . Two thirds of all the municipali-

ties in the nation needing to upgrade their treatment systems were unable to

meet "secondary treatment" because of the magnitude of problems, and delays

in Federal funding . Therefore a considerable amount of construction of new

treatment plants and upgrading of the treatment facilities are expected in the

near future . There is still ample opportunity to improve treatment plant design

methodology to produce least cost designs .

The primary objective of wastewater treatment plant design is to provide

treatment at a minimal cost while satisfying specific requirements . In least cost

design studies, a total discounted cost is attained at the lowest possible level

while satisfying a set of constraints . These constraints include (a) a specified

effluent quality, and (b) various physical and biological constraints .

A recent trend in process research is to develop dynamic mathematical

models which can be used to simulate treatment plant operation, and can lead to

improved plant design and operation. Dynamic models are a useful tool for the

calculation of predicted operating cost for computer controlled treatment

Page 13: Optimal Design and Operation of Wastewater Treatment Plants by

systems .

The main objective of this investigation is to develop a least cost design

procedure for wastewater treatment systems, which satisfy a set of specified

constraints, and minimize life time costs . ife time cost include capital, opera-

tion and maintenance costs . This work differs from the previous work in that

the design and operation costs are considered in an integrated procedure . The

specific objectives are :

1 .

Model Development

a.

develop and calibrate a dynamic mathematical model for primary

clarifiers .

b . develop a dynamic mathematical model for activated sludge pro-

cess including the dynamics of nitrification and solid liquid

separation .

c . develop a dynamic mathematical model for the associated waste

sludge treatment subsystem, anaerobic digestion, considering the

new biological concepts of methanogenesis .

2. Determine optimal least cost design and operation for a wastewater treat-

ment system using the dynamic models coupled to a single economic

objective function which includes capital cost, fixed and variable opera-

tion and maintenance cost. Figure 1 .1 shows a typical treatment system .

For realistic model inputs, time series data were gathered and analyzed

by Fourier transform analysis to obtain the deterministic components . Inputs to

the model are constructed using the most significant Fourier coefficients, and

2

Page 14: Optimal Design and Operation of Wastewater Treatment Plants by

.U4

PRIMRY

C ARIFIER

THICKENER

R2

Y

R1

Fig

. 1.

1 Process System Diagram

AERATOR AMEa BIc

DIGESTER

III

SECONDARY

C.IRIFIER

Y

ROUTFOW

Page 15: Optimal Design and Operation of Wastewater Treatment Plants by

inputs perturbed with random noise are also considered to simulate realistic

conditions .

The model of primary clarifier used herein is a modification of steady

state model by Takamatsu et al . (1974) for non-steady state conditions . A non-

steady state model is required for realistic input conditions, i .e. variable influent

suspended solids concentration, BOD and flow rate . Turbulence and the effect

of resuspension are also considered in the model .

The activated sludge process is a complex process mediated by a mixed

population of organisms subject to varying physical and chemical characteris-

tics of influent organic load and the variability of substrate concentration and

flow rate. Conventional models for the process previously developed consider

steady state conditions with assumptions of homogeneous substrates and organ-

isms, and used zero-order, first-order or Monod (1942) kinetics for substrate

removal. These methods are not capable of describing the rapid removal of sub-

strates observed in case of the contact stabilization or step feed modifications of

the activated sludge process . Storer and Gaudy (1969) have shown that the

Monod (1942) model is not capable of predicting the lag in specific growth rate

which occurs upon an increase in substrate concentration and influent flow rate .

The model of the activated sludge process used herein is a minor

modification of the model proposed by Clift (1980) for carbonaceous substrate

removal, combined with the nitrification model proposed by Poduska (1973) . It

is a structured model which overcomes the limitations of the zero order, first-

order and Monod (1942) model . The carbonaceous model includes material

balances of stored particulate mass, active, inert, stored, non-biodegradable

mass and biodegradable and non-biodegradable soluble substrates. Material

4

Page 16: Optimal Design and Operation of Wastewater Treatment Plants by

balances for ammonia, nitrite, nitrate and the nitrifying bacteria, Nitrosomonas

and Nitrobacter are considered in the nitrification model . Material balances for

oxygen utilization are also considered for both carbonaceous substrate removal

and nitrification . The model for solid liquid separation is based upon solute flux

theory as used by Dick (1970), and combines techniques used by other

researchers (Bryant, 1972 ; Busby, 1973 ; Tracy, 1973, Stenstrom, 1976) .

The sludge treatment subsystem considered includes gravity thickening

and anaerobic digestion . The dynamic model of anaerobic digestion is

developed considering new information, indicating that methanogens do not

metabolize organic acids other than acetate and formate, with hydrogen produc-

tion and utilization is a central position (Bryant, 1979) . The dynamics of

anaerobic digestion includes material balances for biodegradable solids, non-

biodegradable solids, soluble organics, acids (propionic, n-butyric, and acetic)

and hydrogen, biodegradable solid hydrolyzers, soluble substrate oxidizers,

hydrogen consumers, and methane formers . The inhibition by un-ionized acids

incorporated in Monod (1942) kinetics is considered in the model. The model

also includes the carbonate material balance and theoretical calculation of pH .

In the past, the trend has been to design the most efficient unit processes,

each at least cost and then combine the units to form an optimum wastewater

treatment system . Erickson and Fan (1968), Naito et al . (1969), Fan et al .

(1970, 1971), and McBeath and Eliassen (1966) conducted optimal design stu-

dies of the activated sludge subsystem (aeration tank and secondary clarifier) .

Parkin and Dague (1972) demonstrated that the most efficient individual units

combined together may not produce an optimal system .

5

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A large number of studies have been reported on the least cost design of

treatment plants . Ecker and McNamara (1971), Shih and Krishnan (1969), and

Shih and Defilippi (1970) used simple biological models for the optimal design

of treatment plants, with the primary emphasis on the demonstration of a partic-

ular optimization technique, rather than working with a realistic problem . Par-

kin and Dague (1972), Middleton and awrence (1976), Berthouex (1975), and

Fan et al. (1974) developed realistic biological models oriented towards practic-

ing engineers, and used solution methods that can easily be applied to practice .

The original contribution of this dissertation is the development of a tool

which can be used to produce an optimal treatment plant design, considering

the time honored, traditional, design procedures, while simultaneously minimiz-

ing the capital and operating costs . A large fraction of the operating costs are

calculated from the dynamic treatment plant models .

6

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II. ITERATURE REVIEW

A. Primary Clarifier

Primary clarifiers in wastewater treatment plants are used to remove set-

tleable solids from wastewater. Rich (1963) and Camp (1946) considered indi-

vidual particle dynamics and demonstrated that settleable solids attain a termi-

nal velocity with respect to carrier fluid, and proposed that this terminal velo-

city is a function of particle geometry and density and the fluid density and

viscosity.

If all solids in wastewater are discrete particles of uniform size, shape

and density and settle independently, i.e. no effect on the settling velocity of

any other particles, then according to Camp (1946) and Rich (1963) the

efficiency of sedimentation is only a function of terminal settling velocity . In

the case of thickening, the particle concentration increases, causing a decrease

in clarification rate . Camp (1953) developed an empirical equation using batch

settling data to describe the performance and design of settling basins and pro-

posed that the removal of suspended solids in sedimentation basins is mainly

dependent on the surface area of the basin, and is unaffected by the depth of the

tank, except through the influence of turbulence and scour at the bottom of the

basin .

Solids in most wastewaters are not of such regular character, but hetero-

geneous in nature . Wastewater solids are flocculent, rather than discrete . Floc-

culation in sedimentation basin is due to the differences in settling velocities of

particles and the velocity gradient in the liquid caused by the eddies, resulting

from turbulence. As flocculent particles coalesce, the terminal velocity is

Page 19: Optimal Design and Operation of Wastewater Treatment Plants by

increased, with an increasing efficiency as a function of detention time . (Camp,

1946 ; Fitch, 1957) . The combined effect of flocculation and increasing solids

concentration creates a difficult problem for the mathematical model . There-

fore empirical analysis is frequently used for designing settling basins .

Hazen (1904) analyzed the settling of particles using the ideal basin con-

cept. He assumed that (a) the direction of flow is horizontal uniform velocity

throughout the settling zone, (b) the concentration of suspended particles is uni-

form over depth at the inlet of the settling zone, and (c) particles reaching the

bottom remain discrete . His work demonstrated that the efficiency of sedimen-

tation is governed by the surface area measured parallel to the direction of flow .

Hazen (1904) and Camp (1953) concluded that the efficiency of primary sedi-

mentation basin is independent of the basin depth but dependent on overflow

rate. They have also proposed that for optimum efficiency, settling tanks

should be long, narrow (minimize the effect of inlet and outlet disturbances,

cross winds, density currents and longitudinal mixing) and relatively shallow .

Hazen (1904) did not consider flocculation in his analysis .

The performance of settling basin is influenced by solids compaction

rates, particle flocculation, solids settling characteristics, solids concentration,

and inlet and outlet mixing patterns (Fitch, 1957 ; Wittwer, 1940) . Babbit and

Schlenz (1929) demonstrated that the hydraulic detention time, surface loading

rate, and suspended solids concentration have marked influence in the

efficiency of the sedimentation basin and removal efficiency increases with

increase in retention time and solids concentration . Theroux and etz (1959)

conducted tests to determine the effect of surface loading rate, basin velocity,

weir loading rates, and diurnal variation in influent flow rate and suspended

8

Page 20: Optimal Design and Operation of Wastewater Treatment Plants by

solids concentration on the performance of primary sedimentation process .

These data were used to develop an empirical equation to simulate suspended

solids removal .

Villemonte et al. (1967) tested a prototype sedimentation basin charac-

terizing the hydraulic flow regime and defined parameters such as short circuit-

ing, stagnation, eddy diffusion, and recirculation eddy . Turbulent flow, currents

induced by inertia of the incoming fluid, wind stress and density and tempera-

ture gradients, reduce efficiency . Short circuiting can be viewed as distorted

plug flow, short detention time, increased overflow rate, with reduced

efficiency. Villemonte et al. (1967) showed that real basins are neither plug

flow nor complete mixing. The effects of short circuiting can be minimized by

covering the basin (eliminates the effect of wind or heat induced currents),

adding stream deflecting baffles, influent dividing mechanisms, and velocity

dispersing feed walls. The effects of turbulence upon design and operational

theory has been investigated by Dobbins(1944), Camp(1946), Goda(1956), and

El- aroudi(1969) .

The empirical steady state model proposed by Smith (1969) predicts

removal efficiency as an exponential function of overflow rate . function of a

settler. Equation 2.1 is typical of empirical models used to describe primary

clarifiers .

Mr = Mt f (Ql

where,

MMr

total concentration of settleable materials,total concentration of settleable solids inthe outflow of the settler,total concentration in the inflow,

9

Page 21: Optimal Design and Operation of Wastewater Treatment Plants by

inflow rate,area of the settler .

ryant (1972) developed a dynamic mathematical model considering

both mixing and clarification. The hydraulic mixing regime is modeled as a

series of complete mixing compartments, a technique commonly used in chemi-

cal engineering (evenspiel, 1965 ; Himmelblau, 1968) . ryant (1972) approxi-

mated the mixing phenomena by considering five continuous stirred tank reac-

tors in series, which leads to a mixing regime between a plug flow and complete

mixing .

Settling basins are operated as continuous flow units and in order to deal

with the time variation of flow rate and concentration, a dynamic model has to

be developed. Takamatsu et al . (1974) developed a steady state mathematical

model considering deposit scouring for the design of primary clarifier . Deposit

scouring was treated by a diffusion type equation by introducing a parameter at

the bottom boundary condition which described the rate of scouring and

resuspension . The model developed later builds upon this concepts .

. Activated Sludge Process

The activated sludge process oxidizes organic matter, both soluble and

particulate in a semi-controlled environment with the presence of a mixed cul-

ture of organisms. The oxidation process removes nutrients and organics and

returns the product of metabolism to the liquid .

Organics + nutrients + oxygen + acteria

----> New bacterial cells + residual organics

and inorganics + carbon-dioxide + water

+ energy

10

Page 22: Optimal Design and Operation of Wastewater Treatment Plants by

The actual oxidation is much more complex due to varying population of mixed

culture and complex characteristics of organic matter .

The first mathematical model for continuous culture of micro-organisms

was developed by Monod (1942). The purpose of the model is to describe the

removal mechanism of a single substrate by a given bacterial population in a

homogeneous medium. Monod kinetics, along with a first-order decay

coefficient, adequately describes the steady state conventional activated sludge

process over a limiting period .

Wastewater received by treatment plants contain a wide variety of sub-

strates and operate with a heterogeneous mass, but the substrate and sludge

mass have been considered homogeneous in the past . The Monod model does

not predict the correct response with the process is subjected to time varying

inputs. Reasons for this are the time lag in microbial growth and rapid uptake

of exogenous substrate in the contact stabilization modification of the activated

sludge process. More advanced models separate the microbial mass into dif-

ferent components such as stored reserves, active mass, particulate and inert

mass.

Models used by Fan et al . (1974) and Kuo et al . (1974) include equations

for dissolved and suspended components of substrates . Kinetics for growth

upon suspended solids were considered as first-order, and dissolved substrate

kinetics included an additional term in the denominator, proportional to

suspended solids concentration, in order to reflect their masking effect .

The mathematical description of lag phase was first presented by Powell

(1967). The incorporation of lag phase is essential for simulating the dynamic

11

Page 23: Optimal Design and Operation of Wastewater Treatment Plants by

response of an activated sludge process and one method for consideration of the

lag period is to structure the microbial mass .

Most wastewater contains both soluble and particulate organic and inor-

ganic matter. Heukelekian and almat (1959) proposed that domestic wastewa-

ter contains more organic carbon in colloidal and suspended form than the dis-

solved form. Hunter and Heukelekian (1965) found that particulate fraction is

66% to 83% organic and contributes 58% and 63% of volatile solids for domes-

tic wastewater. The COD to volatile solids ratio for the particulate fraction is

approximately 1 .5 to 1 .0 while for the soluble fraction varies from 0 .6 to 0.8 to

1 .0 .

The composition of the sludge in the activated sludge process depends

upon the characteristics of wastewater and design and operational characteris-

tics of the process . Researchers have demonstrated that the potential activity of

the sludge in the activated sludge process is only a small fraction of its total

capacity. Garrett and Sawyer (1952) demonstrated that sludge in conventional

plants react at only 4% of its maximum capability . Sludge consists of viable

organisms, inert organic matter from death and lysis of cells, volatile solids and

non-volatile solids from influent wastewater. The number of viable organisms

and volatile solids in the sludge decreases as the sludge age increases, and the

decrease is due to death of organisms, accumulation of inerts, depletion of par-

ticulate organic substrates and predator activity . Conventional and low rate

sludges consists largely of non-viable solids . Weddle and Jenkins (1971) pro-

posed that the viable heterotrophic organisms concentration in sludge is

between 10% to 20%. Upadhyaya and Eckenfelder (1975) measured the biode-

gradable fraction of mixed liquor grown on skim milk to find the viable frac-

12

Page 24: Optimal Design and Operation of Wastewater Treatment Plants by

tion . The biodegradable fraction of MVSS at mean cell detention time of

12.1 days was found to be 0.67. iodegradable fraction increases with an

increase in F/M ratio but decreases with an increase in sludge age . Considering

activated sludge with 85% volatile matter at mean residence time of 10 days,

Adams and Asano (1978) estimated that approximately 60% of the total mass of

sludge in a conventional plant can be considered biodegradable material, both

cells and entrapped substrate . They have also suggested that the active fraction

in sludge is between 0 .2 to 0.3 at a sludge age of 10 days . Tench (1968)

estimated the active fraction to vary from 0 .2 to 0.37, and based his results on

nitrogen content. Kountz and Fourney (1959) demonstrated that 23% of sludge

is non-oxidizable and the accumulation of non-oxidizable sludge will be

minimum only when there is sufficient nitrogen in the system .

The rate of transfer of substrate from the liquid is greater than the rate at

which substrate is metabolized by floc . Ruchhoft and utterfield (1939)

presented data for rapid removal of substrate and proposed that substrates are

stored as internal reserves, or as adsorbed material to floc surfaces by various

metabolisms. These findings show little direct relationship between specific

growth rate and concentration of substrate in the liquid, and suggests that the

Monod model may not be directly applicable to the activated sludge process .

Eckenfelder (1963) used first-order kinetics for rapid removal of soluble

substrates by activated sludge floc. Katz and Rohlich (1956) and Siddiqi et al .

(1966) proposed that some saturation value of initial removal step must occur .

Eckenfelder's model does not predict this result . Placak and Ruchhoft (1947)

concluded that initial substrate removal is dependent on the specific substrate .

Therefore, some soluble substrates follow rapid removal phenomena and others

13

Page 25: Optimal Design and Operation of Wastewater Treatment Plants by

may be metabolized directly from the liquid phase . Kuo et al. (1974) observed a

lower rate of removal of dissolved substrates when particulate matter was

present in the aeration tank, indicating the masking effect of active sites on the

floc by particulate substrates .

The removal of particulate substrates by activated sludge is also very

rapid, but degradation is very slow (Gujer, 1981). Mechanisms for removal are

coagulation, entrainment, and adsorption (Weston and Eckenfelder, 1955) .

Adam and Asano (1978) proposed that the exopolymer component of activated

sludge is a polyelectrolyte, effective in flocculation and removal of particulate

matter involves adsorption and entrapment . anerjee (1968) demonstrated that

hydrolysis of colloidal substrates begins immediately upon contact with

activated sludge floc. Weston and Eckenfelder (1955) showed that soluble sub-

strate was initially removed until some initial OD was reached, thereafter the

removal rate was sharply decreased .

Jones (1971) hypothesized that removal mechanisms for soluble and par-

ticulate substrates are different. Mechanisms can be summarized as (a) adsorp-

tion and entrapment of particulate matter which can be approximated by first-

order kinetics with a rate coefficient of the order of 10 hr -1 , (b) adsorption of

soluble substrate by first-order kinetics with a rate coefficient of 0 .1 to

0.20 hr-1 , and (c) hydrolysis of entrapped and adsorbed particles to soluble

material which is then degraded as adsorbed soluble material . Gujer (1981)

proposed that all particulate substrates do not degrade at a constant rate and

degradation rates may vary from slow to fast for large to small particles to dis-

solved organic compounds . The degradation rate also depends on mean cell

retention time of activated sludge process . Jacquart et al . (1973) proposed a

14

Page 26: Optimal Design and Operation of Wastewater Treatment Plants by

mathematical model considering substrates as dissolved and un-dissolved . The

un-dissolved volatile matter is converted to reserves of un-dissolved origin by

entrapment and reserves of dissolved and un-dissolved origins are transformed

into active mass using Monod type saturation function but constants are dif-

ferent for different types of reserves . This model predicts both the rapid uptake

mechanism and lag phases. Jacquart et al . (1973) did not consider the inert bio-

logical mass in their mathematical model . Takahasi et al. (1969) found that

higher F/M ratio increases bacterial cells ability to store nutrients and use these

stored materials when F/M ratio is low. They have also found that the addition

of soluble substrates to an activated sludge previously in contact with only par-

ticulate matter renew the activity . This was due to new sludge which was

formed rapidly upon addition of soluble substrates . Stabilized sludge has a very

low concentration of storage products which will tend to accelerate the removal

rate during contact with substrate .

A structured steady state model developed by Tench (1968) considered

mass into three components; an adsorbed oxidizable, an active, and biologically

inert . lackwell (1971), usby (1973) and Stenstrom (1975) developed the

structured dynamic mathematical model for activated sludge . usby (1973)

modified lackwell's equation by incorporating Monod type saturation func-

tion to account for the extracellular substrate concentration . Their models did

not distinguish between soluble and particulate substrate, and assumed that all

of the substrate passes through storage prior to metabolism .

Ekama and Marais (1979) studied the dynamic behavior of activated

sludge and demonstrated that lackwell's model provides significant improve-

ment over unsaturated models for predicting transient responses. However,

15

Page 27: Optimal Design and Operation of Wastewater Treatment Plants by

they agreed that consideration should be given to extracellular substrate concen-

tration. The modification of the model considering soluble and particulate sub-

strates provided the best fit to their experimental data .

Nitrification is an important function of the activated sludge process .

Nitrogenous compounds not only accelerate eutrophication, it also exert a

significant oxygen demand . Nitrification can occur in the presence of carbona-

ceous oxygen demand if certain conditions exit . The necessary conditions are

at least 0 .5 to 1 .0 mg/l of dissolved oxygen concentration and operation above

the washout sludge age of nitrifiers .

Downing and Co-workers (1964) proposed the first model for

nitrification. They used batch data and Monod kinetics to determine the kinetic

coefficients . Poduska (1973) used Monod saturation kinetics and verified the

model using the laboratory scale experimental data. He developed mass bal-

ances on ammonia, nitrite, nitrate and nitrifying species of the genera Nitroso-

monas and Nitrobacter. Poduska's model is used here and discussed later .

Poduska's work should be consulted for extensive literature review on

nitrification .

C. Secondary Clarifier

Excellent removal of organic matter from municipal and industrial

wastewater by activated sludge process is possible only by proper design and

operation of secondary clarifiers. It has three distinct purposes (a) thickening of

biological solids for recycle (b) clarification of effluent and (c) storage of bio-

logical mass in the settler . Coe and Clevenger (1916) were the first to provide a

comprehensive description of thickening and design of secondary clarifier . The

16

Page 28: Optimal Design and Operation of Wastewater Treatment Plants by

steady state model. was developed to predict solids handling capacity based on

batch settling tests . ike Coe and Clevenger (1916), Kynch (1952) considered

the upward propagation of zones of higher concentration with lower solids han-

dling capacity, and presented a theoretical and more complicated interpretation

of the batch settling process . Edde and Eckenfelder (1968) proposed an empiri-

cal, steady state model to relate the underflow concentration to the influent

solids concentration and flux. Rex Chainbelt Incorporated (1972) developed a

mathematical model to predict the solids concentration of both the underflow

and overflow of a secondary clarifier, but their model failed to account for the

effects of both influent flux and underflow rate on underflow solids concentra-

tion.

ryant (1972) is the first to develop a dynamic model for continuous

thickening process . y implementing Kynch's assumptions regarding the zone

settling, ryant (1972) derived a partial differential equation around a differen-

tial volume in a secondary clarifier .

ac

aGs aC=-(U+

) .at

ac

az

(2.2)

where,

U = underflow velocity, (IT),

GS =batch flux, (MI 2T) = C*V

C = suspended solids concentration, (MI 3),

VS =settling velocity, (JT),

z =vertical distance, (),

t = time, . (T).

The above equation contains two unknowns, C and Vs . A second equation

17

Page 29: Optimal Design and Operation of Wastewater Treatment Plants by

describing settling velocity is required for the solution . ryant solved this

equation by lumping parameters to yield a set of ten elements defined by ordi-

nary differential equations . Settling velocity in a secondary clarifier is a func-

tion of solids concentration, time, distance, depth, and perhaps partial derivative

of concentration and velocity with respect to distance. The lumped parameter

approximation can lead to erroneous results .

Tracy (1973) developed a dynamic continuous thickening model similar

to that of ryant's (1972) . Tracy was one of the first to evaluate the limitations

of the model by means of laboratory thickening experiments . For the solution

of continuity equation using a computer, Tracy assumed that solids, upon enter-

ing the thick sludge blanket, are concentrated instantaneously to the limiting

solids concentration . The limiting concentration was calculated by differentiat-

ing an empirical equation describing a solids flux curve . The results of this

assumption is that the boundary condition for the surface of the thick sludge

blanket is the limiting concentration . This resulted in a simulation error when

limiting concentration is changed due the change in operational conditions .

Tracy proposed that this simulation error is negligible . He observed the tran-

sient response of the thickener and proposed that layers of varying solids con-

centration tend to propagate through the sludge blanket as an distinct identity .

Dennis (1976) developed a dynamic continuous thickening model with the

assumption that limiting flux governs the transport of solids within the settler .

aboratory investigation showed that the flow of the displaced fluid through the

sludge blanket is an important parameter in affecting the solids flux transmitted

within the thickener. A liquid mass balance was incorporated in the model to

take into account the effect of displaced fluid. A force balance, based on batch

settling data, was considered in the model to accommodate the effect of

18

Page 30: Optimal Design and Operation of Wastewater Treatment Plants by

compressive stresses on subsidence rate of solids .

The second function of a secondary clarifier is clarification . The

clarification efficiency of the secondary clarifier has great influence on treat-

ment plant efficiency because particulate fraction contributes a major portion of

effluent OD. Pflantz (1969) conducted a study on secondary sedimentation

and proposed that the effluent concentration is dependent on overflow rate, the

concentration of feed solids to the settler, sludge settleability monitored by

sludge volume index (SVI), wind, and temperature . Pflantz found that the con-

centration of suspended solids in mixed liquor is the most important factor for

the clarity of the effluent . ut he recommended that secondary clarifiers be

designed on the basis of mixed liquor volatile suspended solids (MVSS) con-

centration as well as hydraulic loading . For low MVSS values, the required

volume of the aeration basin is large, while for the secondary clarifier, it is

small. For high MVSS values, the situation is reversed . Direct relationship

between MVSS and effluent suspended solids concentration obtained from

experiments by Tuntoolavest (1980) suggests that the low MSS is the key to

the optimal design of activated sludge process .

Chapman (1982) developed a regression equation using his pilot plant

data which is a function of MSS concentration, side water depth, and feed

flow rate. The equation of effluent suspended solids concentration from the

secondary clarifier is

XEFF = - 180.6 + 40.3*MSS + 133.24*Qa /A

+ SWD (90.16-62.54*Qa /A )

where,

19

(2.3)

Page 31: Optimal Design and Operation of Wastewater Treatment Plants by

XEFF = effluent suspended solids concentration, mg/l,

NESS = mixed liquor suspended solids concentration, g/l,

Qa/A = clarifier feed flow rate, m/h,= Qt lA + Qr lA

Qt/A = plant inflow per unit surface area, m/h,

Qr /A = recycle flow per unit surface area, m/h,

A = surface area of the secondary clarifier, m 2,

SWD = side water depth, m .

Cashion (1981) proposed that effluent with low suspended solids concentration

is possible for two operating conditions (a) SRT of about 2 days and HRT of

about 12 hours, and (b) SRT of 8 days and HRT of about 4 hours . The

overflow rate has very little effect on effluent suspended solids concentration .

A statistical analysis effluent data from 29 plants resulted the following

relationship between OD 5 and effluent suspended solids concentration:

where,

OD 5 = 8.8 + 0.61 * XEFF .

OD 5 = 5 day biological oxygen demand, g /m 3 ,

XEFF = effluent suspended solids concentration, g lm 3 .

Dick (1970) indicated that 1 mg of suspended solids is approximately 0 .6 mg/l

of OD5 where as Keffer's (1962) 20 years of data concluded a ratio of 0 .55

mg of OD 5/mg of suspended solids .

20

(2.4)

Page 32: Optimal Design and Operation of Wastewater Treatment Plants by

D. Anaerobic Digestion

The anaerobic digestion process degrades complex organic matter in the

presence of a mixed culture of microbial mass under a controlled environment

and forms carbon-dioxide and a useful end-product, methane gas. It is widely

used for stabilizing municipal waste sludge, and there is an increasing interest

in using this process for treating industrial waste which contains high concen-

trations of organics . There are significant advantages of anaerobic digestion

over other processes used for this purpose, among these are a high degree of

waste stabilization, low net microbial mass, low power requirements, formation

of a usable product, methane gas and digested sludge which can be used as soil

conditioner. ut even with all these advantages, the process has not, in general,

suffers because of its poor record of process stability .

Anaerobic digestion, a complex process hydrolyzes complex insoluble

organic matter by extracellular enzymes; the hydrolysis products are fermented

to volatile fatty acids by a group of facultative and anaerobic bacteria, known as

'acid formers', and finally the acids are converted to methane and CO 2 by obli-

gate anaerobic bacteria and methanogens (Graef, 1972 ; Hill and arth, 1977) .

Recently ryant et al. (1976, 1977, 1979), McInerney et al . (1979, 1980,

1981), Mah et al. (1977), Wolin (1976), and oone and Smith (1978) proposed

a new theory for anaerobic digestion . As before non-methanogenic bacteria

degrade organic matter to form volatile fatty acids (acetic, propionic, n-butyric,

valeric and caproic), H2, and CO2. Then fatty acids are converted to acetate

and methane by syntrophic association with H2producing acetogenic bacteria

and methanogens . This hypothesis is based on the work of ryant et al . (1967)

with Methanobacillus omelianskii, originally believed to be pure culture, that

21

Page 33: Optimal Design and Operation of Wastewater Treatment Plants by

degrades ethanol to acetate and methane in a symbiotic association of methano-

gens with H2producing bacteria .

D-1. Propionic and n-butyric acids

Obligate proton-reducing acetogenic bacteria are involved in oxidation

of fatty acids of even and odd numbered carbons to acetate and H2 and pro-

pionate, as shown in equations 2.5 and 2.6 . Decarboxylation of propionate to

acetate, CO 2, and H2 is shown in equation 2.7 .

CH 3CH 2CH 2000 + 2H20-4 2CH 3COO - + H+ + 2H 2

0

AG = + 11 .5 K cal /reaction(2.5)

CH 3CH2CH2CH2000 + 2H20

-~ CH 3000 + CH 3CH2000

+H++2H2

0

OG = + 11 .5 K cal /reaction

CH3CH2000 + 3H2O -4 CH 3000 +HC03 +H+ + 3H 2

0

OG = + 18.2 K cal /reaction(2.7)

Sparging experiments developed by oone and Smith (1978) demonstrated the

ability of obligate proton reducers to produce H 2 from propionic and n-butyric

acids, but not from acetic acid . They have also shown that propionate and

butyrate enrichments utilize H 2 without a lag, and when they are vigorously

sparged with C0 2, H2 replaces methane as a product; this does not happen in

acetate enrichments. Therefore, large amounts of H2 can be produced during

22

Page 34: Optimal Design and Operation of Wastewater Treatment Plants by

dissimilation of propionate and butyrate, and large amounts of H2 can be oxi-

dized in the production of methane in these enrichments .

Short term exposure to H2 strongly inhibits the degradation of pro-

pionate and butyrate but not acetate by enrichments ( oone and Smith, 1978)

and in anaerobic digestion of domestic sludge (Kasper and Wuhrmann, 1978) .

So the oxidation of propionic and butyric acids is probably dependent on H2

removal, which might be expected during interspecies H 2 transfer. Therefore,

for thermodynamically favorable conditions of equations (2 .5), (2.6), and (2.7)

the partial pressure of H2 should be maintained below 10 -5 and 1076 atmo-

sphere for propionate and butyrate respectively (McInerney and ryant, 1980).

The existence of obligate proton reducers was verified by the growth of

the following co-cultures of two different organisms reported by ryant and his

co-workers for degradation of one of these substrates (Table 2.1) .

The sulfate-reducing bacteria have implicated the propionate oxidation

in anaerobic systems. A recent study by oone and ryant (1980), documented

a species of bacteria (Syntrophobacter wolinii) which in co-culture with H2

utilizing sulfate reducers (Desulfovibrio Sp.) degraded propionate and sulfate to

acetate, sulfide, and CO 2. When M. hungatei was added to the culture with the

absence of sulfate, the medium produced acetate, methane, and CO 2.

McInerney et al. (1979) isolated a species of anaerobic bacterium that

degrades butyrate to acetate and H2 in syntrophic association with either an

H2utilizing methanogen or H2utilizing Desulfovibrio . This organism, called

Syntrophomonas wolfei, oxidizes saturated fatty acids (butyrate through

octanoate) to acetate or acetate and propionate with the proton serving as the

23

Page 35: Optimal Design and Operation of Wastewater Treatment Plants by

Tabl

e 2.

1 Methanogenic InterspeciesH2

Transfer

Non-methanogens

(H2producers)

Subs

trat

esH2

using

bact

eriu

mMixed

culture

prod

ucts

Reference

Synt

roph

obac

ter

Propionate

Desulfovibrio Sp

.Ac

etat

eoone and

wolinii

andsul

fate

andH2S

ryant(1980)

Propionate

DesulfovibrioSp

.and

Acetate

oone and

Meth

anos

piri

llum

hun

gate

iandCH4

ryant(1980)

Synt

roph

omon

asut

yrat

eMe

than

ospi

rill

um h

unga

tei

Acet

ate

McInerne

ywolfei

andCH

4et al.

(19

79)

Vale

rate

Meth

anos

piri

llum

hun

gate

iAc

etat

e,McInerney

CH4and

et al.

(19

81)

Propionate

Page 36: Optimal Design and Operation of Wastewater Treatment Plants by

electron acceptor. ut the degradation of butyrate is thermodynamically more

favorable when it is coupled with H2 utilization by a sulfate reducer rather than

a methanogen because the reduction of sulfate to sulfide by H2 is thermo-

dynamically more favorable than reduction of CO2 to methane by H2 ( ryant

et al. 1977 ; Thauer et al . 1977) . y co-culturing Syntrophomonas wolfei with

methanogens, McInerney et al . (1979,1981) showed that H 2 is the electron sink

product and the methanogen present used only H2 for growth and methano-

genesis .

The isolation of Syntrophomonas wolfei (McInerney et al. 1979, 1981)

and Syntrophobacter wolinii ( oone and ryant, 1980) via co-culture with H2

using bacteria provided direct evidence for the existence of obligate proton

reducing bacteria ( ryant, 1976) and for its role in the complete anaerobic

degradation of organic matter to C02 and CH4 (Zehnder, 1978 ; Kasper and

Wuhrmann, 1978) .

The continuous anaerobic digestion of wastes to CH4 and CO 2 is depen-

dent on the role of hydrogen on conversion of acetate to methane and COT

Smith and Mah (1978) and Zinder and Mah (1979) found that H2 inhibits

methane formation from acetate, resulting in an accumulation of acetate .

Recently oone (1982) experimentally showed that the acetate level in anaero-

bic digestion is higher, apparently due to increased H2 and inhibition of acetate

dissimilation.

2 5

Page 37: Optimal Design and Operation of Wastewater Treatment Plants by

D-2. Hydrogen Transfer Kinetics

Hydrogen is a major product of fermentation of organic matter in an

anaerobic ecosystem, e .g. anaerobic digestion . Groups of bacteria present in

anaerobic systems contain hydrogen-using micro-organisms (hydrogenotrophs)

as well as hydrogen-producing microorganisms (hydrogenogens) . Most

methanogens (hydrogenotrophs) obtain energy for growth via reduction of CO 2

in the presence of H2 to form methane .

4H2 + HCO 3 +H+ -4 CH4 +3H20

0

OG = - 32.4 k cal /reaction(2.8)

In a mixed culture system (non-methanogenic and facultative anaerobes) in the

presence of appropriate enzymes, H2 is a major end product . Methanogens are

completely dependent on non-methanogenic species for their supply of H2

because the products (H 2 and CO 2) of the energy metabolism of hydrogeno-

gens (non-methanogens) are the substrates for the growth of hydrogenotrophs

(methanogens) (Table 2.2) . H 2 formation is only thermodynamically favorable

if the H2 concentration is maintained at a very low level by removing it from

the system ; in the digester . THis is normally achieved by the methanogens .

This phenomenon is known as 'Interspecies Hydrogen Transfer .' One explana-

tion of this is illustrated by the following reactions .

1 .

Propionate oxidizing acetogenic bacterium

CH3CH2000 + 3H2O

-* CH3000 +HCO3 +H+ + 3H2

26

Page 38: Optimal Design and Operation of Wastewater Treatment Plants by

Hydrogenogens only

ORGANIC SU STRATES

VOATIE ORGANIC ACIDS

(e .g . Propionate, n-butyrate,Caproate, Valerate etc .), and

NEUTRA END PRODUCTS

Hydrogenogens and Hydrogenotrophs

ORGANIC SU STRATES

(Hydrogenogens)

VOATIE ORGANIC ACIDSH2 + C02

(Hydrogenogens)

H2 + C02

(Hydrogenotrophs)

ACETIC1ACID

CH4 + C02

(Aceticlastic Methanogens)

I

CH4 + C02

Table 2 .2 Role of Methanogens on Interspecies H2 Transfer

27

Page 39: Optimal Design and Operation of Wastewater Treatment Plants by

0

AG = + 18.2 k cal /reaction

2.

utyrate oxidizing acetogenic bacterium

CH3CH2CH2000 + 2H2O -~ 2CH 3000 +H+ + 2H2

0

AG = 11 .5 k cal /reaction

3 .

H2 utilizing methanogens

4H2 + H + + HCO3 --+ CH4 +3H20

0

AG = -32.4 kcal /reaction

Add 1 and 3. Syntrophic Association

4CH3CH2000 + 3H2O

-+ 4CH3000 + HCO3 + H+ + 3CH4

0

AG = - 24.4 k cal /reactionAdd 2 and 3 . Syntrophic Association

2CH 3CH2CH 2000 + HCO 3 + H2O -4 4CH3000 + H+ CH4

0

AG = - 9.4 k cal /reaction

where0

AG = change in free energy (Thauer et al., 1977).

28

(2.10)

(2.11)

(2.12)

(2 .13)

According to Hungate (1967) the partial pressure of H2 is low for an

active methane formation in an anaerobic environment and the reported partial

pressure ofH2 is about 3 x 10-4 atmosphere for the bovine rumen ecosystem.

Page 40: Optimal Design and Operation of Wastewater Treatment Plants by

A large negative change in free energy in the equilibrium of the reaction,

equation (2.8) demonstrates that the reduction of CO 2 favors the use of H2 and

formation of CH4. The rapid use of H2 by methanogens maintains a very low

partial pressure of H2, even though a large amount of H2 is produced. Accord-

ing to Smith and Mah (1966), Mah et al . (1977), methanogens degrade acetate

according to the following equation in the absence of exogenous electron

acceptors (0 2, NO 3 , SO42 ) .

CH3C00-+H20 -4 CH4 + HCO 3

0

OG = - 7.4 k cal /reaction(2.14)

In case of anaerobic municipal waste digestion, acetate is the main pre-

cursor of methane (Jeris and McCarty, 1965; Smith and Mah 1966) where the

acetate is directly converted to methane and CO 2 by aceticlastic bacteria .

D-3. Inhibition

Inhibition is the impeding property of a reaction caused by a higher con-

centration of some troublesome substances . It has been observed in anaerobic

digestion by many investigators, among them are Andrews (1969), McCarty

(1964), and uswell (1936). McCarty (1964) proposed that volatile acids are

inhibitory to methane bacteria through a reduction in pH and this inhibition is

relieved by maintaining the pH near neutrality . ut uswell (1936) mentioned

that volatile acids concentration greater than 2000 to 3000 gm /m 3 is inhibitory

regardless of pH and this inhibition can be relieved by reducing organic loading

or diluting the reactor content. Data from the bench scale study by Andrews

(1969) resolved the 'volatile acids controversy' by considering inhibition due to

29

Page 41: Optimal Design and Operation of Wastewater Treatment Plants by

greater concentration of un-ionized volatile acids (> 0 .007 gm /m 3) . Since the

un-ionized acids concentration is a function of pH and total acids concentration,

both are important . Pure culture studies by evine and Fellers (1940) and

Rahn and Conn (1944) led to the conclusion that the un-ionized form of a sub-

strate is inhibitory to microorganisms . Andrews (1969) proposed that un-

ionized volatile acids are rate limiting at low concentrations and inhibitory at

high concentrations and formulated an inhibition function which is analogous to

enzyme inhibition equation (Dixon and Webb, 1964) .*

€ = €l(1 .+(KS /HS)+(HS /KI ))

where,

=

specific growth rate, 1/days,

=

maximum specific growth rate, 1/days,

KI

-

inhibition constant, moles/liter,

HS

=

un-ionized substrate concentration,

moles/liter,

KS

=

saturation constant, moles/liter .

Fermentation of organic waste forms acetic, propionic and butyric acids

and H2 as intermediates, and C02 and CH4 as end products . oone and

Smith's (1981) experiment showed large amounts of hydrogen production dur-

ing dissimilation of propionate and butyrate, and large amounts of H 2 oxidation

in the production of methane. McInerney et al . (1981) demonstrated that an ini-

tial partial pressure 0 .8 atm. of H2 completely inhibits butyrate degradation by

the Syntrophomonas wolfei in co-culture with M. hungatei . Acetate dissimila-

30

(2.15)

Page 42: Optimal Design and Operation of Wastewater Treatment Plants by

tion is slightly inhibited by molecular hydrogen, while propionate and butyrate

degradation is completely stopped (Boone and Bryant, 1980) . They have also

showed that higher sulfide concentration inhibits propionate degradation by

repressing the growth of the co-culture of Syntrophobacter wolinii Desulfovi-

brio Sp., with the main effect on Syntrophobacter wolinii. Zinder and Mah

(1979), and Boone (1982) proposed that hydrogen inhibits methane formation

from acetate . Therefore, in the presence of increased H2 concentration

methanogenesis will be repressed, and acetic, propionic, and butyric acid con-

centrations will accumulate with a drop in pH . So the maintenance of very low

hydrogen concentration is essential for the dissimilation of volatile acids .

D-4. Process Design and Process Modeling

Kinetic failure of anaerobic digestion results from the continuous reduc-

tion of solids retention time until limiting solids retention time exceeds the

inverse of maximum specific growth rate causing a washout microbial mass .

Failure is due to an increased concentration of short and long chain fatty acids,

evidenced by the near cessation of CH4 production and decreased stabilization

rate. McCarty (1966) and O'Rourke's (1968) research on digestion of primary

domestic waste sludge indicated that the fermentation of short and long chain

fatty acids to methane and CO2 is the rate limiting step . Ghosh et al. (1975),

Kasper and Wuhrmann (1978), Pretorius (1969), Bryant (1976), and Boone

(1982) proposed that the rate-limiting step in anaerobic digestion of organic

matter is the methanogenic reactions involving reduction of CO 2 with H2 and

degradation of acetate. Conversion of acetate to methane and C0 2 is more

rate-limiting than reduction of CO 2 with H2 to methane (Kasper and

Wuhrmann, 1978).

31

Page 43: Optimal Design and Operation of Wastewater Treatment Plants by

awrence (1971) studied the application of process kinetics on the

design of anaerobic processes with the consideration of three main volatile

acids, acetic, propionic, and butyric acids formed as intermediates in the fer-

mentation of organic matter to CH4 and CO 2 . These three main acids were

chosen because (a) acetic acid is the precursor of about 70% of methane forma-

tion in anaerobic digestion of domestic waste sludge (Smith and Mah, 1966 ;

McCarty, 1964), (b) acetic and propionic acids together are the precursor of

85% of the methane formation (McCarty, 1964), and (c) butyric acid is the pre-

cursor of an additional 8% of the methane formed (Smith et al . 1970) . The

stoichiometry of fermentation of these volatile fatty acids used by awrence

(1971) is shown in the following equations .

Acetic Acid :

CH3000 +H20

-, CH4 + HCO sPropionic Acid :

_ 1

3

1CH 3CH2000 + - H20 -4 CH 3000 + - CH4 + - C0 22

4

4

(2.17)

Butyric Acid

_

1

1CH CH CH COO + HCO

-~ 2CH COO + - CH + - CO3

2

2

3

3

2

4 2

2(2.18)

awrence and McCarty (1969) determined kinetic coefficients for the stabiliza-

tion of acetic acid to methane and dissimilation of propionic and butyric acid .

Values of growth coefficients were computed on the basis of mg of biological

solids per mg of substrate COD converted for energy, i .e. to methane . Values

of decay coefficients were considered constant .

(2.16)

32

Page 44: Optimal Design and Operation of Wastewater Treatment Plants by

Most mathematical models used for the design and operation of anaero-

bic digestion, even today are steady state models . These models include acid

formation and removal, as well as methane formation . Monod kinetics have

been used and shown to be satisfactory for steady state design and operation

(Andrews and Graef, 1971 ; awrence and McCarty, 1969 ; Fan et a1, 1973) .

Modeling of conventional anaerobic digestion is based on the assumption that

the stoichiometry of volatile acids concentration is approximated by the

stoichiometry for acetic acid conversion (Andrews and Graef, 1971) .

Steady state mathematical models cannot be used for the prediction of

performance during start up operation or under transient conditions resulting

from the change in inputs. The reputation of anaerobic digestion as an unstable

system encouraged the development of dynamic mathematical models to obtain

better control procedures for preventing process failure and for optimizing pro-

cess performances . Dynamic models should also be used for improved process

design (decreased need for oversizing) because it would allow the comparison

of different versions of process in terms of process stability .

Graef (1972) developed a dynamic mathematical model of anaerobic

digestion to investigate control strategies and process stability . The dynamic

model considered (a) an inhibition function for specific growth of methanogens,

(b) un-ionized fractions of volatile acids are rate limiting at low concentration

and inhibitory at high concentration, (c) un-ionized acids concentration is a

function of both the total concentration of acids and pH, and (d) interaction in

and between the liquid, gas and biological phases of digestion . This interaction

permits to predict the dynamic response of pH, volatile acids concentrations,

alkalinity, gas flow rate, and gas composition .

33

Page 45: Optimal Design and Operation of Wastewater Treatment Plants by

Hill and Barth (1977) developed a dynamic mathematical model for the

simulation of animal waste digestion which involved influent with more organic

matter and extremely high nitrogen content . The model developed attempted to

include the breakdown of waste and acid formation, production of gas and car-

bonate equilibria with the addition of nitrogen and cation balances . Finally the

mathematical model was verified with the data collected from the pilot scale

digesters. According to Hill and Barth (1977), the problem of animal waste

digestion is process instability because this waste can inhibit itself either by

high ammonia concentration or high organic acids .

Simulation and mathematical modeling help us to understand the process

mechanisms as well as save time and money . Moreover, knowledge from

simulation is useful for modifying the mathematical model and developing

laboratory experiments, but simulation primarily offers qualitative answers

rather than quantitative .

E. Optimization

Two main objectives of wastewater treatment plants are to maximize the

efficiency and minimize the cost . As these two objectives are conflicting,

research must be conducted by accessing a specified requirement that restricts

the size of the process units to maximum efficiency or minimize cost . The most

frequently observed objective is to minimize cost with a specified insured

efficiency .

In the past, engineers had the tendency to optimize the individual system

not the overall. The trend had been to design the most efficient unit processes,

each at least cost and then combine the units to form an optimum wastewater

34

Page 46: Optimal Design and Operation of Wastewater Treatment Plants by

treatment system . If only aeration tanks are optimized in an activated sludge

plant, it will be found that the least cost alternatives will be the one with the

lowest possible detention time with minimum possible solids concentration .

This will lead to an increased loading in the stabilization stage of the system,

resulting in an increased cost for that phase . So for an optimal overall system,

the individual units cannot be minimized separately, must be considered as a

part of the total system. There was neither an effort to maximize the efficiency

without considering cost, nor an attempt to arrive at a minimum cost without

considering the efficiency. The accuracy of the optimum solution depends upon

the accuracy of the mathematical model describing treatment plant operation,

cost functions, and accuracy of the optimizing algorithm .

Two principal trends in the optimization of wastewater treatment sys-

tems have been encountered in the literature (a) Simplified mathematical model

with elaborate and advanced optimization technique (b) Advanced and ela-

borate mathematical model with simplified optimization technique .

The literature on the performance of unit processes is voluminous, but

techniques to find the optimal performance is limited . Smith (1969) was the

first researcher to calculate the performance and cost of the system as a whole,

based on the relationship developed for the individual unit processes .

E-1. Simplified Mathematical Models :

Shih and Krishnan (1969) developed an optimum wastewater treatment

system using dynamic programming . Ecker and McNamara (1971) demon-

strated the use of geometric programming in the optimal design of wastewater

treatment systems by reworking the example problem solved by Shih and

35

Page 47: Optimal Design and Operation of Wastewater Treatment Plants by

Krishnan. According to Ecker and McNamara (1971) decision variables are

BOD5 removal efficiencies at each of unit process .

BOD

rljBOD5

(2.19)M,

where,

rh = efficiency of the unit j .

Optimum combinations and efficiencies of various unit processes were

identified but no wastewater component except BOD5 appeared in the model .

The cost associated with the unit process considered was

b .Ci = a . rh

where,

Cj = total annual cost,

a ,b = constants for process j .

The above equation implies that removal efficiencies are independent of

influent concentration and the position of the plant i.e ., each unit is capable of

removing any BOD5 load from zero to removal approaching 100% with the

constraint of non-negativity of the constant b

Shih and Defilippi (1970) demonstrated the application of dynamic pro-

gramming in optimal design of wastewater systems and considered BOD5

removal in primary sedimentation tank as a function of overflow rate and

influent BOD 5 and load for other units with certain restrictions .

(2.20)

Page 48: Optimal Design and Operation of Wastewater Treatment Plants by

Optimal design of wastewater treatment plants considered above, were

more concerned with the demonstration of a particular optimization technique

rather than working with a realistic model .

E-2. Advanced Mathematical Model

The models developed by Parkin and Dague (1972), Berthouex and Pol-

kowski (1970), Middleton and awrence (1976), Fan et al . (1974), and Tyteca

and Smeers (1981) are complex and complete with fewer process units but

optimization techniques used are much simpler than preceding cases . These

models are more oriented towards practicing design engineers with the type of

problem encountered in the field and solution methods that can easily be

adapted in practice .

Parkin and Dague (1972) applied an enumeration technique in the

optimal design of a wastewater treatment system and showed that the least

efficient primary sedimentation tank, in terms of suspended solids removal, i .e .

smallest primary sedimentation tank is desirable, high mixed liquor suspended

solids in the aeration tank is economical, and anaerobic digestion is less expen-

sive than aerobic digestion of excess sludge stabilization . This concludes that

the most efficient individual units combined together may not lead to the

optimal system. Enumeration technique is simple and easily be applied in prac-

tice by design engineers .

Middleton and awrence (1976) proposed an enumerative graphic tech-

nique for cost optimization of wastewater treatment using steady state

mathematical model, and showed that unit sizes and capacities are functions of

activated sludge solids retention time, mixed liquor volatile suspended solids,

37

Page 49: Optimal Design and Operation of Wastewater Treatment Plants by

recycle ratio, thickener underflow suspended solids concentration, suspended

solids removal efficiency of primary settling tank and digester solid retention

time. The minimum cost was determined graphically for constant and variable

solid retention time of each subsystem .

Berthouex and Polkowski (1970) used Hookes and Jeeves pattern search

technique, considering the parameter of uncertainty in the design of wastewater

treatment systems. Their study was more realistic and permitted relative relia-

bility of each unit process along with cost and treatment capabilities in obtain-

ing the optimal design .

where,

In all the above cases, the objective function appeared is given below,

n

n r 1Minimize TC = Y Ci (11 i) + I Y

r Cit Ol i )

r

=

discount rate,

t

=

number of periods in planned horizon,

rli

=

design variables,

Ci (rli )

=

capital cost,

Ci1 (rli )

=

operating cost,

i=1, . . .,n denotes the unit process.

The cost functions used are in the form,

n B €C = I Ai vi (rli ))

i=1

where,

i=1

i=1 t=1 (1+a)

38

(2.21)

(2.22)

Page 50: Optimal Design and Operation of Wastewater Treatment Plants by

C

=

capital or operating costs,

Al and Bl

=

estimate constants,

rli

=

process design parameters,

fj (Ill )

=

a simple function of r), generally rl or e' I .

Middleton and awrence (1976) also showed that the combination of indepen-

dently optimized process units will not lead to a global optimal system which

confirms Parkin and Dague (1972) and Narbaitz and Adams' (1980) conclusion .

Fan et al . (1974) used a modified simplex pattern search technique for the treat-

ment systems with objective function on capital costs only .

McBeath and Eliassen's (1966) sensitivity analysis showed that the vari-

ables which have more influence on the total cost are the global efficiency,

influent flow rate, and mixed liquor suspended solids concentration in the aera-

tor and influent BOD 5 load. They have also showed that the accuracy of cost

parameters have much greater influence on total cost than the performance vari-

ables. Middleton and awrence (1976) proposed the selection of an optimal

design 'region' rather than pinpoint to take into account the inaccuracy of

parameters and decision variables and to provide greater flexibility in applying

optimal values to the system design .

Tyteca and Smeers (1981) developed an advanced mathematical model

of steady state activated sludge wastewater treatment systems and optimized the

system using geometric programming . They considered capital and operation

and maintenance costs in their objective function and 0 & M costs were con-

sidered constant. They recommended that the discount factor should be

replaced by a continuous function for variable 0 & M costs .

39

Page 51: Optimal Design and Operation of Wastewater Treatment Plants by

ynn et al. (1962) used linear programming for optimal design of waste-

water treatment systems . The problem formulated is equivalent to the trans-

shipment problem and be solved by network algorithm . One advantage of this

technique is that it can handle problems which involve a system of non-serial

nature. The algorithm and computational procedure developed are elaborate

and cost and performance relationships are simplified, similar to Ecker and

McNamara (1971) .

All studies mentioned above have undertaken system optimization with

BOD 5 reduction only. With the introduction of performance constraints such

as suspended solids, COD and nutrient removal, the current procedure will be

very complex . Optimal solution of BOD 5 removal may not lead to optimality

by others. Network model (with splitting nodes) is capable of handling multi-

ple constraint parameters, such as BOD 5, suspended solids, COD and nutrient

removal which overcomes the difficulties encountered by mathematical pro-

gramming formulations in this direction . Thus cost minimization may be

achieved with respect to multiple water quality parameters . Adams and Pana-

giotakopoulos (1977) presented a network algorithm which was used to solve

the industrial wastewater treatment problem formulated by Shih and Krishnan

(1969) and the approach was suggested for use in solving the multiparameter

effluent quality optimization problem . They proposed that the network algo-

rithm is capable of handling both convex and non-linear cost transformation

function of the non-decreasing type .

40

Page 52: Optimal Design and Operation of Wastewater Treatment Plants by

III. MODE DEVEOPMENT

Modeling is the art of approximating a system for the purpose of learn-

ing its characteristics without interacting the system itself. Modeling by its

nature is revolutionary, provides a test ground for studying the effects of vari-

ous changes that it can have on real world systems . One of the objectives of

this research is to develop a dynamic mathematical model for the activated

sludge process describing process oxygen requirement, the solid production

rate, and oxygen demand of treated effluent during transient loading . Plants

which are designed for carbonaceous substrates removal may achieve

nitrification when sludge age is high . In such a case, the oxygen utilization will

be different since nitrification exerts a significant portion of oxygen demand

and for this reason the dynamics of nitrification is considered herein . The

dynamic model considered also includes anaerobic digestion . In order to use a

model for design and operation, it must be capable of predicting process oxygen

requirements, solid production rates, and oxygen demand of the treated effluent

during transient loadings. Influent suspended solids and refractory substances

are also incorporated in the model because these will change the design and

operational parameters .

A. Model Inputs

Wastewater flow rates and pollutant concentrations vary constantly.

They are influenced by diurnal, weekly, yearly seasonal, and random forces .

The mean values of the diurnally varying parameters are commonly used as an

input for steady state analysis, whereas time series analysis is used for dynamic

analysis, to determine periodic or deterministic components of the input . Box

and Jenkins (1970) have developed the time series analysis and Goel and

41

Page 53: Optimal Design and Operation of Wastewater Treatment Plants by

aGrega (1974), Berthouex and Co-workers (1975, 1978) used this technique to

predict wastewater flow rates and pollutant concentrations .

An alternative time series analysis, Fourier Transform Analysis, is used

in this investigation . The time series analysis by Box and Jenkins (1970) is

considered more powerful, but with the limited data available, the use of

Fourier Transform Analysis was more applicable .

Influent BOD 5, total suspended solids and volatile suspended solids data

are obtained from the City of Atlanta treatment plant . Figures 3 .1 and 3 .2 show

the original BOD5 data and Fourier Transform reconstruction using five com-

ponents. Harmonic spectrum diagram indicates the fluctuations and seventh

and fourteenth (Figure 3 .2) correspond to daily and twice daily fluctuations .

Another problem with input parameters is the relationship between vari-

ous oxygen demand measurements. The exact relationships between BOD YBODU , COD, and TOD are not possible because it depends on the composition

and levels of treatment of wastewater and others . The relationships used by

Busby (1973) are used for the purpose of this investigation . Relationships

between different pollutant concentrations used by Stenstrom (1975) with the

modification of soluble non-biodegradable substrate shown in Figure 3 .3 are

used in this investigation .

B. Primary Clarifier

The primary clarifier is the principal process used in wastewater treat-

ment plant to remove settleable solids from wastewater before entering the bio-

logical treatment process. This also results in a reduction in BOD and the

'masking effect', the phenomenon of reduction in activities of biological sludge

42

Page 54: Optimal Design and Operation of Wastewater Treatment Plants by

00 0

CD

Fig .

3.1 Actual and Reconstructed Biochemical Oxygen Demand, gm /m

3

15.0

30.0

45,0

60.0

75:0

90.0

10.0

120.

0

135.

0

150.

0

165.

0TIME (fouRS)

Page 55: Optimal Design and Operation of Wastewater Treatment Plants by

0

SN0ONr

000

aWo

r20110Mi,`

a00_n

a0N

oilt 111111 111 ;, .c'b.00

9 .00

18.00

27.00

6.00

IC45 .00NUMBER

.00

63 .110

72 .00

61 .00

90.00

Fig . 3.2 Magnitude Spectrum for Biochemical Oxygen Demand, gm /m3

44

Page 56: Optimal Design and Operation of Wastewater Treatment Plants by

1.0

1.0

0.21ss

NON-10ATIE

0.21

o.a0

0.20

PARTICATE

vssUS

210-I GRAI&E

0.790.79

0 .3yss

TOONDN"BIO GPA011BE

I N-BIOOEGRAOAa

0.237

0.85

0.70.0

1.50.356

0.63

1 .5

Fig. 3.3 Relationship Between Pollutant Concentrations

45

0.43

0.83

Page 57: Optimal Design and Operation of Wastewater Treatment Plants by

due to adsorption of suspended solids (Kuo et al . 1974) and a substantial damp-

ing of shock loads .

Design and modeling of primary clarifiers are difficult due to variable

influent suspended solids and flow rate . The design of a primary clarifier is also

affected by the distribution of settling velocities caused by the variation in size,

shape, and density of suspended particles in influent wastewater . Density and

temperature fluctuations are also important .

Hazen (1904) used the ideal basin concept and demonstrated that

clarification is a function of surface area and independent of basin depth . How-

ever, Hazen did not consider flocculation in his analysis . Flocculent particles

can coalesce increasing the terminal settling velocity. Bryant (1972) proposed a

dynamic mathematical model considering both mixing and clarification . The

mixing phenomena was approximated by considering five continuous flow

stirred tank reactors (CFSTR) in series . The use of five continuous flow stirred

tank reactors leads to a mixing regime which is neither plug flow nor complete

mixing. evenspiel (1967) has shown that this concept is useful for approxi-

mating a non-ideal mixing regime .

Hazen's ideal settling basin model has been gradually changed to tur-

bulent mixing models proposed by later investigators, including Dobbins

(1944), Camp (1946) 'and Shiba (1979) . Takamatsu et al . (1974) developed a

steady state parabolic partial differential equation to find the effect of resuspen-

sion on removal efficiency and to predict the optimal depth of sedimentation

basin. The scouring problem was treated as a boundary value problem of the

second order PDE with specific boundary condition including scouring parame-

ter. The same concept with the modification of non-steady state is used in this

46

Page 58: Optimal Design and Operation of Wastewater Treatment Plants by

research .

The two dimensional non-steady state dispersion model for the rectangu-

lar basin is represented by

ac

ac

ac

a2c

a2c=E

+Eat

ax

n az

X ax e

Z az 2

(3.1)

The boundary conditions are :

C =Co at x =0

ac=Oat x =

ax

acE

+kwz a

w C=O ; atz=0z

ac

EZ az+wP C=0 ; atz=H

where,

x

=

flow direction ()

z

=

upward direction ()

C o

=

concentration of suspended solidsat the inlet (MI ),

C

=

concentration of suspended solids (MI 3),

u

=

longitudinal mean velocity of the flow (JT),

w

=

settling velocity of suspended solids (/T),

E

=

longitudinal dispersion coefficient (2/T ),

EZ

=

vertical dispersion coefficient ( 2/T),

k

=

scouring parameter .

47

(3 .2)

(3 .5)

Page 59: Optimal Design and Operation of Wastewater Treatment Plants by

u, w , , E , EZ and k considered constant throughout the basin . The physical

interpretation of the scouring parameter are given by Goda (1956) as follows : k

> 1, tendency of scouring ; k=1 balance of deposition and scouring ; 0 < k < 1,

tendency to deposit; and k=0, deposition only . In a case of normal operation

the rate of deposition exceeds the rate of scouring . Therefore, the value of k is

usually between zero and one. Equation (3 .4) indicates that some of the sedi-

ments at the bottom will come back again to the main body of the flow . Equa-

tion (3 .5) means that there is no transport of particles across the free surface .

Scouring parameter is an important index for the design and operation of

settling basins . It depends on both the characteristics of basin hydraulic proper-

ties (e.g. flow rate, mixing intensity, and flow pattern) and settling properties of

sediments (e.g . density, shape, and particle diameter distribution) .

The dispersion coefficient (E) can be measured experimentally using

tracer studies . Takamatsu et al . (1974) formulated an equation which describes

his experimental results, which are used here for estimating E . The mathemat-

ical equation formulated is given by

The purpose of biological treatment of wastewater is to coagulate and

remove non-settleable colloidal solids and to stabilize organic matter in the

presence of microbial mass under a controlled environment . The first model for

48

Ex = 3 .59 exp (58 .5*F )

where,

F = Froude number = u lN'g--H

(3 .6)

C. Biological Reactor Model

(3 .7)

Page 60: Optimal Design and Operation of Wastewater Treatment Plants by

continuous growth system was developed by Monod (1942) using pure culture

and a single soluble substrate. Monod (1942) proposed that the growth rate is a

function of limiting substrate concentration as shown in equation (3 .8)

•S•

KS + S

(3.8)

where,*

=

maximum specific growth rate (T-1),

S

=

limiting substrate concentration (MI 3),

K = saturation concentration (MI 3).

Many other formulations exist for growth rate coefficient, but Monod's model

is widely used .

Net organism production considering Monod's model can be written as

follows :

where,

X =(• - Kd )*X

X = net organism production (MI 3),

Kd = decay coefficient (T -1) .

(3.9)

The applicability of equation (3 .8) to wastewater treatment can be criticized

because it is developed for a single soluble and homogeneous substrate . Siddiqi

et al. (1966) proposed that domestic wastewater contains 60% to 70% particu-

late matter. Equation (3.9) does not consider the lag phase and it is non-specific

with respect to microbial mass . Actually growth rate should be proportional to

active mass, not the entire MVSS . Moreover, the Monod model cannot be

49

Page 61: Optimal Design and Operation of Wastewater Treatment Plants by

used for time varying organic loading and influent flow rate .

Structured models were developed to correct the limitations of Monod

and other distributed models . The structured model developed by Tench (1968)

for the treatment of domestic wastewater considered sludge mass into three

components: an adsorbed oxidizable fraction, active portion and biologically

inert portion . Westberg (1967) considered biological solids into living and dead

cells and also accounted for non-biodegradable suspended matter in the influent

wastewater. The structured model schematic used in this investigation is shown

in Figure 3 .4 .

The particulate and complex organic matters are adsorbed on activated

sludge floc and the energy is stored . Porges et al. (1956) concluded from their

experiments that substrates can be stored on organisms and the rate of storage

can exceed the rate of stored substrate utilization by up to 2.6 times. Direct evi-

dence of adsorption and storage phenomenon can be found in the case of con-

tact stabilization.

The removal and transport of soluble substrate to stored substrate

developed by Blackwell (1971) was modified by Ekama and Marais (1979) to

account for the direct metabolism of soluble substrate by active organism . The

net rate of removal of biodegradable substrate is expressed as :

where,

rSD = KT*XA*SD* (f. - fs ) - RSD*XA*SD

rSD

=

removal rate of biodegradable solublesubstrate, (MI T),

SD

=

biodegradable soluble substrate

50

(3.10)

Page 62: Optimal Design and Operation of Wastewater Treatment Plants by

SOUBE

SUBSTRATE

(sn)

PARTICUATE

SUBSTRATE

(SP)

DIRECT SYNTHESIS

(RSD)

RH

STORED

PARTICUATE

SUBSTRATE

(xP)

Fig. 3.4 Schematic Structured Model

51

RXA

I

ACTIVE

MASS

(xA)

IINERT

MASS

(XI)

Page 63: Optimal Design and Operation of Wastewater Treatment Plants by

where,

concentration, (MI 3),

KT

=

transport rate coefficient ( 3/M T )II

fs

fs

RSD

XA

XS

maximum fraction of stored mass,

fraction of stored mass, XS/(XS+XA),

direct growth rate coefficient ( 3/M T).

active mass concentration (MI 3)

stored mass concentration (MI 3) .

The removal of particulate matter from the liquid phase by the activated

sludge is much faster than removal of soluble substrates. A transport expres-

sion of particulate matter is not required because it is removed immediately

upon contact with flocs. The biodegradable stored particulate fraction under-

goes hydrolysis and transforms to stored mass .

Clift (1980) proposed the rate of stored particulate hydrolysis in terms of

Monod type saturation function which is represented by the equation below :

rxP = RH* (fp /(Ks , + .fp ))*XA*Y3

rXP

=

rate of stored particulate substratehydrolysis (MI T),

RH

=

hydrolysis rate coefficient (T -1),

fp

=

fraction of stored particulate substrate,(XP/(XP+XA))

Kp

=

saturation coefficient,

Y3

=

conversion factor, gm of XS orSD/gm of XA,

XP

=

stored particulate substrate (MI 3) .

52

(3 .11)

Page 64: Optimal Design and Operation of Wastewater Treatment Plants by

Active mass is synthesized from stored mass as well as extracellular

soluble substrate. The equation proposed by Clift (1980) for the production of

active mass from stored mass and direct metabolism of extracellular soluble

substrate is expressed as :

where,

rXA

=

the net rate of production from stored mass andsoluble substrate (MI T),

RXA

=

storage growth rate coefficient, (T -1),

Y1

= mass of XA produced per unit mass of XS orSD utilized .

rxA = RXA*XA*fs + Y 1*RSD*XA*SD

A residual non-biodegradable particulate fraction is formed during the

decay of active organisms. The production of inert mass is expressed as fol-

lows:

r = Y2*KD *XA

rate of production of inert mass (MI 3T),

€ mass of XI produced per unit mass of XA,

decay rate coefficient (T-1 ) .

Stored mass is obtained from soluble substrate and hydrolysis of stored

particulates. It is assumed that no oxygen is required for the hydrolysis of

stored particulate substrate and transport of soluble substrate to stored mass .

53

(3.12)

(3 .13)

Page 65: Optimal Design and Operation of Wastewater Treatment Plants by

rXS = KT*XA*SD* (fs -fs ) + RH*XA* (fp /(Kp +fp ))

rXS =stored mass production rate (M I 3T ) .

The non-biodegradable soluble organics and non-volatile solids are

included in the model because non-biodegradable soluble organics exert an

oxygen demand when measured by COD or TOD . Non-volatile solids strongly

influence on sludge production.

C-1. Nitrification

The use of Monod growth rate function in wastewater treatment systems

has been criticized previously mainly for it's incapability in predicting the time

lag in the growth phase . However, many researchers (Hofman and ees, 1953 ;

ees and Simpson, 1957) have demonstrated that Monod kinetics can be used

in case of nitrification because there is no significant time lag due to change in

substrate concentration on the growth rate response to the nitrifying bacteria .

Nitrification is a process in which oxidation of ammonium to nitrite and

nitrite to nitrate is carried out by autotrophic bacteria, Nitrosomonas andNitrobacter. The growth rate of Nitrosomonas can be expressed as follows :

where,

rXNS

•NS

KDNS

rXNS = (•NS -KDNS)*XNS

€ net growth rate of Nitrosomonas (MI 3T),

€ specific growth rate of Nitrosomonas (T -1),

Nitrosomonas decay coefficient (T-1) .

(3 .14)

The rate of removal of ammonium nitrogen by Nitrosomonas can be expressed

54

Page 66: Optimal Design and Operation of Wastewater Treatment Plants by

as:

where,

rNH4

YNS

XNSrNH + = - €NS *

4

YNS

Ammonium ni rogen is also consumed by he ero rophic bac eria. Ammonia is

released o he solu ion as a resul of breakdown of ni rogeneous ma er and

au olysis of cells, and i is removed from he solu ion as a resul of he syn hesis

of new cells. In he case of domes ic was ewa er wi hou ni rifica ion, he con-

cen ra ion of ammonium ni rogen in he effluen is close o ha in he influen

was ewa er, bu he concen ra ion of he organic residual ni rogen in he effluen

is much less han in he influen was ewa er. This difference sa isfies he ne

ni rogen requiremen during syn hesis of new cells. I is assumed ha

ammonium ni rogen is produced during organism decay as a resul of lysis .

The ra e of ammonium ni rogen removal by he ero rophs is considered propor-

ional o he ne ra e of ac ive mass forma ion as follows :

rHNH + = -(YNS *XA* (RXA*fs + Y 1 *RSD *SD) - YND *KD *XA )4

(3 .17)

where,

rHNH4

YNS

YND

-

rate of removal of ammonium nitrogendue to nitrification (MI 3T ),

yield coefficient, mass of Nitrosomonasformed r unit mass of ammonium nitrogenoxidized.

net rate of ammonium nitrogen removalby heterotrophic organism (M-NH4 -NI 3T ),

mass of ammonium nitrogen utilized per unitactive mass produced during synthesis,

mass of ammonium nitrogen produced per unitactive mass destroyed .

55

(3.16)

Page 67: Optimal Design and Operation of Wastewater Treatment Plants by

Hoover and Porges (1952) have shown ha he composi ion of ac iva ed sludge

approxima ely correspond o he empirical formula C 5H7N02. Thus for each

gram increase in sludge mass 0.124 grams of ammonium ni rogen is required .

The overall ra e of ammonium ni rogen removal is he sum of he equa ion

(3 .16) and (3 .17) .

The grow h ra e expression of Ni robac er is similar o Ni rosomonas.

where,

where,

rNO _ =2

ni ri e ni rogen produc ion ra e (M NO 2_N/3T),

YNB

=

yield coefficien , mass of Ni robac er formedper uni mass of ni ri e ni rogen oxidized.

The ra e of produc ion of ni ra e ni rogen by Ni robac er is represen ed as fol-

lows:

rXNB

PNB

KDNB

rXNB = (PNB - KDNB )*XNB

rNO2

The expression for ni ri e ni rogen con ains wo erms for grow h ra e , a posi-

ive erm for conversion of ammonium ni rogen o ni ri e by Ni rosomonas and

a nega ive erm for he oxida ion of ni ri e o ni ra e by Ni robac er.

€NS *XNS €NB *XNB

YNS

ne grow h ra e of Ni robac er (MI 3T ),

specific grow h ra e of Ni robac er (T-1),

Ni robac er decay coefficien (T-1)

YNB

(3 .19)

56

(3.18)

Page 68: Optimal Design and Operation of Wastewater Treatment Plants by

€NB *XNB

rNO ' = YNB

where,

rNQ _ = ni ra e ni rogen produc ion ra e, (M ND 3 -NI 3T ) .3

For a more de ailed analysis Poduska's (1973) work should be consul ed.

C.2. Oxygen U iliza ion

Dissolved oxygen in ac iva ed sludge is u ilized in wo ways (a) u iliza-

ion of oxygen by he ero rophic bac eria for he des ruc ion of carbonaceous

ma er, and (b) u iliza ion of oxygen by au o rophic bac eria for he syn hesis of

ac ive mass from s ored mass and ex racellular subs ra es and decay of organ-

isms. There is an oxygen requiremen for he hydrolysis of paricula e subs ra e

bu i is considered negligible for his research .

The oxygen u iliza ion by he ero rophic bac eria is represen ed as fol-

lows:

1-Y 1rOH = (

)*XA*Y1

(RXA*fs+Y1*RSD*SD) + (1-Y2)*KD *XA(3.21)

where,

rOH = ne oxygen up ake ra e by he ero rophic bac eria, (MI 3T ) .

The erm (1-Y 1) represen s he oxygen equivalen used for respira ion . The

firs erm in equa ion (3.21) represen s he oxygen requiremen s for syn hesis ofs ored mass and ex racellular subs ra e and he las erm is for endogeneousrespira ion .

5 7

(3 .20)

Page 69: Optimal Design and Operation of Wastewater Treatment Plants by

The concen ra ion of ammonium, ni ri e and ni ra e ni rogen is expressed

as elemen al ni rogen . The heore ical oxygen demand for conversion of

ammonium o ni ri e and ni ri e o ni ra e can be calcula ed from he oxida ion

equa ions .

(3 .22)

2NO 2 +0 2-4 2NO 3(3 .23)

3.42 grams of ni rogen is required for he oxida ion of 1 gram of ammonium

ni rogen o ni ri e ni rogen. An addi ional 1 .142 grams of oxygen is required

for he oxida ion of 1 gram of ni ri e o ni ra e. The amoun of ni rogen used

for syn hesis is considered negligible compared o he amoun oxidized o

ob ain energy .

The ra e of ni rogeneous oxygen demand by ni rifiers can be expressed

as follows :

where,

roN = oxygen up ake ra e by ni rifiers (MI 3T).

The ransfer of oxygen from gas phase o liquid phase is propor ional o he

sa ura ion concen ra ion of dissolved oxygen and he ac ual concen ra ion .

Therefore,

where,

rDO

2NH4 + 30 2 -4 2NO2 + 2H20 + 4H+

€NS *XNS

€NB*XNBrON = 3.42

+1.142YNS

YNB

(3 .24)

rD0 = KA (DOS-DO)

oxygen ransfer ra e (MI 3 T),

58

(3.25)

Page 70: Optimal Design and Operation of Wastewater Treatment Plants by

KA

=

oxygen mass ransfer coefficien (T1),

DOS

=

sa ura ion dissolved oxygen concen ra ion = KH*P

KH

=

Henry's law cons an , M/ a m.,P

=

par ial pressure of oxygen a gas phase, a m.

The ne dissolved oxygen consump ion is represen ed as follows:

1-Y 1*XA* (RXA*fS + Y 1*RSD*SD )

€NS *XNS

€NB *XNB- (1-Y2)*KD *XA - 3.42

-1.142YNS

YNB

+ KA (DOS -DO)

(3.26)The summary of he ma hema ical model and he informa ion flow is shown in

Figure 3.5 .

D. Secondary Clarifier Model

The dynamic analysis of ac iva ed sludge will be incomple e wi hou he

se ler dynamics . The process performance of ac iva ed sludge is direc ly

dependen on he secondary clarifier because he recycle organisms concen ra-

ion is primarily a func ion of hickening capabili ies of he clarifiers . S eady

s a e models were considered useful for he design and he process evalua ion in

he pas bu hey are inadequa e for process con rol because hey fail o predic

he ime dependen responses o he ransien inpu s.

Many researchers (Bryan , 1972 ; Busby, 1973 ; Tracy, 1973) have pro-

posed dynamic ma hema ical models for he solid liquid separa or. All hese

models used some cons rain s o predic he resul consis en wi h he solids flux

59

Page 71: Optimal Design and Operation of Wastewater Treatment Plants by

Y1

-0- Y2)'KD •XAj-3.42 €NS-1 .142 €NB

+ KAj (DOS - DOj )

Fig . 3.5 Summary of Ma hema ical Model and Informaion Flow Diagram

60

KTRH

RS

fs~

fsRXA

KD

Y1Y2

€NS

€NBKDNS

YNSYNBKDNB

ViKAjDOS

S0, SR Si - KT - XAj - Si (fs% fs.) - RS •XAj 'S S3SNO , SNR SNj

j

SN3XPO , XPR XPj

XSO, XSR xSj -RH-XAj(-ff/K :j-+XP3

XAO, XAR XAj - KT •X Aj • Sj (fs- fs1,)-RH'XAj -RXA •XAj - fs

1./Y 1 XS3

~

XIO, XIR X1 i - RXA - XAj • fs . - Y1 • RS • XAj • Si - KD - XAj1 XP3~~

XNO, XNR XNj -1 .AI - E.A,- Y2 KD XAj XA3

X13NH40, NH43 NH4j0.

- €NS ' XNS / YNS NH43N020, 23 NO2j( €NS ' XNSj / YNS) - (€NB ' XNBj / YNB) 0.

NO23NO30, N033 N03j

lNB •XNBj/YNBN033

XNSO, XNSR XNSj

XNBjXNSj ( €NS - KDNS) XNS3

XNBO, XNBR

DOjXNBj (€NB - KDNB ) XNB3

DO0 , DOR-(I.-Y1) XAj (RXA •XAj + Y1 - RSD- Sj) DO301, OR

0

Page 72: Optimal Design and Operation of Wastewater Treatment Plants by

heory (Dick, 1970) . The cons rain s were imposed upon he model o keep he

concen ra ion a all poin s above he compression zone less han he limi ing

concen ra ion. S ens rom's (1975) approach is used here which is essen ially

same as Bryan 's (1972), excep ha he flux limi a ion used be ween layers in

he separa or, ra her han a cons an based upon he s eady s a e flux curve .

The non-s eady s a e one dimensional con inui y equa ion for a separa or

is formula ed using a ma erial balance which is represen ed as :

ac a ac PV C )=- (D

)

-Reac iona

az

az

az

(3.27)

where,

z

C

DVSz

Assump ions are (a) zero dispersion (plug flow, D=0), (b) no biological

reac ion in he reac or, and (c) uniform solids concen ra ion in he horizon al

plane, he con inui y equa ion becomes :

ac

ac

aVS

a =-(VS

+ v) az - c az

(3.28)

where,

C

=

slurry concen ra ion (MI 3),

VS

=

se ling veloci y of slurry concen ra ionrela ive o fluid (Ur),

U

=

downward fluid veloci y (IT),

concen ra ion (MI 3),ime (T),

dispersion coefficien ( 2/T),•

veloci y (IJT),•

dis ance ().

verical dis ance in he solid liquid separa or (),•

ime (T).

61

Page 73: Optimal Design and Operation of Wastewater Treatment Plants by

The se ling veloci y is de ermined by measuring he ini ial subsidence of

a slurry in a large cylinder. By using differen concen ra ions, a se of da a

which defines he se ling veloci y func ion is ob ained. The ba ch flux is

ob ained by mul iplying se ling veloci y by concen ra ion as shown in Figure

3.6 . The bulk flux is ob ained by mul iplying underflow concen ra ion wi h

solids concen ra ion and he addi ion of bulk flux and ba ch flux resul s in o al

flux shown in Figure 3 .6 .

The concen ra ion a he minimum of he o al flux curve is known as

limi ing concen ra ion which is useful for he de ermina ion of loading condi-

ion of he solid liquid separa or. The solids concen ra ion in he sludge blanke

may be predic ed for cri ical loading, unloading and overloading condi ions

using flux heory as shown in Figure 3 .7. A se ler becomes overloaded when

he limi ing layer rises up and reaches he feed poin .

Tanks in he series me hod is used for he solu ion of he ranspor equa-

ion in which number of differen ial elemen s is a func ion of dispersion

coefficien . The modified con inui y equa ion is solved by CSMP 3 .

The ma erial balance around he i h differen ial elemen produces he fol-

lowing equa ion:

ac U(Ci-1-C1) Min (GS1_ 1,GSi ) - Min (GSi ,GSi+1)

a

Oz

Oz

(3.29)

Equa ion (3.29) is modified o include boundary condi ions for he op and he

bo om elemen . The equa ion for he op elemen becomes;

62

Page 74: Optimal Design and Operation of Wastewater Treatment Plants by

J

5

12.0

8 .0 .

0 .0

T

40.0

Fig. 3.6 Flux Curves .

CRITICA

OADING

80 .0

120.0CONCENTRATION (GM/M3)

T - U C EROAD I NG

1

CONCENTRATION (GWM3)

Fig . 3.7 Solids Concenra ion Profiles

63

1 : TOTA

2 :BATCH

3 : BUK

160 .0 200 .0

-- V

OVEROADING

Page 75: Optimal Design and Operation of Wastewater Treatment Plants by

where,

aC 1 FUXIN - U.C 1 - Min (GSj ,GSj+1)

a

AZ

(3.30)

FUXIN

=

ne flux in o he se ler (M / 3T ),_ (Q 3*MSS - (Q 3-QR 1)*XEFF)/A,

Q 3

=

flow ra e o3 he clarifier (includingrecycle),( IT),

QR 1

= flow ra e of re urn sludgy (including flowra e of was e sludge),( IT),

MSS

mixed liquor suspended solids concen ra ion, (MI 3),

XEFF

=

effluen suspended solids concen ra ion, (M/ 3),

A

=

area of he solid liquid separa or ( 2) .

Zero se ling flux a he bo om of he clarifier simplifies he equa ion (3 .29) o:

aCn U. (Cn_1- Cn ) + GSn

a

Az

(3.31)

where,

n = subscrip of he bo om elemen .

The effluen suspended solids concen ra ion is calcula ed using second

order regression model of Cashion (1981) . The second order model is

represen ed as follows:

XEFF =B o+B 1 *SRT+B 2*HRT+B 3*ORA+B 11*SRT2

+B 22* HRT2+B 33*ORA 2+B 12*SRT*HRT

+B13* SRT*ORA+B 23*HRT*ORA

where,

64

(3 .32)

Page 76: Optimal Design and Operation of Wastewater Treatment Plants by

B

=

s a is ical parame ers,VA*MSS+VC*MSSM

SRT

=

(Q

(3.33)1-QR o)*XEFF +QR o*MSSR

VA

=

volume of he aera ion basin, 3,

MSS

=

mixed liquor suspended solids concen ra ion, MI 3,

VC

=

volume of he clarifier, 3,

MSSM

=

mean solids concen ra ion in he clarifier, MI 3,

Q 1

=

influen flow ra e, 3/T,

QR o

=

was e flow ra e, 3/T,

XEFF

=

effluen suspended solids concen ra ion, M / 3,

MSSR

=

underflow solids concen ra ion, MI 3,

HRT

=

hydraulic re en ion ime, T,•

IA/Q 1,

ORA

= clarifier overflow ra e, 3/2T,•

QR/A

QR

=

clarifier effluen flow ra e, 3/T,

A

surface area of he clarifier, 2/T .

The above equa ion for he effluen suspended solids concen ra ion is valid onlyin he case of a s eady s a e condi ion. This equa ion is used here only becausehere does no exi any rela ionship which predic s effluen concen ra ion moreaccura ely han Cashion's (1981) . The overall sys em informa ion flow, exclud-ing anaerobic diges ion is shown in Figure 3 .8 .

E. Anaerobic Diges ion

Anaerobic diges ion is a biological process used in was e rea men forhe con rolled des ruc ion of biodegradable organic ma er. This process iscurren ly applied a mos major municipal was e rea men plan s. Despi e he

6 5

Page 77: Optimal Design and Operation of Wastewater Treatment Plants by

r

r

Qi'

TSS

I

NE41

DODNH4

PRIMARY SEDIMENTATION BASIN

+i -~ B a+B EP

p s 812

s bZ2

C-C0 a 1-0

If .0 a I-

Bi 8Z + k* psC - 0 a Z - 0

B.P+k'WC .'0 a Z-H

Q1 SO SNO AO ZPO ISO INOV

110

AERATION BASIN

DO 3

XP3Q3

D43 f

83

113

SN3

NB43-

IA3

NO23.

SOID IQUID SEPARATOR

143

N033

ISRXPR

IIRINR

V

S

QI

PAR AM

PAR AN

83

66

SN

Fig. 3.8 Sys em Informa ion Flow Diagram

Page 78: Optimal Design and Operation of Wastewater Treatment Plants by

widespread applica ion of anaerobic diges ion, he developmen of process con-

rol parame ers are empirical due o he complexi ies of he sys em. One of he

objec ives of diges ion research is he unders anding of he complex ecosys em

and developmen of more scien ific and reliable means of process design and

con rol .

Early researchers concluded ha anaerobic diges ion is a process in

which solid organic ma er is hydrolyzed by ex ernal enzymes o form shor

chain fa y acids. The shor chain fa y acids are consequen ly convered o

me hane and carbon dioxide as shown in Figure 3 .9.

Jeris and McCary (1976) observed ha bo h ace ic acid conversion and

carbon dioxide reduc ion were involved in me hane forma ion. They proposed

ha abou 75% of he me hane formed was from ace ic acid conversion .

Recen research s rongly sugges s ha he only organic acids which

me hanogens me abolize are ace a e and forma e, and emphasize he cen ral

posi ion of hydrogen produc ion and u iliza ion in ace a e and forma e fermen-

a ion (Bryan (1976), and Mah e al. (1977)). The new model shows he pro-

cess for carbohydra e me abolism which is mos consis en wi h he curren

informa ion on anaerobic diges ion (Figure 3 .10). In he old concep , as before,

fermen a ive bac eria hydrolyze organic ma er and form organic acids, hydro-

gen, and carbon dioxide . Hydrogen producing ace ogenic bac eria ob ain

energy for grow h by producing ace a e, hydrogen, and some imes carbon diox-

ide from organic acids produced by fermen a ive bac eria. Me hanogens u ilize

ace a e, carbon dioxide, and hydrogen and produce me hane and carbon dioxide

as final produc s (Bryan , 1979). The new concep wi h he considera ion of

differen acids (ace ic, propionic, and n-bu yric) are chosen for he

67

Page 79: Optimal Design and Operation of Wastewater Treatment Plants by

OTHER PRODUCTS

INSOUBE ORGANICS

SOUBE ORGANICS

VC)AT I E

ORGANIC ACIDS

EXTRACEUAR

ENZYMES

ACID PRODUCING

BACTERIA

AND BACTERIA CES

Fig. 3 .9 Anaerobic Diges ion of Organic Was es (Old Concep )

68

BACTERIA

Page 80: Optimal Design and Operation of Wastewater Treatment Plants by

YPACS

ACETIC

AC ID(HAC)

YANB

BIODEGRADABE

SOIDS

SOUBE

SUBSTRATE

YPACS

PROP IONIC

ACID

(PAC)

YXSO

YXS

YXPAC

N-BUTYRIC

AC ID(NBAC)

YNBACS Y

HYDROGEN

YXNBAC

YHNB

69

YHP

Fig. 3 .10 Anaerobic Digesion of Organic Was es (New Concep )

YXH2 CHq

Page 81: Optimal Design and Operation of Wastewater Treatment Plants by

ma hema ical model because ;

a.

ace ic acid has been shown o be precursor of approxima ely 70%

of he me hane formed in he rea men of domes ic was e,

b .

propionic and n-bu yric acid oge her are he precursor of 80% of

o al ace ic acid formed,

c.

propiona e +3H2O

- ace a e +3H2 + HCO 3 + H

d.

bu yra e

--, 2 ace a e + 2H2

McCary (1971) showed ha pro ein and carbohydra e fermen ing bac-eria grow rapidly, fermen ing subs ra es a a re en ion ime of less han oneday. However, fa y acids fermen ing bac eria grow more slowly and ac ivefermen a ion is possible only for re en ion imes grea er han 5 days .

Mos curren s eady s a e models of anaerobic diges ion process are

based upon Monod's (1942) sa ura ion kine ics. awrence (1971) used a

s eady s a e ma hema ical model for he design of he anaerobic diges ion .Graef (1972) proposed a dynamic ma hema ical model for various con rol s ra-egies ha can be applied o preven diges er failure . The dynamic ma hema i-

cal model developed by Hill and Bar h (1977) on animal was e diges ion was oin erface he fundamen al charac eris ics of he process and o unders and heoverall opera ion. Andrews (1969) proposed ha un-ionized vola ile acids aregrow h limi ing and inhibi ory o me hane bac eria . He presen ed experimen alevidence and evidence from microbiological li era ure o suppor hishypo hesis and compu er simula ions showed ha inhibi ion by unionized vola-ile acids predic s resul s similar o hose observed in he field. Graef (1972)

70

Page 82: Optimal Design and Operation of Wastewater Treatment Plants by

and Hill and Bar h (1977) considered he old concep in heir ma hema ical

model of anaerobic diges ion.

One of he objec ives of his research is o develop a dynamic ma hema -

ical model of anaerobic diges ion of domes ic was ewa er using he new con-

cep .

E-1. Ma hema ical Developmen

The dynamic ma hema ical model of anaerobic diges ion is developed by

ma erial balance equa ions of differen variables and species . S aring poin forma erial balance on anaerobic diges ion is biodegradable solids and he concen-ra ion a any ime can be ob ained by in egra ing he ma erial balance equa ion .

(dBD /d )=(QII /VD )* (BDO - BD )-(€BD *XBD /Yxso *CF) (3.34)

where,

BDO =C11 * ((MSSR 1+CONBD*PCC)IMSSR 2)

MSSR 1 = XAR +XPR +XSR +XNBR +XNSR

MSSR 2=MSSR 1+XIR +PCC +XNR

C11

=

se lejble solids concen ra ion,MI ,

Qu

= influen flow ra e, /T3 ,

VD

=

volume of he diges er, 3 ,

PCC

= concen ra ion of sludge from primary clarifier, MI 3,

CONBD = biodegradabili y of he sludge from he primaryclarifier,

XAR

=

ac ive mass concen ra ion of recycle sludge, MI 3,

71

(3.35)

(3.36)

(3 .37)

Page 83: Optimal Design and Operation of Wastewater Treatment Plants by

XSR

=

s ored mass concen ra ion of recycle sludge, MI 3,

XPR

=

paricula e mass concen ra ion of recycle sludge, MI 3 ,

XNBR

=

concen ra ion of Ni rfbac er ofrecycle sludge, M I ,

XNSR

= concen ra ion of Ni rrsomonas ofrecycle sludge, MI ,

XNVR

=

non-vola ile solids concen ra ionof recycle sludge, M I ,

XIR

=

iner mass concen ra ion of recyclesludge, M / ,

XNR

=

non-biodegradable solids concen ra ionsof recycle sludge, M I ,

€BD

=

specific grow h of he biodegradablesolids hydrolyzers, T ,

XBD

=

concen ra ion of he biodegradablesolids hydrolyzers, MI ,

yxso

=

soluble organic yield coefficien ,mg of organism/mg of soluble subs ra e,

CF

=

conversion fac or, 1 mg soluble subs ra eper mg of biodegradable solids .

The reac ion erm in equa ion (3 .34) represen s he conversion of insoluble

biodegradable solids o soluble organics .

The ma erial balance of non-biodegradable solids is represen ed by:

(dNNB Id ) = (QII /VD)* (NNBO - NNB )(3 .38)

where,

NNBO = influen non-biodegradable solidsconcen ra ion, MI ,

= C 11*((XIR+CONNBD*PCC)/MSSR2)

(3.39)

CONNBD = non-biodegradabili y of he sludge fromhe primary cla ifier .

7 2

Page 84: Optimal Design and Operation of Wastewater Treatment Plants by

The ma erial balance of soluble organics is given by :

(dS /d ) = (QII /VD)* (SO - S)-(€*XS /Yxs )

+ (€BD *XBD /Yxso *CF)* (1 .-Yxso -YC021 )

where,

SO

=

influen concen ra ion of solubleorganics, M / ,

Yxs

=

yield coefficien for acid formers, mgof organisms/mg of soluble subs ra e,

=

soluble subs ra e specific grow h ra e, T-1,

XS

=

microbial conce3n ra ion of soluble subs ra eoxidizers, M / ,

XP

=

microbial concen ra ion of propionicacid oxidizers, M / ,

XB

=

microbial concen raion of n-bu yricacid oxidizers, M / ,

YCO21

=

yield coefficien ofCO 2 from biodegradablesolids, gm of C0 2/gm of organism.

Second and las erms in equa ion (3.40) represen he u iliza ion

organics by acid formers in heir me abolism and produc ion of soluble organics

from biodegradable solids respec ively .

The ma erial balances on propionic, n-bu yric,ace ic acid and hydrogen

can be wri en as :

(dPT ld ) = (QII/VD)* (PTIN - PT)-(€P *XPT/YYPAC )

+ (€*XS/Yxs)* (1 .-Yxs-YCO22)*YPACS

(3 .40)

of soluble

73

(3 .41)

Page 85: Optimal Design and Operation of Wastewater Treatment Plants by

where,

(dNBT ld ) = (QII /VD )* (NBTIN NBT)-(€B *XBTIYXNBAC )

+ (€*XS /YXS ) * (1 •-Yxs-YCO 22)*YNBACS

(dHT /d ) = (QII /VD )* (HTIN HT)-(€M *XM /YXA )

(€P *XPTIYXPAC )* (l . YXPAC )*YAP

(€B *XBT/YXNBAC ) * ( 1 .-YXNBAC)*YANG

(p.*XSIYXS)* (1 •-YXS-YCO22)*YHCS

(dH2/d ) = (QII /VD )* (H2IN H2)-(€H*XH2/YXH2)

(gp *XPT/YXPAC )* (1 •-YXNPAC )*YHP

(€B*XBT/YXNBAC)* (1 •-YXNBAC )*YHNB

(€*XS/YXS)* (1 .-YXS-YCO22)*Y H, + (dH2/d )(3.44)

PTIN

=

influen concen ra ion of propionic acid, MI 3 ,

NTIN

=

influen concen ra ion of n-bu yric acid, MI 3 ,

HTIN

=

influen concen ra ion of ace ic acid, MI 3,

H21N

=

influen concen ra ion of hydrogen, MI 3,

YPACS

=

yield coefficien of propionic acid, moles ofpropionic acid/ moles of soluble subs ra e,

YNBACS

=

yield coefficien of n-bu yric acid, moles ofn-bu yric acid/ moles of soluble subs ra e,

YHACS

=

yield coefficien of ace ic acid, moles oface ic acid/ moles of soluble subs ra e,

YHzs

=

yield coefficien of hydrogen, moles of

74

(3.42)

(3 .43)

Page 86: Optimal Design and Operation of Wastewater Treatment Plants by

hydrogen/moles of soluble subs ra e,

YXPAC

=

yield coefficien , moles of organism/moles of propionic acid,

YXNBAC

=

yield coefficien ,moles of organism/molesof n-bu yric acid,

YXA

=

yield coefficien of me hane, moles oforganism/ moles of ace ic acid,

YXH2

=

yield coefficien , moles of organism/moles of hydrogen,

YAP

=

yield of ace ic acid from propionic acid,moles of ace ic acid/moles of propionic acid,

YANB

=

yield of ace ic acid from n-bu yric acid,moles of ace ic acid/moles of n-bu yric acid,

YHP

=

yield of hydrogen from propionic acid, molesof hydrogen/ moles of propionic acid,

YHNB

=

yield of hydrogen from n-bu yric acid, molesof hydrogen/ moles of n-bu yric acid,

YC0

=

yield coefficien of CO . form soluble2

subs ra e, gm of CO 2/ gm of organism,

(dH 2/d )

=

ne ra e. of hydrogen ransfer be ween gasand liquid phase.

Second erms in equa ions (3 .41) and (3 .42) represen he conversion of

ha acid o ace ic acid and second erms in equa ions (3 .43) and (3 .44)

represen conversion of ace ic acid and hydrogen o me hane gas. The hird and

forh erms in equa ions (3 .43) and (3 .44) are he conversion of propionic and

n-bu yric acid o ace ic acid and hydrogen. as erms in equa ions (3.41) and

(3 .42) are inpu s of propionic and n-bu yric acids from soluble organics . as

erms in equa ions (3.43) and (3.44) are ace ic acid and hydrogen from soluble

organics. There are few unknowns in equa ions (3.41), (3.42), (3.43), and

(3.44) which we need o find ou for he de ermina ion of o al propionic, n-

bu yric, ace ic acid, and hydrogen concen ra ion.

7 5

Page 87: Optimal Design and Operation of Wastewater Treatment Plants by

The ma erial balances for biodegradable solids hydrolyzers, acids oxidiz-

ers (propionic and n-bu yric), soluble subs ra e oxidizers, hydrogen consumers,

and me hane formers can be represen ed as :

where,

KDBD' KDP' KDB' KDS' KDH2' and KDM are he decay coefficien s for biode-

gradable solids hydrolyzers, propionic and n-bu yric acids and soluble subs ra e

oxidizers, hydrogen consumers, and me hane formers respec ively .

€BD' €P' NB' €, €H2, and €M are he grow h ra es for biodegradable solids

hydrolyzers, propionic, n-bu yric acid, and soluble subs ra e oxidizers, hydro-

gen consumers, and me hane formers, respec ively .

Andrews (1969) considered un-ionized vola ile acids as an inhibi ory

agen . This is because concen ra ions of un-ionized acids are func ions of pH

and o al acids concen ra ion. His model showed ha inhibi ion can be relieved

by main aining pH near neu rali y and/or reducing he organic loading . There is

some evidence ha hydrogen pressure of he order of 102 a mosphere are oxic

(dXBD ld ) _ (QII /VD )* (XBDO XBD )+(€BDKDBD ) *XBD

76

(3 .45)

(dXPT/d ) _ (QII /VD )* (XPTO XPT )+(g pKDP)*XPT(3 .46)

(dXBT/d ) _ (QII /VD ) * (XBTO -XBT)+(p.BKDB )*XBT(3 .47)

(dXS /d ) = (QII /VD )* (XSO XS )+(€KDS)*XS(3 .48)

(dXH2/d ) = (QII /VD) * (XH2O XH 2)+(1 2)+(1U -KDH2)*XH 2(3 .49)

(dXM/d ) = (QII /VD )* (XMO XM)+(€M-KDM)*XM(3.50)

Page 88: Optimal Design and Operation of Wastewater Treatment Plants by

o he organisms media ing he urnover of propiona e and will re ard he fer-

men a ion of ace a e o me hane (Shea e al. 1968). Because of his evidence

hydrogen inhibi ion is included in propionic, n-bu yric, and ace ic acid grow h

ra e equa ions.

The inhibi ion by un-ionized acids have been incorpora ed in o he

Monod grow h kine ics as follows :

where,

TA = o al un-ionized acids concen ra ion, MI S , = PA+NBA+HA

TACID= o al acids concen ra ion, MI 3 ,

PA NBA HADMU =

+

+KIP K 1B K 1A

KSp , KSB , KH 2, KT , KSBD , and KS are sa ura ion coefficien s for pro-pionic, n-bu yric acids,

7 7

€P = €P /(1+KSP/PA+DMU+H21KH2I,)(3 .51)

*

,NB = €B l(1+KSBINBA+DMU+H2/KH2 )(3.52)

*

€H = €H /(1+KH2/H 2+DMU)(3 .53)

*

€M = €M /(1+KTA/TA+DMU+H2/KH2 ,)(3 .54)

*

€BD = €BD /(1+KSBD/BD)(3 .55)

€ = €/(1+KS /S +TACID /KSI )(3 .56)

Page 89: Optimal Design and Operation of Wastewater Treatment Plants by

where,

HTA

=

o al ace ic acid concen ra ion, MI 3,

PTA

=

o al propionic acid concen ra ion, MI 3,

NTA

=

o al n-bu yric acid concen ra ion, MI 3 ,

KKAC

=

ioniza ion cons an of ace ic acid,1 .738x 10 a 25‚ C

hydrogen, o al un-ionized acid, biodegradable solids, and soluble organ-ics, respec ively .

K 1P , K 1B , K 1A , KH,, , and KS, are inhibi ion coefficien s for propionic,n-bu yric, and ace ic acid,

hydrogen, and soluble subs ra e respec ively .

HA = un-ionized ace ic acid concen ra ion, MI 3,

PA = un-ionized propionic acid concen ra ion, M/ 3,

NA = un-ionized n-bu yric acid concen ra ion , MI 3 .

The un-ionized acids concen ra ion can be calcula ed using he equilibria

KPAC ioniza ion _ons an of propionic acid,1 .349x 10 a 25‚ C

78

for acids .

HA = (H+)(HA)l(KIIAC ) (3.57)

PA = (H+)(PA)l(KPAC ) (3 .58)

NBA = (H+)(NA )l(KNBAC) (3 .59)

HTA = HA +HA(3.60)

PTA = PA +PA(3.61)

NTA = NBA +NA(3.62)

Page 90: Optimal Design and Operation of Wastewater Treatment Plants by

KNBAC

ioniza ion ons an of n-bu yric acid,1 .479x 10-j a 25‚ C

The above equa ions can be solved only by proper analysis of carbona e sys em.

E.2. Carbona e Sys em and pH

The de ailed descrip ion of carbona e ma erial balances and calcula ion

of pH is presen ed in Hill and Barh (1977) and Graef (1972) . The formula ion

is presen ed here wi h some modifica ion.

where,

(CO 2)D

=

dissolved CO 2 concen ra ion, M I3 ,

K 1

=

ioniza ion cons an for CO 2 , 3.98 X 107-7 a 25‚C .

The ne ra e of mass ransfer be ween he gas and liquid phase can be expressed

by wo film heory .

The carbonic acid equilibrium is given by :

CO 2+H20 HCO 3 +H +

C02S

KA

K1= (H+)(HCO 3)l(CO 2)

(dCO 2 /d )T =KA (CO 2S - CO 2 )

CO 2S = KCO 2 *PCO 2

sa ura ion concen ra ion of CO 2 , MI3 ,

gas ransfer coefficien , T 1,

79

(3 .63)

(3 .64)

(3 .65)A equilibrium, he CO 2 concen ra ion in he liquid phase is propor ional o he

par ial pressure of CO 2 in he gas phase. Therefore,

where,(3.66)

Page 91: Optimal Design and Operation of Wastewater Treatment Plants by

where,

H2S

KCO2 Henry's law constant,3 .23x 10-', moles/mm Hg .l at 25€ C ,

PCO 2

=

partial pressure of CO 2 in gas phase, mm Hg .

The PCO 2 material balance equation is :

(dPCO 2/dt) = - (TP)*D* (VD /VG)(dCO 2/dt)-(PCO 2/VG)*Q

where,

Q

= QCH4 +QCO 2 +QH2

QCO 2

=

CO2 gas production, /T ,

QCH4 = CH4 gas production, /T,

TP

= total pressure of CO and CH in gasstorage unit, assumed 0 mm1Ig,

D = conversion factor for changing moles ofgas to liters at ambient temperature andpressure,

VG

=

gas storage volume, ,

VD

=

volume of the digester, .

QH2 = - (dH 2/dt)*VD*D

Similarly, the net hydrogen transfer between the gas and liquid phase can be

expressed as ;

KA 1

MH2

d(H2/dt) =KA1* (H2S-H2)

saturation concentration of hydrogen, MI ,•

KHH *PH2*MH22

gas transfer coefficient, T-1,

molecular weight of hydrogen,

0

(3 .67)

(3 .68)

(3 .69)

(3 . 0)

Page 92: Optimal Design and Operation of Wastewater Treatment Plants by

PH2

KHH2

partial pressure of hydrogen in gas phase, mm Hg .

Henry's law constant of hydrogen, moles/mm Hg .l

The PH2 material balance is expressed as,

(dPH2/dt) = -(TP*D )* (VD /VG)* (dH2/dt) -(PH 2/VG )*Q

The rate of methane formation is given by :

RCH4 = YCH4X * ‚M *XM

where,

YCH4X = yield coefficient of methanogens.

Rate of methane entering the gas phase is equal to the rate at which methane is

produced because methane is almost insoluble. Therefore,

( . 1)

( . 2)

QCH4 = (YCH4X * R'M *XM/XMW+(‚H *XH2/YXH2)*YMH/CH4M)) *D*VD( . )

The rate of biological production of CO 2 is given by :

RCO 2 = YC02X * NM *XM

where,

YC02X = carbon dioxide yield coefficient,moles of CO 2/moles of organism .

The rate of CO 2 escaping into the gas phase is represented by :

QCO2 = (dCO 2/dt )T *VD*D

The rate of CO 2 formation by methane formers is written as :

(dCO 2/dt )M = (‚M *XM*YC02X )IXMW

where

1

( . 4)

( . )

( . )

Page 93: Optimal Design and Operation of Wastewater Treatment Plants by

CH4M

= molecular weight of methane,

XMW

= molecular weight of microbial mass .

The rate of production of CO 2 form HCO by acids (propionic, n-butyric, and

acetic acid) formers (chemical) is represented as :

where,

(dPT/dt), (dNT/dt), and (dHT/dt) are material balances of

propionic,n-butyric and acetic acids, MI T .

The rate of CO 2 production from HCO by cation formation can be written as :

where,

z+ = net cation concentration,except H +, eq / .

The rate of CO 2 production (biological) is written as :

(dCO 2/dt )BDC = (‚BD *XBD /YXSO)*YCO21 + (‚*XS /Yxs )*Yco22

The charge balance requires the following differential :

(dCO2/dt )NH4 = (dNH4 /dt )

where,

dNH4 /dt

(dCO 2/dt )C = dZ+/dt

(dZ +/dt) = (QII /VD )* (ZI - Z+)

_ (QII/VD)*(NH4INNH4) + ‚*XS*YNH4

2

( . 0)

( . 1)

( . 2)

( . )

(dCO 2/dt )PT = dPT /dt( . )

(dCO 2/dt )NT = dNT /dt( . )

(dCO 2/dt )HT = dHT /dt( . 9)

Page 94: Optimal Design and Operation of Wastewater Treatment Plants by

NH4IN

NH4

yield coefficient of ammonia fromraw waste, mg NH4/mg of organism,

influent ammonia concentration, MI ,

effluent ammonia concentration, MI .

(HCO ) concentration is required before the carbonate equilibria is established

to calculate pH . The balance between cations and anions are required in order

(dCO 2/dt) _ (QII /VD )* (CO 21N-CO 2)+(dCO 2/dt )M + (QII /VD )

* (HCO 1N HCO )+(dCO 2/dt )T +(dCO 2/dt )HT

+(dCO 2/dt )PT+(dCO 2/dt )NT-(dCO 2/dt )C +(dCO 2/dt )NH4

+(dCO 2/dt )BDC

where,

CO 21N = influent dissolved C0 2 concentration, MI ,

C0 2 = effluent dissolved CO 2 concentration, MI ,

HCO 1N

= influent HCO concentration, MI ,

( . )

to find the (HCO ) concentration. The charge can be written as :

(NH4 )+(H+)+(C+) = (HCO )+2(CO2 )+(HA )+(PA )+(NA )( . )

+(OH)+(A )

For pH in the range of to , the above equation becomes :

(NH4 )+(C+)-(A ) _ (HCO )+(HA )+(PA )+(NA )( . )

(HCO )=(Z+)+(NH4 )-(HA)-(PA)-(NA )( . )

Therefore, the material balance of carbon dioxide used is :

Page 95: Optimal Design and Operation of Wastewater Treatment Plants by

HCO effluent HCO concentration, MI .

The summary of the mathematical model and information flow indicat-

ing the interaction between the three phases in the system is given in Figure

.11 .

F. Optimization Description

Optimization of the treatment plant is accomplished through a minimiza-

tion of the objective function, formulated as a weighted sum of capital and

operation and maintenance (fixed and variable) costs . The objective function is ;N

N

TC =

(CCOSTk 1/r) +

(OMk 1 + VOPCk 1)k 1=1

k 1=1

( . 9)

where,TC

=

the total discounted cost,

CCOSTk 1

=

capital cost of unit kl,

OMk 1

=

operation and maintenance cost of unit kl,

N

=

total number of cost functions considered,

F

=

a discount factor, defined as a function ofdiscount rate, i, and number of years,n 1 , in the planned horizon .nl

( .90)j=1

VOPC

=

variable operating cost .

For the dynamic operations of a plant, process energy costs are not constant .

For this reason the variable operating cost has been included in the objective

function .

Page 96: Optimal Design and Operation of Wastewater Treatment Plants by

VD. VG

TP. D

011.0

NH41N

21, VD

KA

KA1

C02IN

HC0 IN

KHH2

KHAC

KPAC

KNBAC

YPACS

YNBACS

YXPAC

YXNBACYC

K1

CGntd .

O

PC02

PH2

2+

NH4

(C02)

PAC

NBAC

HAC

H+

HC0

PC02 - -(TP • D) •GAS PHASE

(VDNG) • (CO2)T - (PC02NG) • 0PH2 --(TP • D) • (VDNG) • (H2)T- (PH2NG) • 00 -OCH4 +0002

D0002 --(002)T

+ OH2

VD OH2 --(H2)T • D • VD

PCO2tPH2 OCH4 ,

1(C02)T 1 (H2)T

IQUID PHASE

F;r - CON - RXN11 + RXN21 • YPACSNBT - CON - RXN 1 + RXN21 • YNBACSHT - CON - (‚M •

XM/YXA) + RXN11 • (1- YXPAC) ' YAP

+ RXN 1 • (1 - YXNBAC) ' YANG + RXN21 • YHCSH2 - CON -(‚H •

XH2/YXH2 ) + RXN11 • (1- YXPAC ) • YHP+ RXN 1 • (1- YXNBAC) ' YHNB + RXN21 •YH2S + (H2 )T

RXN21 - (A • XS/YXS) •

(1 - YXS - YCO22)

RXN11 - (‚P • XPT/YXPAC) RXN 1 - G S • XBT/YXNBAC)

(C02)T - KA' (CO2S - C02)

HA

-(H+) (H)/KHAC

C02S - KC02 • PC02 PA

- (H+) (PA-)/KPAC

(H2)T - KA1 • ( H2S- H2)

NA

- (H+) (NA-)/KNBAC

H2S - KHH2 • PH2 HC0(H+) - K1 • C02/HC0 ) + (CO2)M + (C02)T(C02) - CON + (OIIND) •

(HC0 1N -

+ (C02)PT + (C02)NBT + (C02)HT + (C02)NH4 - (002)0

+ (CO2 )BDC(C02)PT - PT (CO2)NBT - NBT

(CO2)HT - HT

(C02 )BDC - (KBD' XBD/YXSO) ' YC021 + ( • XS/YXS) ' YCO22

(HC0 ) - 2+ + NH4+ -HA- -PA- -NBA-

AP A XPT A OCH4A‚BD TA PA

9B XBT ‚H TACID NBA‚ XS XM ‚M H2 HA

V

Page 97: Optimal Design and Operation of Wastewater Treatment Plants by

XPTXBTxs

4 OCH4

XM

‚BO‚H‚M

TATACIDH2

PANBAHA

BD

S

XBD

XPT

XBT

XS

XH2

XM

‚I0

‚Ap

‚B

‚M

‚HDMU

OCH4

CON

BIOOGICA PHASE

- CON - (‚BD • XBO/YXSO • CF)

- CON - ( ‚ • XS/YXS) + (‚BD • XBD/YxsD • CF) • OMYS1-CON + (‚BD - KDBD) •XBD

- CON + (‚p- KDB) • XPT

- CON + (‚B -KDB) •XBT

- CON + (‚ - KOs) 0 XS

- CON + (‚H - KDH2) •XH2

- CON + (‚M - KOM) • XM

- ‚BD/( 1 + (KSBD/BO ))

- ‚ •/ (1 + (KS/S) + TACID/KSI)

- ‚p/11 + (Ksp/PA) + OMU + H2/KH21 )

- ‚g/(1 + (KSS/NBA) + DMU + H2/KH21)

- 144/(1 + (KTA/TA) + DMU + H2/KH2 1)

- ‚H/11 + (KH2/H2) + OMU)

- (PA/Kip) + (NBA/K1 ) + (HA/KiA)

- ((‚M • XM/YCH4X) + (‚H • XH2NXH2) • YMH) • 0 • VD

- (O1WDI • (IN-OUT)

OMYS1- (1- YXSO - YC021 )

P- .XM-i

BD

S

XBD

XBT

XPT

xs

XH2

Fig . .11 Summary of Mathematical Model and Information Flow

Page 98: Optimal Design and Operation of Wastewater Treatment Plants by

To obtain a realistic optimum, constraints are required on many process

variables. Constraints are required because regulations or physically realizable

conditions through limits on linear or nonlinear functions of those variables .

where,

OVE nun

G

=

limiting solid flux of secondary clarifier,Kg /m /day,

minimum overflow rate, m /m 2/day ,

OVE

= overflow rate, m /m 2/day .

c. Constraint for anaerobic digestion :

(1) Constraint on sludge retention time :

O E)dmin

(2) Constraint on the maximum permissible loading :

( .94))

Constraints considered in this study are the following :

a. Constraint on the effluent suspended solid concentration .

XEFF <_ 0 gm /m( .91)

b. Constraints for secondary clarifier :

(1) For thickening :

Operating flux G( .92)

(2) For Clarification :

OVE >_ OVE nun ( .9 )

Page 99: Optimal Design and Operation of Wastewater Treatment Plants by

where,

ƒd

E)dmin

F md

Ud

Fd <_Fd

sludge retention time, days,

minimum solids retention time, days,

maximum permissible loading rate, Kg VSS /m day,

loading rate, Kg VSS /m day .

( .9 )

Cost functions (capital costs and O&M costs (excluding process energy

costs)) in terms of design variables for different unit processes are developed

using the data available in Patterson and Banker (19 1), and Smith (19 ).

Cost functions are to be updated to use in the present year .

Various indices are available for updating costs. For this research, the

most frequently used ENR Construction Cost Index (CCI) is used . Data avail-

able for energy and labor of different unit processes are in KWH/yr and hrs/yr,

respectively. So the updating using Construction Cost Index (CCI) is required

for only capital and maintenance costs .

The influence coefficient algorithm developed by Becker and Yeh (19 2,

19 ) is combined here with the minimum criteria to obtain a linear program-

ming formulation. Influence coefficient is used to cope with the nonlinearities

involved in the cost functions of the unit processes of treatment plant . The

algorithm requires the initial estimates of the parameters in the feasible region .

The error in the parameters are then optimized i.e., parameters are optimized to

minimize the objective function . The information flow diagram including the

optimization is shown in the Figure .12. The algorithm applied to the optimal

design and operation of treatment plant is outlined below :

Page 100: Optimal Design and Operation of Wastewater Treatment Plants by

OPTIMIZATION

(INFUENCE COEFFICIENT)

DESIGN AND OPERATING

PARAMETERS

DESIGN PROGRAM

STARTO

PARAMETERS

CW

(TRANSIENT PROGRAM)

FIXED PARAMETERS

Fig . .12 Information Flow Diagram for the east Cost Design andOperation

9

DESIGN

VARIABES

(E.G . OXYGEN TRANSFER, CHSUDGE PRODUCTION)

OBJECTIVE FUNCTION

CAPITA

COST

9

FIXED

OPERATING

COST

VARIABE

OPERATING

COST

Page 101: Optimal Design and Operation of Wastewater Treatment Plants by

1 . Initial estimates of the parameters in the feasible region are used for the

solution of the steady state model . The output obtained from the steady

state model is design variables . Each function of capital cost and operat-

ing and maintenance cost (fixed) for each unit process are functions of

design variables. Dynamic mathematical model solved by CSMP III .

calculates dynamic oxygen requirement, sludge production, and gas pro-

duction from anaerobic digestion . Variable operating costs are process

energy cost, sludge disposal cost, and the revenue by selling methane

gas. Values of each of the cost functions are calculated using design

parameters obtained from the steady state model . The error alk 1 and brk 1

are:

aA 1

bik 1

where,

k1

i

N

=

number of cost functions,

M

= number of parameters .

2. Mathematically, the objective function is ;

N

N

min[ I CCOSTk 1/I' + Y OMk 1 + VOPCk 1=1

k 1=1

[(Capital Costs Using Perturbed Parameters)-(Cost Using Parameter Estimates)] / Changes in Parameters)

(Fixed O&M Costs Using Perturbed Parameters)-(Fixed O&M Costs Using initial Parameter Estimates)] /(Changes in Parameters)

9 0

( .9 )

Page 102: Optimal Design and Operation of Wastewater Treatment Plants by

. Each parameters are perturbed independently in turn and the following

influence coefficient matrix is calculated ;

CCOST1CCOSTN OM1,OMN

ilp all a12 a1 alN bll b12 b1 blN

SRT a21 a22 a2 a2N b21 b22 b2 b2N

Od a 1 a 2 a a N b 1 b 2 b b N

OR a41 a42 a4 a4N b41 b42 b4 b4N

HRT a 1 a 2 a a N b 1 b 2 b b N

ORA a l a 2 a a N b 1 b 2 b b N

'y aM1 aM2 aM aMN bM1 bM2 bM bMN

91

Page 103: Optimal Design and Operation of Wastewater Treatment Plants by

4. Changes in the estimated values of parameters for the next

iteration is required. Therefore ;

rip

=

rip +a0

SRT

= SRT + a2

ƒd

= Od + a

OR = OR € + a4

HRT = HRT€ + as

ORA = ORA € + a

+ aM0

in which superscript 1 represents new estimations and are the perturba-

tions to be determined . A linear form is assumed for kith cost functions ;

CCOSTk1 = CCOSTk1 + a lk 1 .ai ++aMk 1 .a €' .9 )

OMk1 =OMk, +blk1 .a ++bMk1.aM( .99)

in which alk and b.k are appropriate influence coefficient values calcu-

lated in step . ai ' a2, a ' . . . . am are determined by substituting equa-

tions ( .9 ) and ( .9 ) in the objective function. The linear program-

ming formulation becomes ;

92

( .9 )

Page 104: Optimal Design and Operation of Wastewater Treatment Plants by

subject to :

„ (CCOSTk1 + a lk l .ai ++ aNk 1 .aM) <_ CCOSTk 1

t(OMk€1 +blkl .a1 ++bNk1.aM)SOMkl

CCOSTk l, OMk l, a1€ '"' -"''aM€ >_ 0

rip 1

<

lip

<

11 p U I

SRT1 < SRT < SRTU1

Od 1

Od

< Od 1

OR1 < OR < ORU1

HRT1 < HRT < HRTU1

ORA1 < ORA < ORAU1

N

Nmin { F (CCOSTk 1/F) T OMk 1 + VOPC

}k 1=1

k 1=1

y 1

< y

9

< yU 1

( .100)

( .101)

( .102)

( .10 )

The variables are CCOSTk 1, ai, a2,aa' OMk 1 and slack variables .

The quantities CCOSTk 1, a lk 1,a 2k 2aMk 1, and OMk 1 are known

computationally. Solution obtained from linear programming include

ai ' az,aa . Therefore, SRT, Od , OR, HRT, ORA y can be

calculated using equation ( .9 ) . This completes one cycle and this pro-

cedure (step 1-4) is repeated until the convergence criteria is satisfied .

Page 105: Optimal Design and Operation of Wastewater Treatment Plants by

IV. COST EQUATIONS FOR UNIT PROCESSES

The objective of this dissertation is to show that an initial design pro-

cedure which considers capital and operating costs, including costs calculated

from dynamic treatment plant models, reduces overall, life time plant costs . In

order to satisfy this objective, it was necessary to calculate typical treatment

plant costs . A search of all available treatment plant cost data was made with

the objective of creating a set of empirical equations describing costs as a func-

tion of key process variables, such as size .

Costs were divided into three categories : capital costs ; fixed operating

and maintenance costs, and variable operating costs . Fixed operating and

maintenance costs are costs unaffected by the plant's operating strategy . Vari-

able costs are substantially affected by treatment plant operations, such as aera-

tion energy costs as affected by SRT .

Cost equations for capital, operating, and maintenance costs, excluding

process energy, in terms of design variables for different unit processes, were

developed using the data provided by Patterson and Banker (19 1), Smith

(19 ), and Wasner et al . (19 ) . These costs do not include cost for special

site work, land, legal, general contractor's overhead and profit, fiscal and

administration . The fixed operation and maintenance costs include costs for

energy (building electrical energy related), maintenance materials, and labor .

The building energy requirements for each process are in terms of kW-hr/yr and

are calculated using an average building related energy demand. Maintenance

material costs include the cost of periodic replacement of component parts such

as valves, motors, instrumentation and other process items of a similar nature to

maintain good process operating conditions . These material costs do not

94

Page 106: Optimal Design and Operation of Wastewater Treatment Plants by

consider cost of chemicals for process operation . abor requirements include

both operation and maintenance labor and are represented in terms of hrs/yr .

Most engineers and planners are accustomed to updating costs using an

index which is developed by tracking the costs of specific items and proportion-

ing the costs according to a predetermined ratio . Most frequently utilized index

in the construction industry is the ENR Construction Cost Index (CCI), and

costs using this index can be updated as,

(Construction Costs x Current CCI )Updated Cost =

(CCI of the Year of Available Data)

(4.1)

The simplicity and ease of use of the ENR has made it popular with engineers

and planners, but is limited when used for for water and wastewater treatment

plant construction, because it does not include mechanical equipment, pipes or

valves that are associated with such construction. The approach which is util-

ized to overcome the shortcomings of the ENR indices are to apply specific

indices (e.g . EPA index for material and supply costs) and actual costs of labor

($/hr) and energy ($/kW-hr). Cost functions for the optimal design and opera-

tion of a treatment system are as follows :

Primary treatment (Screening, Grit removal, and Flow measurements)

CCOST = EXP [ .2 9 2 + 0 . 191 x ]* 1000 .(4.2)

OHRS = EXP [ . 9 2 + 0.2 09 x + 0.1 49 x 2 - 0.014 x ](4. )

XMHRS = EXP [ . 4 1 + 0.20 1 x + 0.0 4 x 2 + 0.02 2 x - 0.00441 x 4](4.4)

TMSU =EXP [ .2 + 0 . 9994 x - 0.2249 x2 + 0.1101 x - 0 .0110 x 4](4. )

9

Page 107: Optimal Design and Operation of Wastewater Treatment Plants by

x

=

In(Q)

Q

=

flow to the treatment plant, MGD,

CCOST

=

capital cost, $,

OHRS

=

operation man-hour requirements, man-hr/yr,

XMHRS

= maintenance man-hour requirements, man-hr/yr,

TMSU

=

total material and supply cost, $,

EERG

=

electrical energy required for grit removal, kW-hr/yr

EERMS

= electrical ener required for flow measurements andscreening, k/yr,

EER

=

total electrical energy required, kW-hr/yr .

where

x =1n (AREAP)

9

Primary Clarifier:

CCOST = EXP [ . 1 + 0 . 9 x + 0.0 4 x2 - 0.004 2 x ]* 1000.(4.9)

OHRS = EXP [ . 4 + 0.2 41 x + 0.11 x2 - 0.01094x ](4.10)

XMHRS = EXP [ .2 42 + 0.22 x + 0.122 x - 0.011 x ](4.11)

TMSU = EXP [ . 9 + 0 . 0 x ](4.12)

EER =EXP [11 .0 -1 .2 4 x + 0.1 x 2 - 0.004 x ](4.1 )

EERG = EXP [ . 0 4 + 0.2 4 x - 0. 44 x2 + 0.00 1 x 1(4 . )

EERMS =EXP [ .149 + 0.2 x - 0.0 x2 + 0.014 2 x ](4 . )

EER = EERG + EERMS(4 . )

where

Page 108: Optimal Design and Operation of Wastewater Treatment Plants by

Aeration :

CCOST = EXP [2.4144 + 0 .1 x + 0.0 4 4 x 2 - 0.002 x ] * 1000.(4.14)

CCOST 1= EXP [4.14 + 0 . 1 x 1 - 0.0 2 x 1 + 0.014 49 x ]* 1000(4.1 )

OHRS = EXP [ .900 + 0 . 2 x 1 + 0.0 909 x 1 - 0.0049 x , ](4.1 )

XMHRS = EXP [ .1 994 + 0.294 x 1 + 0.1 99 x 1 - 0.0409 x 1 + 0.00 x(4.1 )11

THSU = EXP [0. 21 + 0.4 20 x ]* 1000 .

EER = EXP [-12.12 + 10.9 9 x 2 - 2.02 x 2 + 0.1 1 x2

-0.00 1 x2 ]

where

AREAP = surface area, 1000 ft2 .

x

=

In(V)

V

=

liquid volume, 1000 ft ,

X 1

= In (BCAP)

BCAP

=

initial firm blower capacity, 1000 cfm,

OCRT

=

oxygen requirement, lbs of 0 2/day,

x 2

= In(OCRT)

X

=

In (QA)

QA

= flow to the aeration tank, MGD,

CCOST

=

capital cost of the aeration tank (basin structure), $,

CCOST 1

=

capital cost of diffused air system, $,

9

(4.1 )

(4.19)

Page 109: Optimal Design and Operation of Wastewater Treatment Plants by

9

Secondary Clarifier :

CCOST = EXP [ . 1 + 0 . 9 x + 0.0 4 x 2 - 0.004 2 x ]* 1000 .(4.20)

OHRS =EXP [ . 4 + 0.2 4 1 x + 0.11 0 x2 - 0.01094x ](4.21)

XMHRS =EXP [ .2 42 + 0.22 x + 0.122 x 2 - 0.0 11 2 x 1(4.22)

TMSU = EXP [ . 9 + 0 . 0 x ](4.2 )

EER = EXP [ .9 902 + 0. 2 x + 0.0111 x 2 - 0.000 4x ](4.24)

where

x =1n (AREAS)

AREAS = surface area of the secondary clarifier, 1000 ft2.

Anaerobic Digestion :

For digester volume < 20,000 ft

CCOST = EXP [4. 9422 + 0.12 24 x - 0 .0040 x2]* 1000(4.2 )

OHRS = EXP [ .1 + 0.1 0 x - 0.0124 x2](4.2 )

XMHRS = EXP [ . 2 9 + 0.11 x ](4.2 )

TMSU = EXP [ . 1 2 + 0.19 42 x + 0.021 x 2]

For digester volume > 20,000 ft(4.2 )

CCOST = EXP [ . 9 - 1 .949 9 x + 0.402 1 x2 - 0.01 21 x ] * 1000 .(4.29)

OHRS =EXP [9.1292 - 1 . 1 4 x + 0 . 2 x 2 - 0.01 29 x ](4 . 0)

Page 110: Optimal Design and Operation of Wastewater Treatment Plants by

where,

99

XMHRS =EXP [ . - 1 . 14 x + 0 . 1 x2 - 0.01 2x ](4 . 1)

(4. 2)

(4 . )

TMSU = EXP [ . 02 - 1 .1 2 1 x + 0.02 2 9 x 2 - 0.01 x 1

EER = EXP [12.4 - 2.0 9 x + 0.2 x 2 - 0.00 x ]

where

x = ln(DV)

DV = digester volume, 1000 ft .

Gravity Thickener:

COSTS = EXP [ . 2 9 + 0 . 9 9 x + 0.0 4 x 2 - 0.00 19 x

-0.00029 x4]* 1000 .

For EXP(x) < 1

OHRS = 0.

(4 . 4)

XMHRS =190.

(4 . )

TMSU=2 0.

(4 . )

For EXP(x) ? 1

(4 . )

OHRS =EXP [ . 4 + 0.2 4 1 x + 0.11 0 x 2 - 0.01094 x 1(4. )

XMHRS = EXP [ .2 42 + 0.22 x + 0.122 4 x2 - 0.011 2 x 1(4 . 9)

TMSU = EXP [ . 9 + 0. 0 x ](4.40)

EER = EXP [-12 . 0 + . 211 x - 0. 440 x2 + 0.0 0 4 x ](4.41)

Page 111: Optimal Design and Operation of Wastewater Treatment Plants by

x = In (AREAG)

AREAG = surface area of the gravity thickener, 1000 f t .

Recirculation and Intermediate Pumping :

For initial firm pumping capacity >- 1 MGD

CCOST = EXP [ .4 1 + 0 . 49 x + 0.09 x 2 - 0.00 22 x ]* 1000 .(4.42)

where,

x

= ln(QR)

QR

= recycle flow rate, MGD,

EERP

=

electrical energy consumed by recirculation and intermediatepumps, kW-hr/yr.,

EERMS

=

steady electrical energy (excluding pumps) required, kW-hr/yr .

10 0

OHRS = EXP [ .09 + 0.2 0 x - 0.19 x2 + 0.0 2 x - 0.00 x 41(4.4 )

XMHRS = EXP [ .911 4 - 0.01 1 x + 0.0 4 x 21(4.44)

TMSU = EXP [ .0 1 4 + 0. 01 1 x +0.19 1 x 2 -0.01 9 x ](4.4 )

EERMS = EXP [ .149 2 + 0.2 x - 0.0 x2 + 0.014 x ](4.4 )

EER = EERP + EERMS(4.4 )

Primary Sludge Pumping :

CCOST = EXP [-1 .44 + 2. x - 0. 2 x 2 + 0.02 x ]* 1000 .(4.4 )

OHRS = EXP [4. + 0 . 0 x - 0.0422 x 2 - 0.0019 x ](4.49)

XMHRS =EXP [1 . 9 + 1 . 9 x - 0.2 1 4x2 + 0.0141 x ](4 . 0)

Page 112: Optimal Design and Operation of Wastewater Treatment Plants by

TMSU =EXP [ 1 .1 09 - 1 .22 x + .0 994x 2 - 0.19 49x ](4 . 1)

EER = EERP + EXP [ .149 2 + 0.2 x t - 0.0 x 2 i + 0.014 x ,](4 . 2)

where

x

=

In (QI)

QI

= firm pumping capacity, GPM,

x 1

=

In (QI1)

QI1

= pumping capacity, MGD .

Capital costs and fixed operation and maintenance costs are calculated

using the average flow to the treatment plant and initial design parameters (pri-

mary clarifier overflow rate, solids retention time, hydraulic retention time,

digester solids retention time, and secondary clarifier overflow rate), and vari-

able operating costs, i .e. energy costs for oxygen transfer, sludge disposal costs

and revenue from methane gas, are calculated using the present energy cost and

sludge disposal cost. Costs using aforementioned cost equations and oxygen

requirements, sludge production, and methane gas from anaerobic digestion and

energy costs of $0 .0 /kW-hr and sludge disposal costs of $20/ton are shown in

Table 4.1 .

Most of the cost estimates depend upon initial designed parameters and

unit sizes shown in Table 4.2. These are obtained from the steady state design

of activated sludge process. In all cases, the dollar estimates are updated to

19 4.

Capital costs per year are calculated for an interest rate i = % and

planned project life of 20 years. Figure 4.1 shows the breakdown of costs (cap-

101

Page 113: Optimal Design and Operation of Wastewater Treatment Plants by

TMSU = EXP [ 1 .1 09 - 1 .22 x + .0 994 x2 - 0.19 49 x 1(4 . 1)

EER = EERP + EXP [ .149 2 + 0.2 x 1 - 0.0 x i + 0.014 x 1 ](4 . 2)

where

x

=

In (QI)

QI

= firm pumping capacity, GPM,

x 1

=

In (QI1)

QI1

= pumping capacity, MGD .

Capital costs and fixed operation and maintenance costs are calculated

using the average flow to the treatment plant and initial design parameters (pri-

mary clarifier overflow rate, solids retention time, hydraulic retention time,

digester solids retention time, and secondary clarifier overflow rate), and vari-

able operating costs, i.e. energy costs for oxygen transfer, sludge disposal costs

and revenue from methane gas, are calculated using the present energy cost and

sludge disposal cost . Costs using aforementioned cost equations and oxygen

requirements, sludge production, and methane gas from anaerobic digestion and

energy costs of $0 .0 /kW-hr and sludge disposal costs of $20/ton are shown in

Table 4.1 .

Most of the cost estimates depend upon initial designed parameters and

unit sizes shown in Table 4.2. These are obtained from the steady state design

of activated sludge process. In all cases, the dollar estimates are updated to

19 4.

Capital costs per year are calculated for an interest rate i = % and

planned project life of 20 years. Figure 4 .1 shows the breakdown of costs (cap-

1 01

Page 114: Optimal Design and Operation of Wastewater Treatment Plants by

Table 4.1 Cost Estimates for Unit Processes +

+ Cost estimates are updated to 19 4 dollars .

102

Capital Costs ($):

Primary Treatment screening, grit 0.2 1 x 10removal, and flow measurements

Primary Clarifier 0. 2 x 10Aeration Basin 0.40 2 x 10Diffusers 0. 44 2 x 10Secondary Clarifier 0. x 10Digester 0. 2 02 x 10Thickener 0. 4 4 x 10Recirculation and Mixing Pumps 0.1 4 x 10Sludge Pumps 0.4 001 x 10

Operation and Maintenance Costs ($/yr)Primary Treatment 0.4 00 x 10Primary Clarifier 0.242 0 x 10Aeration (Excluding oxygen transfer costs) 0.2 24 x 10Diffusers 0.2 094 x 10Secondary Clarifier 0.2049 x 10Digester 0.2 012 x 10Thickener 0.2 2 x 10Recirculation and Mixing Pumps 0.204 4 x 10Sludge Pumps 0.40 44 x 10

Variable Operating Costs ($/yr)Energy (Oxygen Transfer)

= 0.2 049 x 10Sludge Disposal

= 0.12 2 x 10Revenue from Methane Gas

= 0. 91 x 10

Page 115: Optimal Design and Operation of Wastewater Treatment Plants by

Input Parameter :

FlowInfluent suspended solids concentrationInfluent biochemical oxygen demandInfluent ammonia concentration

Initial designed parameteres and unit sizes :

Primary clarifier :

Overflow flow rate

=

10 0 gallons /ff 2/daySurface area

=

4 0.0 m 2Depth

=

10 ft (average)

Aeration Basin:

Table 4.2: Designed Parameters and Unit Sizes of ActivatedSludge Treatment Plants

Solids retention time = .0 daysHydraulic retention time = .0 hoursVolume

= 0.2 x 104 m

Secondary Clarifier:

Overflow rate

=

1000 allons/ff 2/daySurface area

= 4 4.4 m 2Depth

=

10 ft (average)

Gravity Thickener:

Surface area

= 400 m 2

Anaerobic Digester :

Volume

= 0 mRetention time

=

10.2 days

10

MGD = . m /hr•

1 0 mg /•

2 0 mg I•

2 mg I

Page 116: Optimal Design and Operation of Wastewater Treatment Plants by

NOTE : VOPC = VARIABE OPERATING COSTS

Fig. 4.1 Cost Breakdown (Capital fixed operation and maintenance andvariable operation)

1 04

Page 117: Optimal Design and Operation of Wastewater Treatment Plants by

ital, fixed operation maintenance, and variable operation) . Total cost per yr for

the treatment of a MGD wastewater is $0. 442 x 10 . Therefore, the cost

for treating 1000 gallons of wastewater is $0 . 0. As indicated previously this

cost does not include influent pumping, chlorination, chemicals, costs for legal,

fiscal, administration, laboratory facilities, and cost of land .

The costs generated in this dissertation may be different than the cost of

a typical treatment plant, since the costs shown here are a subset of the total

costs. Furthermore, site specific costs have not been included. The costs pro-

vided are sufficiently accurate for comparisons and optimization ; they should be

applied to specific conditions only with extreme caution .

Page 118: Optimal Design and Operation of Wastewater Treatment Plants by

V. RESUTS AND DISCUSSION

A. Simulated Primary Sedimentation Basin Performance

The model of primary sedimentation basin represented by non-steady

state diffusion equation along with a parameter at boundaries to describe the

rate of scouring and resuspension is presented earlier . Dynamically, the pri-

mary sedimentation basin is the first processing unit to act on the influent flow

and concentration . There are no feed-back loops involved in the primary sedi-

mentation, hence, the responses of this process to influent parameter changes

can be investigated independently of the dynamic responses of the remaining

processing units .

The non-steady state diffusion equation is solved using ADI (Alternating

Direction Implicit) method with a grid of 51 x 51 in x and z directions . The

equation is simulated together with the effect of scouring parameter under vari-

ous operating conditions (realistic influent flow rate and total suspended solids

concentration) based on the assumption of homogeneous turbulence

(E = EZ = E) and uniform horizontal velocity (u = constant ) .

The efficiency of primary sedimentation basin is highly dependent on the

settling velocity of suspended particles . The effect of settling velocity (We ) of

suspended particles on the efficiency of primary sedimentation basin is deter-

mined. The effect of horizontal velocity on removal efficiency is also deter-

mined and simulated results are shown in Figure 5 .1 and 5.2, respectively .

Figure 5.3 shows the relationship between efficiency and depth for vari-

able flow rate, constant width and constant volume of the sedimentation basin .

It is apparent from the curves that the depth of the basin cannot be designed too

106

Page 119: Optimal Design and Operation of Wastewater Treatment Plants by

0.02

0.04

0.06

0.08

0.10

0.12

0.14

0.16

0.18

SETT

ING

VE

OCIT

Y (W

P) C

MS/S

EC

Fig.

5.1 RelationshipBe

twee

n Ef

fici

ency

(%)

and

Set

tlin

g

Velocity,

W,,,

cms/

sec

Page 120: Optimal Design and Operation of Wastewater Treatment Plants by

u lbv }30

-

10-

Fig.

5.2 Relationship Between Efficiency (%) and Settling

Velo

city

, U,

cms

lsec

Settling Velocity -

0.0

5 cm

s/se

c

Height

.30

5 cm

s

Dispersion Coefficient

s3.8

cm2/

sec

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0

9.0

10.0

11.0

HORIZONTAVEOCITY

(CMS/SEC

)

Page 121: Optimal Design and Operation of Wastewater Treatment Plants by

651

EFFICIENCY(%) VS . DEPTH(C21S) FOR VARIABE FOW(CU .M/HR .)

400 60 . 800

DEPTH,CM5

1 09

1000

vow' =1803 M3

WIDTH = 14 .26 M.

Q1<Q2<Q34Q4<Q5<Q6<Q7<Q8

1200

Fig . 5 .3 Relationship Between Removal Efficiency (%) and Depth,cms (V,W : Constant)

1400

Page 122: Optimal Design and Operation of Wastewater Treatment Plants by

small. This result is expected because the mean horizontal velocity in the basin

increases as the depth decreases causing an increase in mixing and turbulence

and impact of water on particles of deposit . Therefore, depth is one of the most

important design parameter for the design of primary sedimentation basin . Fig-

ure 5.4 shows the relationship between efficiency and depth for fixed flow rate

and volume and variable width. In both Figures 5 .3 and 5.4 there exists an

optimum depth with maximum efficiency . Figure 5 .5 shows that the effluent

concentration is minimum (i.e. efficiency is maximum) at depth = 400 cms for

dispersion coefficient, Ex = 3 .59 exp(58.5*F) . The effects of variable flow rate

and concentration, as well as basin depth have been determined through simula-

tions.

The direct use of non-steady state diffusion equation in the main optimi-

zation program is difficult to use because it solution requires extensive com-

puter time. For this reason a regression model is developed to determine the

effluent concentration from primary sedimentation basin . The second order

model is

+ B 3*ENGTH + B 4*OVE + B 5*OVE 2(5.1)

where,

B = statistical parameter estimates .

Statistical parameters are shown in the Table 5.1 . The stepwise regression is

used here for the development of the above model and the multiple R-square

obtained is 0.9907.

110

Page 123: Optimal Design and Operation of Wastewater Treatment Plants by

N

Fig. 5 .4 Relationship Between Removal Efficiency (%) and Depth,cms (V,Q : Constant)

111

Page 124: Optimal Design and Operation of Wastewater Treatment Plants by

Fig. 5.5 Relationship Between Effluent Concentration and Depthwith Time for Variable Flow Rate and InfluentConcentration

11 2

Page 125: Optimal Design and Operation of Wastewater Treatment Plants by

Table 5.1 : Effluent Suspended Solids Model Parameters

113

Parameter Parameter Estimate

B 0 10.9884B 1 0.00247B 2 0.00861B 3 0.00849B 4 0.00096B 5 -0.1287

Page 126: Optimal Design and Operation of Wastewater Treatment Plants by

B. Simulation of Activated Sludge Process :

The mathematical model to simulate the activated sludge plant is

described earlier. This is described by a complex set of nonlinear, simultaneous

differential equations. The activated sludge is modeled as (a) a continuous flow

stirred tank reactor (CFSTR), and (b) a plug flow reactor (PFR), approximated

by three CFSTR's in series .

The biological model parameters and coefficients for the simulation of

heterotrophic bacteria is presented in Table 5 .2. Numerical values of these

parameters are the best estimates from the literature whenever these were avail-

able or it could be calculated . In certain cases there was no estimate of parame-

ters available in the literature and in these instances, parameters and coefficients

were estimated in such a way that the model should conform to well known

observations .

Table 5.3 presents the numerical values for the nitrification model.

Parameters used here are same as those proposed by Poduska (1972) .

The simultaneous nonlinear differential equations are solved usingnumerical techniques. Four integration methods have been used including vari-

able step methods for obtaining steady state results . Time requirements of dif-

ferent integration methods are different depending upon the values ofcoefficients and parameters. Finally, the variable step, Milne method is used

for its minimum time requirement .

The steady state solutions are obtained using the numerical valuespresented in Tables 5.2 and 5 .3. Average influent BOD 5 and suspended solids

concentration are 250 mg/l and 150 mg/l respectively . Influent particulate

11 4

Page 127: Optimal Design and Operation of Wastewater Treatment Plants by

Table 5.2: Parameters and Coefficients for Heterotrophic Bacteria

11 5

Terms Value Description

f *S 0 .5 maximum fraction of stored mass,

KT 0.005 Transport rate coefficient,1/gm.XA.hr.,

RS 0.001 Direct growth rate coefficient,1/gm.XA.hr.,

RH 0.01 Hydrolysis rate coefficient, hr. -1,

RXA 0.015 Storage growth rate coefficient,

Y 1 0 .60 Mass of XA produced per unit massof XA or SD utilized,

Y2 0.20 Mass of XI produced per unit massof XA destroyed,

Y3 1 .00 Conversion factor, gm of XS orSD/gm of XA.

Page 128: Optimal Design and Operation of Wastewater Treatment Plants by

Table 5.3: Parameters and Coefficients for Nitrifying Bacteria

11 6

Terms Value Description

€NS 0.02 Maximum specific growth rate of Nitrosomonas, (T-1 )

KDNS 0.005 Nitrosomonas decay coefficient, T-1

YNS 0.05 Yield coefficient, mass of Nitrosomonas formedper unit mass of ammonium nitrogen oxidized .

*€NB 0.04 Maximum specific growth rate of Nitrobactor, T-1

KDNB 0.005 Nitrobacter decay coefficient, T-1

YNB 0.02 Yield coefficient, mass ofNitrobacter formedper unit mass of nitrite nitrogen oxidized .

0.07 Ammonia nitrogen released in decay of XA,gm NHS -N/gm XA

Page 129: Optimal Design and Operation of Wastewater Treatment Plants by

substrate concentration, inert mass, and non-volatile solid mass are calculated

using the coefficient in Figure 3 .3. The ammonium influent concentration is 30

mg/l .

w

Different values of RXA, RH, KT, RSD, andfs are used for simulations

and RXA = 0.15, RH = 0.01, RSD = 0 .001, and KT = 0.005 are considered as

the properly adjusted parameters because it conforms well with the documented

observations. These steady state results are dependent on the size of solid

liquid separator and for the purpose of these simulations the size of the solid

liquid separator is considered adequate for thickening and clarification . Steady

state results of activated sludge process after final adjustments of parameters are

shown in Table 5 .4. Figures 5.6 and 5.7 show steady state mass (particulate,

active, stored, inert, and total) concentrations, soluble substrate concentration,

nitrite, nitrate, and ammonia concentrations at different sludge retention time

(SRT), days .

The model predicts essentially the same effluent concentration for sludge

ages above 6 days which is in agreement with the field observations . Therefore,

for defining an optimum sludge age for operation, the decision should be based

upon the criteria, such as the aeration capacity, sludge production rate, and

sludge thickening and production characteristics, rather than soluble substrate

concentration .

Figure 5.8 shows the steady state results for nitrification using the

parameters and coefficients shown in Table 5 .2 . It is observed from the Table

5 .4 that the washout sludge age for the nitrifiers is higher than washout sludge

age for heterotrophs .

Page 130: Optimal Design and Operation of Wastewater Treatment Plants by

4 .U

8.6

12.0

16.0

20.0

24.0SOIDS RETENTION TIME

118

Fig. 5 .6 Steady State Effluent Soluble Substrate Concentration, gm/m3

Page 131: Optimal Design and Operation of Wastewater Treatment Plants by

119

SOIDS RETBRION TIM (UT), D%YS

Fig. 5.7 Steady State Mass Concentrations (RXA- 0.15, RH - 0.01,RSD - 0.001, KT - 0.005, f; - .6)

Page 132: Optimal Design and Operation of Wastewater Treatment Plants by

10.0

15.0

20.0

25.0

30.0SOIDS RETENTION TIME(SRT), DAYS

Fig. 5.8 Steady State Effluent Ammonia Concentrations forVariable Solids Retention Tune (SRT), Days

1 2 0

5.0

Page 133: Optimal Design and Operation of Wastewater Treatment Plants by

Notes :

Table 5.4 Steady State Results of Complete Mixing Activated Sludge

Process Simulation.

RXA=K*RSD, RXA=0.15, KT=0 .005, RSD=0.001

1 2 1

Species

1 3

Solids Retention Time (SRI), Days

20 305 10 15

XA 321.7 892.9 1222.5 1650.7 1861 .8 1987.8 2130.4

XP 674.7 1642.0 2354.2 3636.7 4644.1 5530.7 6828.7

XI 343.1 1143.8 1989.1 4006.4 6018.9 8012.0 11064 .0

XS 109.8 155.9 172.9 192.8 202.3 208.0 214.4

XN 283.4 845.3 1388.4 2617.4 3812.6 4957.0 6704.6

XNS 3.9 x 107' 8.2x 103 6.9 x 102 6.7 40.7 46.7 52.3

XNB 3.5x 103 3.7x 1OF' 4.5x 1e 6.8x IC" 0.13 17.4 20.7

XT 1449.3 3838.6 5738.8 9486.6 12727.0 15738 .0 20238.0

S 1 30.8 11.0 7.95 5.82 5.14 4.8 4.48

SN 1 47.6 47.6 47.6 47.6 47.6 47.6 47.6

NH 41 25.9 25.76 26.0 16.88 0.676 0.554 0.474

N 21 6.5 x 1072 1.3 x 102 0.104 9.80 25.41 0.233 0.192

N 31 2.4x 103 3.3x 1e 3.5x 10- '0 4.4x le 0.89 26.34 26.71

Page 134: Optimal Design and Operation of Wastewater Treatment Plants by

C. Dynamic Characteristics of Anaerobic Digestion :

Parameters for this model were obtained from the literature whenever

they were available. In some cases they were calculated from the reported

stoichiometry or reaction rates. Many of the parameters are not available in the

literature and in these instances they were estimated in such a way that the

model would conform to well known observations. The biological parameters

and coefficients for the simulation of anaerobic digestion is presented in Appen-

dix A.

Effects of sludge retention time and loading rates are shown in Figures

5.9 - 5.12. In each case the model is operated for a sufficient period of time to

obtain steady state results . The response of effluent soluble substrate and

effluent biodegradable solids to organic and hydraulic loading is shown in Fig-

ure 5.9. Overloading situations cause soluble substrate to increase. If the over-

loading is too high, the process may be unstable, causing an increase in volatile

acids concentration, leading to increased un-ionized acids concentration and

reduced pH. Inhibition results in increased un-ionized volatile acids and possi-

bility of process failure . It can be observed that if QCH4, €M , and € are

decreasing and effluent soluble substrate is increasing, then there is a higher

probability for the failure to occur . If QCH4, €M , and € are decreasing and

percent of CO 2 and percent of H 2 are increasing then failure is ensue . Percent

of CO 2 and percent of H2 can be measured and both can be used as indicators

for process conditions . Gas production per unit of VSS destroyed, percent of

VSS destroyed, and pH decrease and total volatile acids (propionic, n-butyric,

and acetic), un-ionized acids, and percent of H2 increase at lower sludge reten-

tion time (SRT) as shown in Figure 5 .12 .

1 22

Page 135: Optimal Design and Operation of Wastewater Treatment Plants by

III

:11

11

111

.11

5 .0

10.0

15.0

20.0

25.0

30.0

SOIDS RETENTION TIME (SRT) . DAYS

Fig . 5.9 Steady State Effluent Concentrations (BiodegradableSolid (BD) and Soluble Substrate (S)) for VariableSRT, Days

123

Page 136: Optimal Design and Operation of Wastewater Treatment Plants by

.67-

.65

240

1

100.

I,

Fig . 5 .10 Steady State Volatile Solids Destruction, Gas FlowRate (QCH4, QC02, and QH2), andSpecific Growth Rate of Methanogens for Variable SRT,Days

174

,9 .0

18,0

.7 .0

v

.3 .0

.2.0

1.0

Page 137: Optimal Design and Operation of Wastewater Treatment Plants by

18 .

16 .

14 . -

v

4 . -

2 . .

5.0 10.0

15.0

20.0

25.0

30.0SOIDS RETENTION TIME(SRT) . DAYS

Fig . 5 .11 Steady State Un-ionized Acids Concentration (Acetic (HA),Propionic (PA), and N-Butyric Acids Concentration),and Bi-carbonate Concentration (HCO3) for VariableSRT, Days

125

;.A,

G Is

Page 138: Optimal Design and Operation of Wastewater Treatment Plants by

O

14 .

13 .

32 .

9 .

6

r

Q

1700

3w

6.9-

TV-

6.5 .

6.3

P

PR-

M--.0 10.0

15.0

20.0

25.0SOIDS RETEMION TIKE (SRT), DAYS

1 26

30.0

Fig . 5.12 Steady State Gas Production/VSS Destroyed, Total AcidsConcentration, pH, and % CH4 for Variable SRT,Days

.69

.67

.65

61

597_

.57

Page 139: Optimal Design and Operation of Wastewater Treatment Plants by

It is important to recognize that the results of simulations might be ade-

quate to show the qualitative validity of the model, but quantitative conclusions

are tentative until more accurate values of the parameters are established .

D. Optimization

The objective function used in the previously described optimization

procedure was based entirely upon cost. Amortised capital and operating costs,

and both fixed and variable operating costs were combined into a single func-

tion .

Three distinct exercises were performed using the optimization pro-

cedure. The first was to verify that global minimums could be obtained . The

second was to investigate the effects of the three major economic parameters :

labor, energy and solids disposal costs . The final exercise was to perform an

optimization on subsets of the objective function. This procedure was divided

into two parts: capital cost and fixed operating costs only, and variable operat-

ing and maintenance cost only. These two cases were then compared to results

obtained in the sensitivity study . The two cases of capital and fixed operating

costs, and variable costs only, are roughly equivalent to current design pro-

cedures, or operating procedures, respectively .

It is far too complicated, and perhaps impossible, to prove that the

objective function used in this dissertation has a global minimum . Therefore a

different approach was used to insure that a global minimum was obtained.

Several different sets of initial parameters were used, and results for the dif-

ferent sets were compared . For all practical purposes, the results were the

same. The final values of primary clarifier overflow rate (POFR), hydraulic

127

Page 140: Optimal Design and Operation of Wastewater Treatment Plants by

retention time (Oh ), and secondary clarifier overflow rate (OFR) remained vir-

tually the same for all values of the starting parameters . The other two parame-

ters, digester volume (DV) and solids retention time (SRT) changed slightly

with different initial conditions, but changes observed were less than 10%. If

the optimization technique increased SRT, DV was decreased . The two param-

eters were slightly correlated, and an increase in SRT was compensated by a

decrease in digester volume . The final cost for different starting conditions did

not vary by more than 1%. It has been assumed that global optimums have

been obtained for all results presented here .

Optimization of a 5 MGD wastewater treatment plant considering the

economic parameters shown in Table 5 .5 indicates that the size of the primary

and secondary clarifiers and aeration basin should be made as small as possible .

It all cases the upper constraints for these three parameters were active (1200

and 1000 gallons/ft2-day , three hours E),,) . As can be observed from Figure

5.13 the solids retention time (SRT) and digester solids retention time (•d ) are

2.4 and 12.1 days, respectively. The cost of wastewater treatment considering

the economic parameters in Table 5.6 is $0.2992 per 1000 gallons .

Sensitivity analysis of the economic parameters showed similar results .

The cost of electricity was varied and the impact of the increased cost on the

design parameters is shown in Figure 5.13. As in the previous case, the two

overflow rates and hydraulic retention time approached their limits . Increasing

SRT increases oxygen demand and reduces sludge production . Therefore, for

lower energy cost the solids retention time should increase with a correspond-

ing decrease in digester solids retention time . As expected Figure 5.13 shows

this trend.

1 28

Page 141: Optimal Design and Operation of Wastewater Treatment Plants by

Table 5 .5 : Economic Parameters Used for Optimal Design and Operation

1 29

Construction cost index

Material and supply cost index

246 (December 1984)

1610.18 (December 1984)

Discount rate 0.10185

Planning period

Interest rate

20 years

8%

Hourly labor rate $20.84/hr

Cost of sludge disposal $20.0/ton

Cost of electricity

Efficiency of converting heat valueof fuels to equivalent electrical energy

$0.05/Kw-hr

0.50

Page 142: Optimal Design and Operation of Wastewater Treatment Plants by

Fig.

5.1

3 Op

tima

l De

sign

and

Ope

rati

ng P

aram

eter

s wi

th Varying

Oxygen Transfer Costs

24.

1400

-7

2012

006

POFR

18^>

1000

5on

16800

4-

3dT

c'14

-600

y?3

.‚

‚4

'a

O

12-94

00

S v A2-

10.

200

-I

80

0 0.0

0.05

0.10

0.15

Cost

&iof

y($/

ai)

Page 143: Optimal Design and Operation of Wastewater Treatment Plants by

The effect of increased sludge disposal costs is shown in Figure 5 .14.

For increased cost, the optimization algorithm selected higher SRT's to reduce

the sludge production . Moreover, the digester volume increased resulting in

increased volatile solids destruction and further reduction in sludge production .

The influence of labor rate on design and operating parameters is shown

in Figure 5 .15. At lower labor rate the digester volume increased, creating

greater revenue from methane gas and less sludge production . This indicates

that the labor requirements for operation and maintenance of an anaerobic

digester is more than for an aeration basin .

In all cases shown in Figures 5 .13, 5.14, and 5 .15, the maximum solids

retention time for all ranges of all costs is less than 2 .5 days. In practice SRT's

are usually more than three days and less than ten days . To investigate higher

SRT the lower constraint was increased . This also caused nitrification to occur .

This case and the influence of higher cost of energy cost are shown in

Figure 5.16. The cost of treatment with energy cost at $0 .05/kW and the

increased lower constraint was $0 .3672 per 1000 gallons. This compared to to

$0.2992 per 1000 gallons in the previous case .

The most important objective of this research was to compare costs and

design and operating parameters for objective functions a) capital costs only, b)

capital costs and operation and maintenance costs, and c) operation and mainte-

nance costs only. Results of these aforementioned objectives are shown in

Table 5 .6 . This table indicates that the cost of treatment considering the objec-

tive function with capital and operation and maintenance costs is $0 .2992 per

1000 gallons compared to $0.3087 and $0 .3005 per 1000 gallons for objective

1 31

Page 144: Optimal Design and Operation of Wastewater Treatment Plants by

22 20 18 14

140Q

'

120 U' 600-

CiF

N

3SR

T

POFR

0 .0

10.0

20,0

30.0

40.0

50.0

60,0

70.0

COST OFSum

Disp

osp

($/TON)

Fig.

5.1

4 Op

tima

l De

sign

and

Ope

rati

ng P

aram

eter

s with Varying

Slud

ge D

ispo

sal

Cost

s

Page 145: Optimal Design and Operation of Wastewater Treatment Plants by

POFR

OR

10,0

14,0

18.0

22.0

ABOR RATE ($/MM)

Fig.

5.1

5 Op

tima

l De

sign

and

Ope

rati

ng P

aram

eter

s wi

th Varying

abor Rate

221400'

7-

201200-

6-

18a

loon

N5

n

N 16

~ 4'

ce14

600-

3-

12400 .

2

10200-

1

80

0

Page 146: Optimal Design and Operation of Wastewater Treatment Plants by

v 15 13 11 9 7 5

1200

.12 10

-

8 6 4 2 0

POFR

eb OFR

SRT

--,

0.0

0.05

COST OF ENERGY(:

/Iai

)0.

10

Fig.

5.1

6 In

flue

nce

of O

xyge

n Tr

ansf

er C

osts

on

Optimal Design and

Oper

atin

g Pa

rame

ters

for

Hig

her

SRT

Syst

ems

0.15

Page 147: Optimal Design and Operation of Wastewater Treatment Plants by

Table 5 .6: Comparison of Optimization Cases .

Notes :Case 1 : Objective function considering only capital costs .

Case 2 : Objective function considering both capital costsand operation and maintenance costs .

Case 3: Objective function considering only operation andmaintenance costs .

135

Cost Case 1 Case 2 Case 3

Total Capital Costs($/yr)

0.274663 x 106 0.25995 x 106 0.263625 x 10 6

Total Operating Costs($/yr)

0.288805 x 106 0.28609 x 106 0.284761 x 10 6

Total Costs($/yr)

0.563468 x 106 0.54604 x 106 0.548386 x 106

Cost$/1000 gallons

0.3087 0.2992 0.3005

Page 148: Optimal Design and Operation of Wastewater Treatment Plants by

functions with capital costs only and operations and maintenance costs only,

respectively. The table shows that using the dynamic plant models coupled

with cost functions that include both fixed and variable costs produces the least

cost design. Optimization using either the steady state models for operating

costs, or optimizing after plant construction produces a higher cost design .

136

Page 149: Optimal Design and Operation of Wastewater Treatment Plants by

VI: SUMMARY AND CONCUSIONS

The two major objectives of this dissertation were realized . A dynamic

model for the entire wastewater treatment system was developed. Process

dynamics were incorporated into cost estimates for the design and operation of

the treatment system. Secondly, an optimization technique was employed to

obtain the minimum, total discounted cost . Both fixed and variable costs were

considered in a single objective function .

The first step for development of the wastewater treatment plant model

was to obtain a realistic input functions . Time series data (influent flow rate,

BOD s, and TSS) were obtained and analyzed using Fourier transforms, and

from the Fourier coefficients an input function model was developed . Inputs

were also perturbed with random noise to obtain a realistic input condition .

The first unit process, the primary clarifier was modeled using a non-

steady state advection-diffusion equation, considering turbulence, deposit

resuspension and transient inputs (flow rate, BOD s , and TSS).

The dynamic model of the activated sludge process is capable of describ-

ing the rapid removal of substrates observed in contact stabilization, as well as

the lag in specific growth rate at high loading rates was used . This model

separates the removal of soluble and particulate substrates, and considers floc-

phase substrate storage . The model of the solid-liquid separator is based on the

solids-flux theory, as presented by Dick (1970) . A flux limit between layers in

the separator was used to insure that the limiting flux was not exceeded. The

relationship developed by Cashion (1981) was used to determine the effluent

suspended solids concentration .

1 37

Page 150: Optimal Design and Operation of Wastewater Treatment Plants by

The sludge treatment models included gravity thickening and anaerobic

digestion. The dynamic model of anaerobic digestion uses the new concepts of

acetoclastic methanogenesis. The model also considers Monod (1942) kinetics

with inhibition by un-ionized acids, and includes the carbonate material balance

for theoretical pH calculations .

Finally, the entire wastewater treatment system was optimized using the

influence coefficient method with total plant cost as an objective function . Cap-

ital, fixed, and variable operation and maintenance costs were included . Vari-

able operating costs are costs which are significantly affected by operating stra-

tegy, such as changes in mean cell retention time. Revenue from methane pro-

duction was also included .

A sensitivity analysis of economic parameters, i .e. cost of energy, cost of

sludge disposal, and labor rate, indicated that minimum sizes of the clarifiers

and aeration tank should be used . No correlation among these parameters was

detected. Solids retention times of the activated sludge process (SRT) and

digester (4d), however, have an inverse correlation ; when SRT increases the

volume of the digester decreases .

The optimization algorithm developed is capable of handling objective

functions with a) only capital costs, b) both capital and operation and mainte-

nance costs, and c) only operation and maintenance costs . The cost of treatment

is minimized if both fixed and variable costs are considered .

138

Page 151: Optimal Design and Operation of Wastewater Treatment Plants by

A. Conclusions

The following results and conclusions are noteworthy .

1 . A non-steady state advection-diffusion equation considering turbulence,

deposit resuspension, and realistic inputs was used to model the primary

clarifier. The solution of this equation indicates that the depth is an

important parameter, and that there exists a depth for which the

efficiency is maximum .

2 . A structured model of the activated sludge process was developed which

distinguishes between particulate and soluble substrates and includes

material balances on active, inert, stored, and non-volatile biomass . A

model of nitrification which includes material balances on Nitrosomonas,

Nitrobacter, ammonia, nitrite, and nitrate was also used . . These models

were coupled with a solid-liquid separator model .

3 . A dynamic model of anaerobic digestion was developed upon the new

concepts that methanogens do not metabolize organic acids, except ace-

tate and formate, and that hydrogen production and utilization has a cen-

tral position in the fermentation of acetate and formate . This model

includes material balances of biodegradable and non-biodegradable

solids, soluble organics, acids (propionic, n-butyric, and acetic) and

hydrogen, as well as biodegradable solids hydrolyzers, propionic acid,

n-butyric acid, soluble substrate oxidizers, hydrogen consumers and

methane formers. The model also includes inhibition by un-ionized

acids and calculates the theoretical pH considering carbonate equilibria .

4.

The optimization methodology predicts optimal design and operating

139

Page 152: Optimal Design and Operation of Wastewater Treatment Plants by

parameters for which the total discounted cost is minimum . This metho-

dology is also capable of predicting optimal design and operating param-

eters for proposed treatment plants, as well as for existing plants .

5 . The optimal design and operation of a 5 MGD wastewater treatment

requires that both clarifiers be designed with high overflow rates, with

low hydraulic and solids retention times of the aeration basin, and higher

digester solids retention time for anaerobic digestion.

6 . A sensitivity analysis of economic parameters such as cost of energy,

sludge disposal and labor shows no impact on clarifiers (primary and

secondary) overflow rates and hydraulic retention time, and an inverse

relationship between the other two parameters, SRT and O d .

B. Recommendations

In developing this methodology it became apparent that there is a need

for research in the following areas :

1 .

An improved design of a primary clarifier to consider the non-uniform

horizontal velocity in the basin .

2 .

Development of a better equation to calculate the effluent suspended

solids concentration from the secondary clarifier .

3 .

Experimental data from treatment plants should be collected to better

estimate the structured activated sludge process model parameters .

4.

Improve the dynamic anaerobic digestion model parameters with the

additional treatment data .

14 0

Page 153: Optimal Design and Operation of Wastewater Treatment Plants by

5 . The solid-liquid separator should be modeled incorporating a second par-

tial differential equation which describes the settling velocity as a func-

tion of concentration and compaction.

6.

Expand the dimension of the problem to include multiple sludge treat-

ment and disposal alternatives .

7 .

Incorporate implicit constraints on optimization parameters .

1 41

Page 154: Optimal Design and Operation of Wastewater Treatment Plants by

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14 5

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14 6

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86. N r itz, R.M. nd B .J. Ad ms, "Cost Optimiz tion of W stew terTre tment Pl nt Design Prelimin ry Design Including Sludge Dispos l,"

14 7

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W ter Poll. Res. J. of C n d , ol. 15, 121, 1980 .

87 . N ito, M., T k m tsu, T., nd .T. F n, "Optimiz tion of the Activ tedSludge Process Optimum olume R tio of Aer tion nd Sediment tionessels," W ter Rese rch, ol. 3, 433, 1969 .

88 . O'Rourke, J.T., "Kinetics of An ero ic Tre tment of Reduced Temper -ture," Ph.D. Thesis presented to St nford Univ., St nford, C liforni ,1968 .

89 . P rkin, G.F. nd R.R. D gue, "Optim l Design of W stew ter Tre tmentSystems y Enumer tion," J. S ni. Engr. Div ., ASCE, ol. 98, 833,1972.

90. P tterson, W.. nd R.F. B nker, "Estim ting Costs nd M npowerRequirements for Convention l W stew ter Tre tment F cilities," W terPollution Control Rese rch Series 17090 DAN 10/71, U.S . Environmen-t l Protection Agency, 1971 .

91 . Pfl ntz, P., "Perform nce of (Activ ted Sludge) Second ry Sediment -tion B sins", in Adv. in W ter. Poll. Rese rch, Proc. 4th Int. Conf., S.H .Jenkins (Ed.), N . ., Perg mon Press, 1969 .

92. Pl c k, O.K. nd C.C. Ruchhoft, "Studies of Sew ge Purific tion X II -The Utiliz tion of Org nic Su str tes y Activ ted Sludge," Sew geWork J., ol. 19, 423, 1947 .

93 . Podusk , R.A., "A Dyn mic Model of Nitrific tion for Activ ted SludgeProcess," Ph.D. Dissert tion, Clemson Univ., Clemson, S.C., 1973 .

94 . Porges, N., J sewicz, ., nd S.R. Hoover, "Princip l of Biologic l Oxi-d tion," In Biologic l Sew ge nd Industri l W stes, ol.1, B.J.McC e nd W.W. Eckenfelder (Ed.), Reinhold Pu ., N. ., 1956.

95. Powell, E.D., "The Growth R te of Microorg nisms s Function ofSu str te Concentr tion," Micro i l Physiology nd Continuous Cul-ture, 3rd Symposium, Her M jesty's St tionery Office, ondon, 1967 .

96 . Pretorius, W.A., "An ero ic Digestion - III, Kinetics of An ero ic Fer-ment tion," W ter Rese rch, ol. 3, 545, 1969 .

97. R hn, O. nd J.E. Conn, "Effects of Incre se in Acidity on AntisepticEfficiency," Industri l nd Engineering Chemistry, ol. 36, 185, 1944.

98 . Rex Ch in elt, "A M them tic l Model of Fin l Cl rifier," EPA Con-tr ct No. 14-12,194, 1972 .

99. Rich, .G., Unit Processes of S nit ry Engineering, John Wiley ndSons, Inc., New ork, 1963 .

100 . Ruchhoft, C.C. nd C.T. Butterfield, "Studies of Sew ge Purific tion -P rt IX., Tot l Purific tion, Oxid tion, Adsorption, nd Synthesis of

148

Page 161: Optimal Design and Operation of Wastewater Treatment Plants by

Nutrient Su str tes y Activ ted Sludge, Pu lic He lth Reports, 51, 468,1939 .

101 . She , T.G., Pretorius, W.A., Cole, R.D., nd E.A. Pe rson, "Kinetics ofHydrogen Assimil tion in the Meth ne Ferment tion," W ter Res., ol .2, 833, 1968 .

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103 . Shih, C.S . nd P. Krishn n, "Dyn mic Optimiz tion for Industri l W steTre tment Design," J. W ter Poll. Cont. Fed., ol . 41, 1787, 1969 .

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105. Siddiqi, R.H., Speece, R.E., nd R.S. Engel recht, "Effects of St iliz -tion Period on the Perform nce of Cont ct St iliz tion Process," 58thN tion l Meeting, Amer . Inst. Chem. Engrs., D ll s, Tex s, 1966 .

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110 . Smith R., "Prelimin

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149

Page 162: Optimal Design and Operation of Wastewater Treatment Plants by

Resuspension of Settling B sin," J. Env. Engr. Div., ASCE, ol. 100,883, 1974.

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119. Tr cy, K.D., "M them tic l Modeling of Unste dy St te Thickening ofCompressi le Slurries," Ph.D. Dissert tion, Clemson Univ., Clemson,S .C., 1973 .

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128 . eh, W.W-G. nd . Becker, "ine r Progr mming nd Ch nnel FlowIdentific tion," J. Hyd. Div., ASCE, ol. 99, No . H 11, 2013, 1973 .

1 50

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129 . Zehnder, A.J.B., "Ecolo y of Meth ne Form tion," in ter PollutionMicro iology, ol. 2, . Mitchell ed.), p. 349, John iley nd Sons,Inc., New ork, 1978 .

130 . Zinder, S.H. nd R.A. M h, "Isol tion nd Ch r cteristics of hermo-philic Str in of Meth nos rcin n le to se H -C0 2 for meth no-genesis .", App. nd Env. Micro iology, 38, 996, 1979. 2

1 51

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Appendix A Digester P r meters

152

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*€BD

0.0166

M ximum specific growth r te forsolu le su str te oxidizers,)/hr

0.018

M ximum specific growth r te forpropionic cid oxidzers, 1/hr

0.02

M ximum specific growth r te forn- utyric cid oxidizers, 1/hr

0.0166

M ximum specific growth r te formeth ne formers, 1/hr

0.045

M ximum specific growth r te forhydrogen consumers, 1/hr

KDBD

0.0001

Dec y coefficient for iodegr d lesolids hydrolyzers, 1/hr

KDS

0.0001

Dec y coefficient for solu lesu str te oxidzers, 1/hr

0.0001

Dec y coefficient for propioniccid oxidzers, 1/hr

0.0001

Dec y coefficient for n- utyriccid oxidizers, 1/hr

0.0001

Dec y coefficient for hydrogenconsumers, 1/hr

KDM

0.0001

Dec y coefficient for meth neformers, 1/hr

QII

41 .617

Flow r te, m 3/hr

*€p

*€B

*

€M

*

€H

KDP

KDB

KDH2

Appendix A

P r meters nd Coefficients for An ero ic Digestion .

P r meters

lue

Description

0.0125 M ximum growth r te ofiodegr d le hydrolyzers

hydrolyzers, 1/hr

153

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1 54

D QII*SR olume of the digester, m 3

G 10% of D olume of the g s of the digester, m 3

KSBD 3000.0 S tur tion coefficient foriodegr d le solids hydrolyzers, gm /m 3

KS 150.0 S tur tion coefficient for solu lesu str te oxidizers, gm/m 3

Ksp 2.0 S tur tion coefficient for propioniccid oxidizers, gm /m 3

KSB 2.0 S tur tion coefficient for n- utyriccid oxidizers, gm /m 3

K A 5.0 S tur tion coefficient for meth neformers, . gm /m 3

KII2 1 .0 S tur tion coefficient for hydrogenconsumers, gm /m 3

K 1p 40.0 Inhi ition for propionic cid, gm /m 3

K 1B 40.0 Inhi itiion for n- utyric cid, gm /m 3

K lA 40.0 Inhi ition for cetic cid, gm /m 3

KS! 2580.0 Inhi ition coefficient for solu lesu str te, gm /m3

KH2I 2.0 Inhi ition coefficient for hydrogen, gm /m 3

CH4x 47.0 Meth ne yield coefficient

H2 1 .05 ield coefficient of hydrogen consumers

MH 2.0 ield coefficient of meth ne

xso 0.05 Solu le org nic yield coefficient,gm of org nism / gm of solu le su str te

S 0.03 ield coefficient for cid formers

PACS 0.36 ield coefficient of propionic cid,gm of PAC / gm of solu le su str te

NBACS 0.386 ield coefficient n- utyric cid,gm of NBAC / gm of solu le su str te

Page 167: Optimal Design and Operation of Wastewater Treatment Plants by

ield coefficient, gm of org nism/gm of solu le su str te

ield coefficient, gm of org nism/gm of solu le su str te

ield coefficient of meth ne, gm oforg nism! gm of cetic cid

ield coefficient of HAC from PAC,gm of HAC/ gm of PAC

ield coefficient of HAC from NB AC,gm of HAC/ gm of NBAC

ield coefficient of hydrogen from PAC,gm of hydrogen/ gm of PAC

ield coefficient of hydrogen from NB AC,gm of hydrogen/ gm of NBAC

ield coefficient of hydrogen,gm of hydrogen/ gm of solu le su str te

ield coefficient of mmoni , gm ofmmoni / gm of org nism

ield coefficient of CO 2 from iodegr d lesolids hydrolyzers

ield coefficient of CO 2 from solu lesu str te oxidizers

ield coefficient of CO 2 from meth neformers, mole of CO 2/ mole of org nism

G s tr nsfer coefficient of CO 2 , 1/hr

G s tr nsfer coefficient of H2, 1/hr

Ioniz tion const nt of cetic cidt 25• C

Ioniz tion const nt of propionic cidt 25• C

Ioniz tion const nt of n- utyric cidt 25• C

Henry's l w const nt of CO 2, moles

155

PAC 0.02

NBAC 0.02

A 0.0466

AP 0.8106

ANB 1 .363

HP 0.081

HNB 0.0454

tl2S 0.010

NH4 0.1212

C021 0.05

CO22 0.050

C02 47 .0

KA 0.4167

KA 1 0.4167

KHAC 1 .738 x 10-5

KPAC 1 .349 x 10-5

KNBAC 1 .479 x 10-5

KCO2 3.230 x 10-5

Page 168: Optimal Design and Operation of Wastewater Treatment Plants by

mm Hg.l t 25• C

KHH2

0.9 x 10-6

Henry's l w const nt of hydrogen, moles/mm Hg.1 t 38 • C

K 1

3.98 x 10 -7

Ioniz tion const nt of CO 2 t 25• C

P

730.0

ot l pressure, mm Hg

D

22.4

St nd rd volume of g s, liter / mole t 25• CCF

10

conversion f ctor, gm of solu le su str te/ gm of iodegr d le solids .

156

Page 169: Optimal Design and Operation of Wastewater Treatment Plants by

Appendix B Computer Progr ms

Page 170: Optimal Design and Operation of Wastewater Treatment Plants by

C

SO ION OF HE AD EC ION-DIFF SION EQ A ION CONSIDERINGC

RB ENCE AND DEPOSI RES SPENSIONCCC

INI IA CONDI ION : 100 MG/C

BO NDAR CONDI IONS :C

C=100 MG/ FOR =0C

DC/D =O FOR =IMAC

EZ `DC/DZ+SCO R-* P*C=O FOR Z=0C

EZ*DC/DZ+ P*C=O FOR Z=HCCC

HIS PROGRAM SO ES O DIMENSIONA PARABOIC PAR IA DIFFEREN IAC

EQ A ION SING ADI(A ERNA ING DIREC ION IMPICI ) ME HOD .CC

HE PROGRAM IS DE EOPED B PRASAN A K . BH NIACC

HE PARAME ERS ARE :C

IMA : N MBER OF RO S OF NODES IN HE GRID,C

JMA : N MBER OF CO MNS OF NODE IN HE GRID,C

KMA : N MBER OF IME S EPS,C

D : IS DE A , GRID SIZE IN HE DIREC ION,C

DZ : IS DE A Z, GRID SIZE IN HE Z DIREC ION,C

D : IS DE A , HE SIZE OF HE IME S EP,C

C1(I,J) IS HE A E OF HE SO ION . A( ),B( ),C( ) AREC

COEFFICIEN S RESPEC I E , ON HE O ER,MAIN AND PPER DIAGONAS .C

D( ) IS HE RIGH SIDE OF A =D .COMMON AS ,I,J,KP S1,C1(51,51),A(60),B(60),C(60),D(60)DIMENSION CO1(51,51),DO1(51,51),ECONC6(200),H1(200),Q1(200)DIMENSION SCONC2(4),ECONC2(51),H E1(200), MA 1(200),E 1(200)DIMENSION ID H1(200),SSIN1(200),O E1(200),ECONC7(200)IN EGER E ENREAD(15,100) APHA,BE A1,H E,HEIGH , P,CO, MA ,BC1

100

FORMA (6F8 .4,F8 .3,F8 .4)READ(15,105) DENS ,PSDGE, ID H

105

FORMA (2F7 .2,F8 .2)RI E(6,121) APHA,BE A1,H E,HEIGH , P,CO, MA ,BC1

121

FORMA (7(F1O .5,3 ))RI E(6,122) DENS ,PSDGE, ID H

122

FORMA (3(F10 .5,3 ))SSA =150 .

QA =788 .54GACC=981 .0IMA =51JMA =51DO 200 I=1,IMAREAD(15,111) (C01(I,J),J=1,JMA )

111

FORMA (6E13 .5)200 CON IN E

0=1802 .689E+06DO 202 I=1,IMADO 202 J=1,JMAD01(I,J)=CO1(I,J)

1 58

Page 171: Optimal Design and Operation of Wastewater Treatment Plants by

6S

(ZHOIHrHZIM:9‚')/'OOr='ISAH

./,=il

iz/'=zzZz=zO'OO=I

Z/'I=IZ(-Hf)/IHOISH=Z

/'=Zr=x

(-viNI)/vwx=0'O=NIHd

'O=SAI'I7INI OHZOI=SI4SHI ISS' ' 0

9‚=NNHIS ONO SHIHSI'ISISS

0(//Z'OJ',=2ISffN.S'IOSd, `SZ//9

Z'9d',=SONI HZONS'I NIS,`SZ//S' Ol i',=2ISIHd ONIHn00S,`SZS//'83`,=OS/z;rO NI INSIOId3S00 N0IS2ISdSI,`SZ//I'8d`,=7/OE

NI IS'INI SHZINNISSQNSdSfS JO NO2NSON00,`SZ//S'‚i‚`,=O3S/SOSSSilldO)I00'IA ONI'3S,`SZZ

//Z'83` ,=H.d3(I NIS8, `'7"7'9d',=OSS/SONI A.I00'ISA IINOZIHOH,`SZ//Z'S3`,=n,'O‚`Z'S3`,=HdZv,`SZ///).vw?odoO

S'IOd``Hn00s`S`00`dM`1HOIH`'IAH`1'HdI(ool`9)IIM(,IHOISH'ISHfIA `HIQIM'IHvInIA ,`OZ/)IvwrodiZ‚

(Z‚i`9)lnIMS/(vNx-'IAH)=.'IOd

o '=moos(I1nOOS) dS*Hd'I=xno3S

(/v,g) -=uIn00s=(i)

(‚Nn2id) d=6 S'‚=ZAH=()ZSAH'IAO=()'IAO

(vr4x. HlIM) /'7O''7Z:M=ZSAo(.HOISH-HZIM=9‚')/' oo:,:='IAH

(S'‚I',=HION'I,`'7`S'‚iS`,=IHOISH,`'7`S'‚`,=HIQIM,`O/)INHO36O'IHOISH`H.GIM (6 01'9)1IHM

nNIINOOCOZ(r`I)O=(f`I)i00xvwr'=r ‚oz oxvwI`=I‚oz o

vw=(i)vw(IHOIH*HIGIM) /'IOA=v

(IHOIHm00O)I2Is=NnHd,HOIH=()HNISS=()NISS

=IIi=SIIS=()

AC'SSI=NISSA=‚Z

'SZ‚=IHOIHnNN00ZOZ

Page 172: Optimal Design and Operation of Wastewater Treatment Plants by

091

(,HJIHH;=1aIM*9€')/' OOT*a='IaAH

,Q/'T=TZQ

TZQ/'T=ZZQza*za=TZQ0' 00T=.Q

Za/'T=TTZQ(T-XvWf) /JHOI3H=Za

TXQ/'T=ZXQXQTXa=TXQ

(T-XvwI)/XvwX=Xa0 'O=N I?Id

0=3W A'I'IVINI O?IHZ O, =3W 3H ,3S' ' 0

9 €=XVWNHZIS (II?IJ HHZ HSI'IgV,SH

0(//Z'OT3`,=?IHgWf1N Z3'IOHd,`XSZ//9

Z'83`,=SWO NI HJ NH'I NISVU, `XSZ//S'OT3`,=aiZHWv?Ivd9NI?Ifl00S, `XSZS//T'83`,=035/Z;=WO NI N3IOI33300 NOISZI3dSIa,`XSZ//T'83`,=7/9W'

NI ,3'INI HH. ZH J.NHNIa S (IaQN3dSAS 3O NOv?NHON00, `XSZ//S'€TH€`,=035/SWO SS HH, 3O A.IOOZHA JNI'IJ.HS, `XSZZ

//Z' 83` ,=H,daa NISVg,`X'7"7'83` ,=3aS/SWO NI A.IOOZHA 'IV.NOZI?IOH, T`XSZ//Z' S3` ,=5'ZHg, `XO€ `Z' S3` ,=~1Hd'I~1, `XSZ///).f1W?I03OOTT

Z3'IOHd`XHIdX`Hf100S`X3`00`dM`ZHOI3H`'I3AH`TVJ,Hg`VHd'IV(OOTT`9)3.PIM(,.HOIHH 3'IgVIlIVA`H.QIM H'IgvI?IvA,`XOZ/).VWHOJTZ€T

(TZ€T `9) HZI?IMXH/(XvWX*rIHAH) =HZ03d

0' T=Hfl00S(T?Ifl00S) dX3;-HHd'V=?iflO3S

(XH/Tv. H)-=T?Ifl00SXH=(T)TX3

(€NQrI) dXH;=6S' €=X3'IaAH=(T) T'IaAH'IHAO=(T) T'IHAO

(Xvwx-H.QIM) /'70 H''7Z*a='IHAO(.HOIHH;=H.QIM*9€')/' 00T;-b='IHAH

(S'€TH` ,=H.ON3'I, `X+I`S'€TH` ,=.HJI3H, `X'7`S'€TH` ,=H.QIM, `XOT/).VW?i036T0TXvwX`.HOIHH`H.QIM (6TOT`9)aI?IM

3f1NI.N00

€OZ.(f`I)TOQ=(f`I)T00Xvwf `T=f €OZ OaXVNI `T=I €OZ OQ

XvrX=(T)TXHWX(.HO I HH;=HQ I M) /'I OA=XvwX

(,HOI3H;-00V0),?IRS=TNQflHd.HOIHH=(T)TH

NISS=(T)TNISST=II

T=HWHb=(T)Tb

AVSS=NISSAVb=b€ZT

'S Z €=,HOI HH3f1NIZN00

ZOZ

Page 173: Optimal Design and Operation of Wastewater Treatment Plants by

OVE=Q*24 . E 04/ (WIDTHXMAX)FRUDN2=HVE/FRUDN1FRUDN3=58 .5*FRUDN2EX=3 .59*EXP(FRUDN3)EZ=EXEZ1=1 ./EZFRAC1=2 .*DT1FRAC21=EZ*DZ2FRAC2=2 .*FRAC21FRAC3=FRAC1+FRAC2FRAC31=FRAC1-FRAC2FRAC4=WP/(2 .*DZ)FRAC5=(-FRAC4-FRAC21)FRAC6=-FRAC21+FRAC4FRAC7=HVE/(2 .*DX)FRAC8=EX*DX2FRAC81=2 .*FRAC8FRAC9=FRAC7+FRAC8FRAC10=FRAC1-FRAC81FRAC12=FRAC1+FRAC81FRAC14=WP*SCOUR*DZ11FRAC15=WP*WP*SCOUR*EZ1FRAC16=FRAC3-2 .*FRAC14+FRAC15FRAC17=FRAC31+2 .*FRAC14-FRAC15FRAC18=FRAC31-2 .*WP*DZ11-WP*WPI .EZ1FRAC78=-FRAC7+FRAC8FRACYI=FRAC3+WP*WP*EZ1+2 .*WP*DZ11FRACY2=2 .*DZ*SCOUR*EZ1FRAC 8 8=FRACY2:;WPFRAC19=-FRAC8+FRAC1-FRAC7.FRAC20=FRAC8+FRAC1+FRAC7FRACY3=2 . -•WP*DZ*EZ1CFACT1=0 .000001

C

INITIA BOUNDARY CONDITIONBC=COJAST1=JMAX-1JAST=JMAX-2AST=IMAX-1IMAX1=IMAX-2JMAX1=JMAX-19IMAX2=IMAX-4

C

K=1, DEFINES AN ODD TRAVERSAC

K=2, DEFINES AN EVEN TRAVERSA OF THE GRIDDO 220 KPUS1=2,KMAXSCONC3=0 .0ECONC3=0 .0K=KPUS1-1EVEN=K/2EVEN=EVEN*2IF(K .EQ .EVEN) GO TO 300

C

THE FOOWING SEGMENT IS EXECUTED FOR THE ODD VAUES OF K .C

THE INET BOUNDARY CONDITION .STEP=1 .0

161

Page 174: Optimal Design and Operation of Wastewater Treatment Plants by

8Ov2Id(TZSH'If'ZI)TOOT+OTOVHJ*(T.SV"Il' I)Too+60Vx3T(T.SV"If'T I)T00=(T.SV'Ir)Q

0'0=(T.Sv'Ir)0TA0Hx3=(T.SS"If)SZ0vx3-=(TZSV'If) v

NOIOINOO AIHQNIIOH 2IOIlta.Xa MH,

0SfNNOOOSZ

8DVHd =(f`ZI)TOO+OTDVNJ*(f'I)Too+60VHJ*(f`TI)100=(f)QSOvxd=(r) o€0fIx3=(f) a9OV Id=(f)V

.sv'Ir' €=r osz oaQIHO aH.30HOIxaNI ani

08DVHJ =(f'ZI)TOO+OTDVHJ*(f`I)T00+60VHJ*(f'TI)TOO=(Z)a

ZO'x3-=(Z)o9T0vx3=(Z)a

o o=(z)vT+I=ZIT-I=TI

Z=r.SHT'€=I 017ZOQ

(da.S)va.I.'I'Iv08 0Hx3r (T.SVUf'Z I) T 00+0 TDVHJ=(TZSH'Tr'I) T00+60VHJ*T Og=(T ZSH'if)Q

0 '0=(TZSv'If) oT AOVx,I=(T.SwIf) HZ3Vx3-=(T.SWIf) H

HflNN00T€Z8 DVHJ* (f'Z I) T 00+0 TDVZIJ -(r'I) T00+60VHJ*T og=(f) Q

Sovxd=(r)o€oex3=(r)H90'x3=(f)V

.Sv'Ir'€=rT€ZOQ93Vxi4(r'ZI)T00+OT0v1d (f'I)Too+60VHJ*TO9=(Z)a

ZaVxd-=(Z)09T0vId=(Z)a

0'0=(Z)HT+I=ZI

z=rZ=I

.IOI'IdwI'' ''A UNVZIOIZdXa'' ' ''X

0

Z9i

6T 0Vxdr(f'I) TOO+60Vx3T(f'T I) T00=(f) QSOvx3=(f)0€oexj=(f)S90Hx3=(f)V

ZSV'If' €=fT SZ OQ6T3Vxdr(f'I)T00+60Hx.;=(f'TI)T00=(Z)Q

ZOV&I-=(Z) 09TOVHJ=(Z)a

o'0=(Z)HT-I=TIXvwI=I

TINNOO017Z(da.S)vOa 'I'IHO

Page 175: Optimal Design and Operation of Wastewater Treatment Plants by

251 CONTINUEA(JAST1)=-FRAC2B(JAST1)=FRACY1C(JAST1)=0 .0D(JAST1)=CO1(I1,JAST1)•FRAC9+CO1(I,JAST1)*FRAC19CA TDA(STEP)DO 242 I=2,IMAXC1(I,1)=C1(I,3)+C1(I,2)*FRAC88

242

C1(I,JMAX)=C1(I,JAST)-FRACY3*C1(I,JAST1)DO 285 I=2,IMAXDO 285 J=1,JMAXC01(I,J)=C1(I,J)C01(1,J)=BC1

285 CONTINUEDO 611 J=1,JMAXI=ASTCO1(IMAX,J)=C1(I,J)

611 CONTINUEGO TO 218

C

THE FOOWING SEGMENT IS EXECUTED FOR THE EVEN VAUES OF K .300

STEP=2 .0C

XIMPICIT AND YEXPICITJ=2I=2J2=J+1A(2)=0 .0B(2)=FRAC12C(2)=-FRAC78D(2)=CO1(I,J)*FRAC17+C01(I,J2)`FRAC2+BC1*FRAC9DO 254 I=3,ASTA(I)=-FRAC9B(I)=FRAC12C(I)=-FRAC78D(I)=CO1(I,J)*FRAC17+CO1(I,J2)*FRAC2

254 CONTINUEA(IMAX)=-FRAC9B(IMAX)=FRAC20C(IMAX)=O .0D(IMAX)=CO1(IMAX,J)*FRAC17+CO1(IMAX,J2)*FRAC2CA TDA(STEP)DO 260 J=3,JASTJ1=J-1J2=J+1

C

INET BOUNDARY CONDITIONA(2)=0 .0B(2)=FRAC12C(2)=-FRAC78I=2D(2)=CO1(I,J1)*(-FRAC6)+C01(I,J)*FRAC31+C01(I,J2)*(-FRAC5)1+BC1*FRAC9

C

THE INTERIOR GRIDDO 270 I=3,ASTA(I)=-FRAC9

1 63

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B(I)=FRAC12C(I)=-FRAC78D(I)=CO1(I,J1)*(-FRAC6)+CO1(I,J)*1FRAC31+CO1(I,J2)*(-FRAC5)

270 CONTINUEC

THE EXTERIOR BOUNDARY CONDITIONA(IMAX)=-FRAC9B(IMAX)=FRAC20C(IMAX)=0 .0D(IMAX)=CO1(IMAX,J1)*(-FRAC6)+CO1(IMAX,J)*FRAC31+CO1(IMAX,J2)*1(-FRAC5)CA TDA(STEP)

260 CONTINUEJ=JAST1J1=J-1I=2A(2)=0 .0B(2)=FRAC12C(2)=-FRAC78D(2)=BC1*FRAC9+C01(I,J1)*FRAC2+CO1(I,J)*FRAC18DO 255 I=3,ASTA(I)=-FRAC9B(I)=FRAC12C(I)=-FRAC78D(I)=CO1(I,J1) , . FRAC2+C01(I,J)*FRAC18

255 CONTINUEA(IMAX)=-FRAC9B(IMAX)=FRAC20C(IMAX)=O .OD(IMAX)=C01(IMAX,J1)*FRAC2+CO1(IMAX,J)*FRAC18CA TDA(STEP)DO 262 I=2,IMAXC1(I,1)=C1(I,3)+FRAC88*C1(I,2)

262

C1(I,JMAX)=C1(I,JAST)-FRACY3*C1(I,JAST1)DO 263 I=2,IMAXCO1(I,1)=C1(I,1)

263

C01(I,JMAX)=C1(I,JMAX)DO 295 I=2,IMAXDO 295 J=1,JMAXCO1(I,J)=C1(I,J)C01(1,J)=BC1

295 CONTINUEDO 612 J=1,JMAXI=ASTC01(IMAX,J)=C1(I,J)

612 CONTINUECC

CACUATION OF THE EFFUENT CONCENTRATION FROM THE PRIMARYC

SEDIMENTATION TANKC

DO 305 J=20,JMAXECONC1=0 .0DO 310 I=3,IMAX

1 64

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ECONC1=ECONC1+C01(I,J)310 CONTINUE

ECONC2(J)=ECONCI/IMAX1ECONC3=ECONC3+ECONC2(J)

305 CONTINUEECONC4=ECONC3/JMAX1ECONC5=((SSIN-ECONC4)/SSIN)y100 .

CC

CACUATION OF SUDGE CONCENTRATION, DRY SUDGE MASS(IN GRAM)C

AND VOUME OF SUDGE(IN CUBIC METER) IN THE BOTTOM OF THEC

PRIMARY SEDIMENTATION TANKC

DO 320 J=1,3SCONC1=0 .0DO 330 I=3,IMAXSCONC1=SCONC1+C01(I,J)

330 CONTINUESCONC2(J)=SCONCI/IMAX2SCONC3=SCONC3+SCONC2(J)

320 CONTINUESCONC4=SCONC3/3 .DMASS=SCONC4*XMAX- 3 . *DZ-`WIDTH `CFACTISVO=(DMASS/(DENSTY-`PSDGE))*CFACT1

218 TIME=TIME+DTIF(TIME .E .3599 .) GO TO 220IF(TIME .EQ .3600 .) TIME1=1 .0H1(II)=HEIGHTSSIN1(II)=SSINQ1(11)=QXMAX1(II)=XMAXHVE1(II)=HVEECONC6(II)=ECONC5ECONC7(II)=ECONC4WIDTH1(II)=WIDTHEX1(II)=EXOVE1(II)=OVEII=II+1112=II-1ETIME=ETIME+TIME1Q=QAV`FOW(ETIME)SSIN=TSSAV*TSS(ETIME)PRINTI=PRINTI+TIME

C

CA PRINTA(CO1,IMAX,JMAX,PRINTI,DX)C

WRITE(6,1190) ECONC4C1190 FORMAT(////2X,'EFFUENT CONCENTRATION OF THE PSD'C

1' TANK IN MG/=',FlO .5)C

WRITE(6,1200) SCONC4C1200 FORMAT(/2X,'SUDGE CONCENTRATION IN THE PSD',C

1' TANK IN MG/=',F10 .5)C

WRITE(6,1210) DMASSC1210 FORMAT(/2X,'DRY MASS OF SUDGE IN THE PSD',C

1' TANK IN GRAM=',E13 .5)C

WRITE(6,1220) SVO

16 5

Page 178: Optimal Design and Operation of Wastewater Treatment Plants by

C1220 FORMAT(/2X,'SUDGE VOUME IN THE PSD TANK IN',C

1' CUBIC METER=',E13 .5)TIME=0 .0

220 CONTINUEIF(ETIME .T .20 .) GO TO 777DO 681 I=1,IMAXWRITE(26,6662) (C01(I,J),J=1,JMAX)

6662 FORMAT(10E13 .5)681 CONTINUE

DO 666 I=1,II2WRITE(6,2221) Q1(I),SSIN1(I),H1(I),XMAX1(I),HVE1(I),EX1(I),1OVE1(I),ECONC7(I),ECONC6(I)

2221 FORMAT(/2X,9(1X,F10 .3))666 CONTINUE

DO 671 I=1,II2WRITE(26,2222) Q1(I),SSIN1(I),H1(I),XMAX1(I),HVE1(I),EX1(I),1OVE1(I),ECONC7(I),ECONC6(I)

2222 FORMAT(2X,9(2X,F10 .3))671

CONTINUEDHT=100 .HEIGHT=HEIGHT+DHTIF(HEIGHT .T .400 .) GO TO 123STOPEND

CCC

SUBROUTINE TDA(STEP)C

TRIDIAGONA AGORITHM . THIS SUBROUTINE IMPEMENTS THE TRIDIAGONAC

AGORITHM .COMMON AST,I,J,KPUS1,C1(51,51),A(60),B(60),C(60),D(60)DIMENSION BETA(100),GAMMA(100)BETA(2)=B(2)GAMMA(2)=l)(2)/B(2)AST1=AST+1AST2=AST-1IF(STEP .GT .1 .5) GO TO 12DO 10 I1=3,ASTIESS1=I1-1BETA(I1)=B(I1)-(A(I1)*C(IESS1)/BETA(IESS1))GAMMA(I1)=(D(I1)-A(I1)*GAMMA(IESSI))/BETA(I1)

10

CONTINUEGO TO 14

12

DO 11 12=3,AST1IESS2=I2-1BETA(12)=B(I2)-(A(I2)*C(IESS2)/BETA(IESS2))GAMMA(I2)=(D(I2)-A(I2)*GAMMA(IESS2))/BETA(I2)

11

CONTINUE14

IF(STEP .GT .1 .5) C1(AST1,J)=GAMMA(AST1)IF(STEP .E .1 .5) C1(I,AST)=GAMMA(AST)IF(STEP .E .1' .5) GO TO 2DO 30 K4=1,AST2I3=AST1-K4

166

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IPUS2=I3+1C1(13,J)=GAMtIA(I3)-(C(I3)*Cl(IPUS2,J)/BETA(I3))

30

CONTINUEGO TO 40

2

DO 20 K3=2,AST214=AST1-K3IPUS1=I4+1C1(I,I4)=GAMMA(I4)-(C(I4)*C1(I,IPUS1)/BETA(I4))

20

CONTINUE40

RETURNEND

CCCC

SUBROUTINE PRINTA(ARRAY,IMAX,JMAX,PRINTI,DETX)DIMENSION ARRAY(IMAX,JMAX)DATA ICOUNT/1/NJ=6WRITE(NJ,1010) PRINTI,ICOUNT

1010 FORMAT(////10X,'

TIME=',F12 .1,1OX,' PRINT NO=',I3)WRITE(NJ,1020)

1020 FORMAT(/50X,'

DEPTH')ICOUNT=ICOUNT+1CACUATE THE SPACING FOR PRINTING=JMAX/10WRITE(NJ,1030)(J,J=1,JMAX,)

1030 FORMAT(/11(4X,I3,4X))DO 10 I=1,IMAXWRITE(NJ,1040) (ARRAY(I,J), J=1,JMAX,)

1040 FORMAT('0',11F11 .5)10

CONTINUERETURNEND

CCC

FUNCTION TSS(TIME)DIMENSION A(5),B(5),C(5)DATA A/0 .0,-6 .96097E-02,- .176173, .14660,-9 .67005E-02/,1B/0 .0,2 .60089E-02,- .274343,4 .09673E-02,2 .49002E-02/,2C/l .,2 .,7 .,14 .,21 ./,F/3 .73999E-02/TSS=1 .0DO 10 I=1,5THETA=F*C(I)*TIME

10

TSS=TSS+A(I)*COS(THETA)+B(I)*SIN(THETA)RETURNEND

CFUNCTION FOW (TIME)DIMENSION A(5),B(5),C(5)DATA A/0 .0,5 .41989E-02,- .036769,- .052324, .0618556/,B/0 .0,

1 - 1 .3742E -03,2 .57417E-02,- .201479, .155797/,C/1 .,2 .,5 .,7 .,14 ./,

167

Page 180: Optimal Design and Operation of Wastewater Treatment Plants by

2F/ .0373999/FOW=1 .0DO 10 I=1,5THETA=F*TIRE*C (I)

10

FOW=FOW+A(I)*COS(THETA)+B(I)*SIN(THETA)RETURNEND

168

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CCCC

DYNAMIC MODE OF ANAEROBIC DIGESTIONCC

DEVEOPED BY PRASANTA K .BHUNIACCCMACRO XBDJ,XPTJ,XBTJ,XSJ,XH2J,XMJ,BDJ,SJ,PTJ,NTJ,HTJ,H2J,DHTJ, . . .THJ,DPTJ,DNTJ,BDOJ,NBDOJ,XNVOJ,XNCDJ,BTOJ,SPJ,PPJ,NTPJ,HTPJ,DH2J, . . .BNJ=DT1(XPI,XBI,XSI,XH2I,XMI,SI,BSI,PTI,NTI,HTI,H2I,MA,MP,MB,MM,DTHJ, . . .MH,MU,MBD,VD,XAR,XPR,XSR,XIR,X2R,XNR,XIR,PCC,QII,CII,PCI,XNCDI,BNDI,SRT)

ANAEROBIC DIGESTER‚

FOW IS IN M-13/HR, VOUME IS IN M**3_I.

MASS BAANCES ON THE MICROBIA CONCENTRATIONS OF PROPIONIC ACID,‚

N-BUTYRIC ACID,ACETIC ACID, H2 AND METHANE FORMERSMSSR1=XAR+XPR+XSR+XIR+X2RMSSR2=MSSR1+XIR+PCC+XNRBDOJ=C11*((MSSRI+CONBD*PCC)/MSSR2)NBDOJ=C11*((XIR+CONNB*PCC)/MSSR2)XNVOJ=C11*((XNR+CONNV*PCC)/MSSR2)VD=SRT*QII*24 .

INVERSE OF RETENTION TIME (1/HOURS)THJ=QII/VD

BIODEGRADABE SOIDS HYDROYZERSDXBDJ=THJ*(0 .0-XBDJ)+(MBD-KDBD)*XBDJXBDJ=INTGR(XBDI,DXBDJ)

PROPIONIC ACID OXIDIZERSDXPTJ=THJ*(0 .O-XPTJ)+(MP-KDP)*XPTJXPTJ=INTGR(XPI,DXPTJ)

N-BUTYRIC ACID OXIDIZERSDXBTJ=THJI. (O .O-XBTJ)+(MB-KDB)*XBTJXBTJ=INTGR(XBI, DXBTJ)

SOUBE SUBSTRATE OXIDIZERSDXSJ=THJ*(0 .O-XSJ)+(MU-KDS)*XSJXSJ=INTGR(XSI,DXSJ)

HYDROGEN CONSUMERSDXH2J=THJ*(0 .O-XH2J)+(MH-KDH2)*XH2JXH2J=INTGR(XH2I,DXH2J)

METHANE FORMERSDXMJ=THJ*(0 .0-XMJ)+(MM-KDM)*XMJXMJ=INTGR(XMI,DXMJ)

a

BIODEGRADABE SOIDS MASS BAANCE

1 69

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.4

RXN1=MBD*XBDJ/YXSODBDJ=THJ*(BDOJ-BDJ)-RXN1BTOJ=BDOJ*QIIBDJ=INTGR(BSI,DBDJ)

NON-BIODEGRADABE SOIDS MASS BAANCEDBN=THJ*(NBDOJ-BNJ)BNJ=INTGR(BNDI,DBN)

NON-VOATIE SOIDS MASS BAANCEDXNCD=THJ`(XNVOJ-XNCDJ)XNCDJ=INTGR(XNCDI, DXNCD)

SOUBE ORGANICS MASS BAANCERXN2=MU*XSJ/YXSTMYXSC=(l .-YXSO-YCO21)RXN11=TMYXSC*RXN1DSJ=THJ*(0 .O-SJ)-RXN2+RXN11S PJ=RXN 11*VDSJ=INTGR(SI,DSJ)

PROPIONIC ACID MASS BAANCERXN4=MP*XPTJ/YXPACRXN21=RXN2` (1 .-YXS-YCO22)PPJ=(RXN21*YPACS)*VDDPTJ=THJ*(PTIN-PTJ)-RXN4+RXN21*YPACSPTJ=INTGR(PTI,DPTJ)

N-BUTYRIC ACID MASS BAANCERXN5=MB*XBTJ/YXNBACNTPJ=(RXN21*YNBACS)*VDDNTJ=THJ*(NTIN-NTJ)-RXN5+RXN21*YNBACSNTJ=INTGR(NTI,DNTJ)

ACETIC ACID MASS BAANCERXN6=MM*XMJ/YXARXN41=RXN4* (1 .-YXPAC)RXN51=RXN5*(1 .-YXNBAC)HTPJ=(RXN41*YAP+RXN51 YANB+RXN21*YHCS)*VDDHTJ=THJ*(HTIN-HTJ)-RXN6+RXN41*YAP+RXN51*YANB+RXN21*YHCSHTJ=INTGR(HTI,DHTJ)

MASS BAANCE FOR H2RXN7=MH*XH2J/YXH2DH2J=THJ*(H2N-H2J)-RXN7+RXN41*YHP+RXN51*YHNB+RXN21*YH2S+DTHJH2J=INTGR(H2I,DH2J)

ENDMACROMACRO CMJ,CTJ,QCJ,Q4J,PCJ,CAJ,CPJ,CBJ,CCJ,CAMJ,HC03J,HAJ,PAJ, . . .NBAJ,HOJ,C2J,QJ,BDCJ,Q4MJ,Q4HJ,PHJ,QH2J,TH2J,DTHJ=DT2(PCI,CTI, . . .N4N,C2N,HC03IN,VD,QII,CMI,CAI,CAMI,XMJ,XH2J,XSJ,MM,MU,MH,MBD,ZI, . . .CPI,CCI,HTJ,PTJ,NTJ,DHTJ,DPTJ,XBDJ,BDCI,DNTJ,TP,H2J,PHI,THI ,CBI)y

CARBONATE AND AMMONIA SYSTEM AND PH RATE OF C02 FORMATION

170

Page 183: Optimal Design and Operation of Wastewater Treatment Plants by

*C02 PRODUCTION FROM BIOOGICA SOIDS AND SOUBE SUBSTRATESDBDCJ=(MBD*XBDJ/YXSO)*YC021+(MU*XSJ/YXS)-YCO22BDCJ=INTGR(BDCI,DBDCJ)

C02S=KHC02*PCJ*44 .E+03‚

RATE OF GAS TRANSFER TO GASEOUS PHASE,GRAMS/M**3 .HRDCTJ=KA*(C02S-C2J)CTJ=INTGR(CTI,DCTJ)H2S=KHH2*PHJ*MH2*1 .E+03DTHJ=KA1*(H2S-H2J)TH2J=INTGR(THI,DTHJ)

TOTA FOW OF C02 AND CH4 IN M**3/HRQCJ=-D*DCTJ*VD-• .02272E-03Q4MJ=(MM*XMJ*YCH4X/XMW)*D*VD*1 .E-03Q4HJ=((MH*XH2J/YXH2)*YMH/CH4M)*D*VD*1 .E-03Q4J=Q4MJ+Q4HJQH2J=-DTHJ..VD*D*1 .E-03/MH2QJ=Q4J+QCJ+QH2JDPCJ=-TP*;D*(VD/VG)-`DCTJ* .02272E-03-(PCJ/VG)*QJPCJ=INTGR(PCI,DPCJ)DPHJ=-TP*D*(VD/VG)•DTHJ*1 .E-03/MH2-(PHJ/VG)*QJPHJ=INTGR(PHI,DPHJ)

*

RATE OF C02 PRODUCTION FROM HC03- BY PROPIONIC ACID FORMATIONDCPJ=DPTJCPJ=INTGR(CPI,DCPJ)

RATE OF C02 PRODUCTION FROM HC03- N-BUTYRIC ACID FORMATIONDCBJ=DNTJCBJ=INTGR(CBI,DCBJ)

RATE OF C02 PRODUCTION FROM HC03- BY CATION FORMATIONDZJ=((QII/VD)*(ZI-CCJ))DCCJ=DZJCCJ=INTGR(CCI,DCCJ)

4-r.

.4BY METHANE FORMATION,GRAMS/M',.*3 .HR

VG=PVG*VDDCMJ=MM*XMJ*YC02X*44 ./XMWCMJ=INTGR(CMI,DCMJ)

RATE OF C02 PRODUCTION FROM HC03- BY ACETIC ACID FORMATIONDCAJ=DHTJCAJ=INTGR(CAI,DCAJ)

RATE OF C02 FORMATION BY AMMONIADNH4J=(QII/VD)*(N4N-CAMJ)+MU*XSJ*YNH4DCAMJ=DNH4JCAMJ=INTGR(CAMI,DCAMJ)

DHC03J=DZJ+DNH4J-DPTJ-DNTJ-DHTJHC03J=INTGR(HC03I,DHC03J)AH1=KC02*C2J/HC03J

1 71

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K1=AH1/KHAJ=HTJ*K1PAJ=PTJ*K1NBAJ=NTJ*KlHOJ=HC03J+HAJ+PAJ+NBAJDHC31J=(QII/VD)*(HC03IN-HOJ)DC21J=(QII/VD)*(C2N-C2J)DC2J=DC21J+DCMJ+DCTJ+DCAJ+DCPJ+DCBJ-DCCJ+DNH4J+DHC31J+DBDCJC2J=INTGR(C2I,DC2J)

ENDMACROINITIA

PARAM XAR=8637 .,XPR=5443 .,XSR=1161 .,X1R=25 .8,X2R= .I,XNR=10880 .PARAM XIR=17515 .,PCC=5500 .,C11=43662 .PARAM QII=41 .617,MU= .01667,YXSO=0 .08,YXS= .05PARAM MBD=0 .0125,KDBD=0 .0001,XBDI=1615 .3,KSBD=3000 .PARAM YHCS=0 .235,YPACS=0 .36,YNBACS=0 .386,YH2S=0 .01PARAM MP= .018,MB= .02,MA= .01625,MH= .045,MM= .016667PARAM YXA= .0466,YXPAC= .02,YXNBAC= .02,YHP= .08099,YHNB= .0454PARAM YAP=0 .8106,YANB=1 .363,YXH2=1 .05,KDP= .00001,KDB= .00001PARAM KDS= .00001,KDH2= .00001,KDM= .00001,K1P=45 .,K1B=45 .PARAM K1A=39 .,KSP=2 .,KSB=2 .,KSA=2 .,KH2=1 .,YC02X=47 .,YMH=2 .PARAM XMW=113 .,KHC02=3 .23E-05,KA= .41667,D=25 .7,CH4M=16 .PARAM SRT=5 .,TP=730 .,YC021=0 .05,BDCI=O .O,YC022=0 .05PARAM YNH4=0 .1212,K=1 .4725E-05PARAM FDM=3204 .2,KC02=1 .E-06,YCH4X=47 .,H2N=0 .PARAM XNCDI=3292 .,XPI=146 .,XBI=146 .,XSI=145 .,XH21=469 .,XMI=269 .PARAM BSI=337 .,SI=17 .,PTI=23 .0,NTI=21 .,HTI=24 .PARAM H21=0 .2,CTI=-7041 .,PCI=290 .,CMI=4128 .,HC03IN=O .,HC03I=4016 .PARAM CAI=10 .0,CPI=14 .,CBI=11 .3,CCI=50 .PARAM NH4I=5 .0,C2N=0 .,BNDI=9100 .,ZI=50 .0,CAMI=129 .,C2I=456 .PARAM N4N=30 .0,KN=O .O,KS=150 .,KTA=5 .PARAM QCH4I=O .O,QC02I=O .O,TOTQI=0 .0PARAM CONBD=0 .7,CONNB=0 .3,CONNV=0 .35PARAM PTIN=O .O,NTIN=O .O,HTIN=0 .0,KA1=0 .416667PARAM CONVF1=16018 .7,CONVF2=35 .3147,CB1=453 .6,KSI=2580 .PARAM BTI=O .,SRPI=O .,PTRI=O .,NTRI=O .,HTRI=0 .,Q4MI=0 .0PARAM Q4HI=0 .0,PVG=0 .1,EPS1=0 .00003,EPS2=0 .00003,BDII1=300 .PARAM XBDII1=1500 .,MH2=2 .,PHI= .2,THI= .05,KHH2= .9E-06,KH2I=2 .

FN=0 .0*DYNAMICPROCEDURE DIFF1,BDII2,DIFF2,XBDII2=CHECK(EPS1,EPS2)

END PROCEDURE*

1 72

IF(KEEP-1) 306,310,310310 BDII2=BD1

XBDII2=XBD1DIFF1=ABS(BDII2-BDII1)DIFF2=ABS(XBDII2-XBDII1)IF((DIFFI .T .EPS1) .AND .(D IFF2 .T .EPS2)) FN=1 .0

306

BDII1=BDII2XBDII1=XBDII2CONTINUE

Page 185: Optimal Design and Operation of Wastewater Treatment Plants by

XBD1,XPT1,XBT1,XS1,XH21,XM1,BD1,S1,PT1,NT1,HT1,H21,DHT1, . . .TH1,DPT1,DNT1,BDOI,NBDO1,XNVO1,XNCD1,BTO1,SP1,PP1,NTP1,HTP1,DH21, . . .BN1=DT1(XPI,XBI,XSI,XH2I,XMI,SI,BSI,PTI,NTI,HTI,H2I,M1,M2,M3,M4,DTH1, . . .M5,M6,M7,VD,XAR,XPR,XSR,XIR,X2R,XNR,XIR,PCC,QII,CII,PCI,XNCDI,BNDI,SRT)CM1,CT1,QC1,Q41,PC1,CA1,CP1,CB1,CC1,CAM1,HC031,HA1,PA1, . . .NBA1,HO1,C21,Q1,BDC1,Q4M1,Q4H1,PH1,QH21,TH21,DTH1=DT2(PCI,CTI, . . .N4N,C2N,HC03IN,VD,QII,CMI,CAI,CAMI,XM1,XH21,XS1,M4,M6,M5,M7,ZI, . . .CPI,CCI,HT1,PT1,NTI,DHT1,DPT1,XBD1,BDCI,DNT1,TP,H21,PHI,THI,CBI)

TACID=PT1+NT1+HT1VBNBI=NBD01-XNVO1VSSIN=BDOI+VBNBIVBNBO=BN1-XNCD1VSSO=BD1+VBNBO

-

OF VSS DESTROYEDPVSSD=(VSSIN-VSSO)/VSSIN

.

a

y

RATE OF VSS DESTROYED IN B VSS/HRRVSSD=QII*(VSSIN-VSSO)/CB1

OR : ORGANIC OADING RATE IN GRAMS/M *3 DAYOR1 : ORGANIC OADING RATE IN B/FT *3 DAYOR=VSSIN*QII*24 ./VDOR1=OR/CONVF1

GPRDAP : GAS PRODUCTION / VSS APPIED IN FT**3/B VSS APPIED‚

GPRDRD : GAS PRODUCTION/ VSS DESTROYED IN FT**3/B VSS DESTROYEDGPRDAP=(Q1*CB1/(QII*VSSIN))*CONVF2GPRDRD=(Q1/RVSSD)*CONVF2BDT1=INTGR(BTI,BTO1)SRP1=INTGR(SRPI,SP1)PTR1=INTGR(PTRI,PP1)NTRI=INTGR(NTRI,NTPl)HTR1=INTGR(HTRI,HTP1)Q4MT=INTGR(Q4MI,Q4M1)Q4HT=INTGR(Q4HI,Q4H1)QCH4=INTGR(QCH4I,Q41)QC02=INTGR(QC02I,QC1)TOTQ=INTGR(TOTQI,Q1)PQCH4=TP-PC1-PH1PRC02=PC1/TPPRCH4=PQCH4/TP

INCORPORATION OF INHIBITION FUNCTION BY THE UNIONIZED ACIDS‚

IN THE SPECIFIC GROWTH RATE OF PROPIONIC,N-BUTYRIC,ACETIC ACID,HYDROGEN, AND METHANE FORMERS RESPECTIVEY .DMU=PA1/K1P+NBA1/K1B+HA1/K1ATA1=PA1+NBA1+HA1DMU1=1 .+KS/S1+TACID/KSIDMP=1 .+KSP/PA1+DMU+H21/KH2IM2=MP/DMPM6=MU/DMU1DMB=1 .+KSB/NBA1+DMU+H21/KH2I

173

Page 186: Optimal Design and Operation of Wastewater Treatment Plants by

VY

IZHN/TZH+nN(I+TvgN/HSN+' T=arclI lNQ/flW=9WdNQ/dW=ZN

IZH)I/TZH+f1WQ+TVd/dSN+' T=dNGIS)I/QIOV+TS/SX+' T=Tf1NG

THH+TV N+tIId=TVYTX/TVH+gT)I/TVHN+dTN/TVd=f1WQ

A'ISAI.OSdSSH SHSW IOd SNVH.HW (INV `NHJOHQAH`QIOV OI.HOV`OIHflg-N`OINOIdOHd JO H1:VH HIMOHJ OIdIOSdS SH, NI

SQIOV QHZINOINfl SI Ag NOONI1d NOIgIHNI JO NOIS.VHOdHOONI

TTTT

OgNHA+TQH=OSSAIQONX-TNg=OHNgA

IaNgA+TOGA=NISSATOANX-TOQHN=IHNHATZH+N+T.d=G I OVI

(IgO`IHI' IHd`TZH`d.`TZNG'I3Ga'IGHX`T.dG`HG'T.N`Tld`TZH`IOO`Id3''"IZ`N'gN'9W`'7NcTSX`TZHX`TWX`INVD'IVO`IWO`IIb`aA`NI€OOH`NZO`Nt,N"'`O`IOd)za=TH.Q`TZH.`TZHb`THd`TH+7b`TW+Ib`TOQg`Tb`TZO`TOH`TvaN

`TVd`TVH`T €OOH`TWVD' 100' T gO`TdD' TVO`T Od`T+7b`T Ob`T.D' TWO(,HS`IQNH`IQONX`IOd`TTO`IIb`OOd`HIX`HNX`HZX`HTX`HSX`HdX`HVX`QA`W`9W`SW""TH.(I`+7N'CN'ZN'tN'IZH`I.H`IZN`IZd`ISg`IS`IWX`IZHX`ISX`IHX`IdX)T.Q=TNg

"'`TZHQ`TdH`IdN`tdd`TdS`TO.g`TQONX`TOANX`IOQgN`TOQa`T.Na'IIdG'IHZ"'`T.HQ`TZH`UH`TS.N`T,d`TS`TQH`TWX`TZHX`TSX`IJ X`dX`TQHX

d1./+7HObd=+7HOHdd./TOd=ZOOHd

THd-TOd-d.=+7HObd(T b`Ib'OS.)'IHJ.NI=b'OZ(T Ob`I Z0Ob)'IHJ,N I=ZOOb(T+7b'I+7HOb)'IHJ.NI=+7HOb(TH+7b`IH+7b)'IHJ.NI=lH+7b(TW+7b` IW'7b)'IHJS.NI=JW+7b(Td,H`IH.H)ZHJI.NI=TlH(T d,N`IH,N)'IHJ.NI=T HZN(T d d`I H.d) ZHJ.N I=T H.d(T dS` IdHS)'IHJ,NI=T dHS(T Osg`H)'IHO.NI=T1.Qg

ZJANOO;:((ISSAH/Tb)=QHQHdJZdANOO;:((NISSAMMIIb) /Ta'IO;:Tb)=dV HdJ

QHiOH,SSQ SSA H I/€m;‚,d NI QHAOH,SSQ SSA /NOOIIQOHd SVJ:QJpJJ3QHI'IddV SSA

NI GHI'IddV SSA / NOIS.OfKIOHd SvJ:dV(IHdD

T JANOO /H'IO=T H'IOGA/'17Z,,I Ib;:NI SSA=H'IO

AVG €;:,-.3/HI NI H.VH JNIGVO'I OINVfJIO:TH'IOAVG €;:;:W/SWVHJ NI HZHH JNIGV0'I OINVOHO:H'IO

TH'IO/(OSSA-NISSA);:IIb=GSSAHHH/SSA TI NI QSAOHZSHQ SSA JO S.HH;:

NISSA/(OSSA-NISSA)=GSSAdQSAOH.SSQ SSA JO %;-

Page 187: Optimal Design and Operation of Wastewater Treatment Plants by

M3=MB/DMBDMA=1 .+KSA/HA1+DMUM1=MA/DMADMH2=1 .+KH2/H21+DMUM5=MH/DMH2DMM=1 .+KTA/TA1+DMUM4=MM/DMMM7=MBD/(1 .+(KSBD/BD1))

%~

HYDROGEN ION CONCENTRATION CACUATED BY THE CARBONATE EQUIIBRIAKC02=AOG10(KC02)C02=AOG10(C21)HC03=AOG10(HCO31)H=KC02+C02-HCO3PH=-H

NOSORTCA DEBUG(1,250 .)

TERMINATHETAD=VD/QII

.t.

y

CONSTRAINT ON THE MAXIMUM PERMISSIBE OADING RATEFD=BD1VD 1=Q I I :;THETADVD2=FD-`QII/FDMVD3=AMAX1(VD1,VD2)

METHOD MINETIMER FINTIM=1 .,DET= .01,PRDE=1 .0,OUTDE=1 .0,DEMIN=0 .25E-10FINISH FN=1 .0PRINT XBD1,XPT1,XBT1,XS1,XH21,XM1,BD1,S1,PT1,NT1,HT1,H21, . . .CM1,CT1,QC1,Q41,PC1,CA1,CP1,CB1,CC1,CAM1,HCO31,HO1,HA1,PA1,NBA1, . .C21,BN1,XNCDI,QCH4,QC02,PQCH4,PRC02,PRCH4,PH,PVSSD,OR,OR1, . . .BDT1,SRP1,PTR1,NTR1,HTR1,Q4MT,Q4HT,TOTQ,GPRDAP,GPRDRDOUTPUT QH21,TH21,PH1OUTPUT TACID,PT1,NT1,HT1,PRCH4OUTPUT PRC02,PH,HC031,X1OUTPUT QCH4,QC02,M4,M7OUTPUT HA1,PA1,NBA1,PHOUTPUT M1,M2,M3,M5,M6ENDPARAM SRT=20 .,BDII1=300 .TIMER FINTIM=1 . DET= .O1,PRDE=1 .0,OUTDE=1 .0,DEMIN=0 .25E-10ENDPARAM SRT=15 .,BDII1=300 .TIMER FINTIM=1 .,DET=.01,PRDE=1 .O,OUTDE=1 .0,DEMIN=0 .25E-10ENDPARAM SRT=12 .,BDII1=300 .TIMER FINTIM=1 .,DET= .O1,PRDE=1 .0,OUTDE=1 .0,DEMIN=0 .25E-10ENDPARAM SRT=10 .,BDII1=300 .TIMER FINTIM=1 .,DET= .01,PRDE=1 .0,OUTDE=I .O,DEMIN=0 .25E-10ENDPARAM SRT=8 .,BDII1=300 .

17.5

Page 188: Optimal Design and Operation of Wastewater Treatment Plants by

TIMER FINTIM=I .,DET= .0I,PRDE=I .O,OUTDE=I .O,DEMIN=0 .25E-10ENDPARAM SRT=5 .,BDII1=300 .TIMER FINTIM=1 .,DET= .0I,PRDE=I .O,OUTDE=I .O,DEMIN=0 .25E-10ENDSTOPENDJOB

176

Page 189: Optimal Design and Operation of Wastewater Treatment Plants by

I

(rvxa `rIvX)'IHO,NI=rvXJM+(fA/(fVX fJ.b-fM*fzHb+fOVX*fTb))=fVXa

VXa)I-IdVX2I=dVXH(ZHSH+TvXH)*TA=TdVXH

fVXa=aX=HXGNT

ssv,w 3AIioeT

(rsxa`risx)'HO.NI=fSXTM-dSXH+(fA/(fsX*f,b-rxsx;=fzHb+rosX-,=rTb) )=rsxa

TA/rsa,-rvx,-vXH=TvxHAHdXH+THSH=dSXH

SSVNUHHO.S

,~

(fdXa `f IdX)'IHOZNI=rdXAHdXH- (rA/ (fdX:,:r.b-rHdX*fZHb+rodxrrib) )=fdXa

€A,=( (fda+ds)I) /fda);fVX. HH=AHdXH

H.V SgfS HIWIfOHVd aHHO,S

(rsa`rIS)'IHOZNI=rsZESH-THSH- (fA/ (rS*f,b-fHS*fZHb+ros:,:rib))=fsa

rs*fvx-."SH=zHSH(fsa-HS3)-,-rs4rvx= Jx=THSH

aoNH'IvgSSHWHZVHSgfS H'Ign'IOS a'Igvavaoaaorg

~:

(fix-rzx) /fdx=fda(fix-fax-r.x) /rsx=fsa(fax+r Ix+rex+rsx)=r,x

rib+rzNb=rs.bT

`MO'IM HOVHHAV = Wb

r€, -W`)INV. NOIIVHHV aH.JOawn'IOA = A

T

WZSAS snOaDVNOgHeo

;:T

(rxa`rIa`roa`fHNx`fINX`fONX`fozx`frzx`rITX`foTX'fI€N`fIZN`fI'7N`fIIX'fIvx‚‚`r~xo`rrax`rrsx`rrs`rzxx`rTHx`r€NH`rzNH`r~NH`ro€N`rozN`ro~N`rHlx`rH~x

‚‚`rxax`rosx`rHSx`rxs`rorx`roux`roax`ros`rzxb`rTb)a~=rzN`r€N`r~N‚

‚‚`rNO`rHo`rNX`ra`rzx`fix`rA`r,x`rdx`fIX`fVX'fSX'fS'f.b oHOvwT

(sioOvar Moud On'Id)HO.OVHH aWn'IOA OHHZ ONIMISNOO NOIZWInNIS HOQAZS ai.HAIZDV

VINfHg‚xVINVSVad Ag a1ZVHH0SIWFIHOOHd SINH SAS ,NHWZVa V JO~:

SHH,HWVHVd ONVHHdO cNv NOISHa 'IVWIZdO aNIdOZaaSnSI

,tHInaa3OHd NOIIVZINdo HZIM GHIdn00MOMHOanIS aHZVAIZOV

(€)HOIHM`(€)dHH`(ii)WO`(Ti)ZS000I

/`(S)nHvd`(S)'IHvd`(S)a'IOHVd`(TT`S`€)dNIO`(€`iT)HH NOISNHNIG

/

Page 190: Optimal Design and Operation of Wastewater Treatment Plants by

*

*

*

.t .

INERT MASS*

***

RXIF=Y2*KDXADXIJ=((Q1J*XIOJ+QR2J*XIRJ-QTJ*XIJ)/VJ)+RXIFXIJ=INTGR(XIIJ,DXIJ)

NON-VOATIE SOIDS

DXNJ=((Q1J*XNOJ+QR2J*XNRJ-QTJ*XNJ)/VJ)XNJ=INTGR(XNIJ,DXNJ)

*‚

NITROGENEOUS SYSTEM‚

AMMONIA NITROGEN BY NITROSOMONAS.

MUNS=MUHNS*(N4J/(KSNS+N4J))MUNS1=MUNS*X1J/YNSRHNH4=(-Y1*(RXA1+RSR2)+Y2P*KDXA)*KNDN4J=((Q1J*N40J+QR2J*RN4J-QTJ*N4J)/VJ)-MUNS1+RHNH4N4J=INTGR(N4IJ,DN4J)

NITRITE NITROGEN BY NITROBACTER

MUNB=MUHNB*(N2J/(KSNB+N2J))MUNB1=MUNB*X2J/YNBDN2J=((Q1J*N20J+QR2J*RN2J-QTJ*N2J)/VJ)+MUNS1-MUNB1N2J=INTGR(N2IJ,DN2J)

NITRATE NITROGEN

DN3J=((Q1J*N30J+QR2J*RN3J-QTJ*N3J)/VJ)+MUNB1N3J=INTGR(N3IJ,DN3J)

.

ORGANISM (NITROSOMONAS AND NITROBACTER)‚

NITROSONOMASDX1J=((Q1J*XIOJ+QR2J*XR1J-QTJ*X1J)/VJ)+X1J*(MUNS-KDNS)X1J=INTGR(XIIJ,DXIJ)

*‚

NITROBACTER*

DX2J=((Q1J*X20J+QR2J*XR2J-QTJ*X2J)/VJ)+X2J*(MUNB-KDNB)X2J=INTGR(X2IJ,DX2J)

*‚

OXYGEN UTIIZATION BY HETEROTROPIC ORGANISM*

OURC1=Y1P*(RXA1+RSR2)OURC2=Y2P*KDXAOHJ=OURC1+OURC2

OXYGEN CONSUMPTION RATE DUE TO NITRIFIERSONJ=MUNS1*YNS02+MUNB1*YNBO2

OXYGEN INPUT RATE

178

Page 191: Optimal Design and Operation of Wastewater Treatment Plants by

KATJ=KAO+CKAJOURIJ=KATJ*(DOS-DJ)

*‚

DO BAANCEDDJ=((Q1J*DOJ+QR2J*DRJ-QTJ*DJ)/VJ)-OHJ-ONJ+OURIJDJ=INTGR(DIJ,DDJ)

ENDMACRO‚

THIS MACRO CONTAINS MASS BAANCES FOR NON-BIODEGRADABE‚

SOUBE SUBSTRATEMACRO SNJ=ASP1(Q1J,QR2J,QTJ,SNOJ,SNIJ,VJ,SNRJ).

NON-BIODEGRADABE SOUBE SUBSTRATE*

DSNJ=((Q1J*SNOJ+QR2J*SNRJ-QTJ*SNJ)/VJ)SNJ=INTGR(SNIJ,DSNJ)

ENDMACRO

THIS MACRO CAUCUATES RUNNING MEANS AND RUNNING VARIANCESMACRO XBARJ,VBARJ=STAT(XJ,INDEPJ,TRIGJ)

CAC10=MODINT(0 .0,TRIGJ,1 .0,XJ)CAC11=MODINT(O .0,TRIGJ,1 .0,(XJ*-;2))

PROCEDURE XBARJ,VBARJ=OGIC(CAC10,CAC11)IF(INDEPJ) 340,350,340

340

XBARJ=CAC10/INDEPJVBARJ=(CAC11-((CAC10)**2)/INDEPJ)/INDEPJ

350

CONTINUEENDPROCEDUREENDMACRO‚

THIS MACRO MIXES FOWS AND CONCENTRATIONS FOR THE STEP FEED‚

OPERATIONMACRO QT,S,SN,XP,XS,XA,XN,XI,N4,N2,N3,X1,X2,D=STEP( .QTK,QK,SK,SNK,XPK,XSK,XAK,XIK,XNK,N4K,N2K,N3K,X1K,X2K,SOK,SNOK, . . .XPOK,XSOK,XAOK,XNOK,XIOK,N40K,N20K,N30K,X10K,X20K,DK,DOK)*NOSORT

QT=QTK+QKQX1=QTK/QTQX2=1 .-QX1

BYPASS CACUATION IF THERE IS NO MIXING

179

IF(QX2) 10,10,2010 S--SK

SN=SNKXP=XPKXS=XSKXA=XAKXN=XNKXI=XIKN4=N4KN2=N2KN3=N3KX1=X1KX2=X2K

Page 192: Optimal Design and Operation of Wastewater Treatment Plants by

D=DKGO TO 30

20 S=QX1*SK+QX2*SOKSN=QX1*SNK+QX2*SNOKXP=QX1*XPK+QX2*XPOKXS=QX1*XSK+QX2*XSOKXA=QX1*XAK+QX2*XAOKXN=QX1*XNK+QX2*XNOKXI=QX1*XIK+QX2*XIOKN4=QX1*N4K+QX2*N40KN2=QX1*N2K+QX2*N20KN3=QX1*N3K+QX2*N30KX1=QX1*X1K+QX2*X1OKX2=QX1*X2K+QX2*X20KD=QX1*DK+QX2*DOK

30

CONTINUESORTENDMACRO.1.

INITIASTORAGE VS(10),SFUX(10),TFUX(10),A1(10),Z(10)FIXED NEEM,M,NEEM1,I,I1,I2,IFAGD,IFIRST,IEVE,ITMAX,J,IPHFIXED NCE,NEF,ITER,NP,NP2

CARBONACEOUS PARAMETERSPARAM KT=0 .0125,FSH=0 .7,RS=0 .002,K=150 .,KD=0 .015PARAM Y1=0 .6,Y2=0 .2,Y3=1 .O,RH=0 .015PARAM SI1=24 .,SI2=8 .2,SI3=3 .6,SNI1=10 .0,SNI2=10 .0,SNI3=10 .0PARAM XNI1=179 .,XNI2=179 .,XNI3=179 .,XAI1=570 .,XAI2=570 .,XAII1=100 .PARAM XAI3=570 .,XII1=445 .,XII2=445 .,XII3=445 .,XSI1=150 .,XSI2=115 .PARAM XSI3=45 .,XPI1=285 .,XPI2=280 .,XPI3=275 .PARAM XA01=0 .0,XS01=0 .0,MSS=2500 .0PARAM FRACV=0 .79,FRACB=0 .70,KOEX=1 .5,KOES=0 .63,FRACB1=0 .8PARAM FRAC4=0 .4,FRANV= .21,FRANB= .3,XMTI1=0 .0

NITROGENEOUS PARAMETERSPARAM MUHNS=0 .02,KSNS=1 .0,MUHNB=0 .04,KSNB=1 .0,KDNS=0 .005PARAM KDNB=0 .005,YNS=0 .05,YNB=0 .02,KN=0 .07PARAM N2I1=0 .5,N2I2=0 .5,N2I3=0 .5,N4I1=13 .9,N4I2=9 .4,N4I3=5 .9PARAM N311=7 .1,N3I2=10 .5,N3I3=13 .75,N301=0 .0,N201=0 .0PARAM X1I1=6 .3,X112=6 .3,X1I3=6 .3,X101=0 .0PARAM X211=2 .4,X2I2=2 .4,X2I3=2 .4,X201=0 .0PARAM YNS02=3 .42,YNB02=1 .14PARAM NEEM=10,HCAR=3 .048,FA=1 .8052,QII=4 .,VD=900 .PARAM ROW=0 .3,SRT=10 .,MXTS=O .O,QI=4 .0PARAM SNH4AV=30 .0,SCODA=250 .0,TSSAV=150 .PARAM T1=24 .,T2=24 .,T3=6 .,TDE=0 .025,DTIME= .25,CKG=1 .E+03PARAM TPRED=2 .,ITYPE=3,ESP=0 .001,KSP=0 .05PARAM FGATE1=1 .,FGATE2=0 .,FGATE3=0 .,RGATE1=1 .,RGATE2=0 .,RGATE3=0 .PARAM QAV=788 .55,XEFF=17 .975,SAGE1=9 .PARAM ABO=83 .1,AB1=-7 .19,AB2=-3 .33,AB3=-1 .50,AB11=-0 .626PARAM AB22=-0 .304,AB33=0 .014,AB12=1 .44,AB13=0 .132,AB23=0 .024PARAM IFAGD=2,HEIGHT=4 .0,PPUMPF=3 .,REFFP=0 .2

**

180

Page 193: Optimal Design and Operation of Wastewater Treatment Plants by

J.

J.

PARAM CXTPU=5 .0E04,IXNPU=8 .E06,IXVPU=35 .OE06PARAM SSI=150 .,BOD5=250 .,NH4=25 .,THETAH=6 .0PARAM XR=10000 .PARAM OFR=800 .,POFR=850 .PARAM OMEFFT=0 .05,PUMPT=4 .,CXTTU=1 .E+05PARAM IMTNVS=1 .E+03,IMTBD=1 .E+03,IMTNB=1 .E+03,ITMSIT=1 .E+08PARAM AGT=400 .PARAM CONBD=0 .7,CONNB=0 .30,CONNV=0 .21

DISSOVED OXYGEN PARAMETERS

PARAM CKA1=20 .0,CKA2=20 .0,CKA3=20 .O,KAO=0 .1PARAM DR1=O .O,DO1=0 .O,DOS=8 .0PARAM DI1=4 .0,DI2=4 .O,DI3=4 .0

1

*

COST AND OPTIMIZATION PARAMETERS

PARAM CKWH=0 .05,CO=10000 .0,CSD=20 .O,DHR=20 .84,HEAD=3 .0PARAM IFIRST=1,IEVE=-1,DBTIME=0 .0

PARAM SUMOD=1 .E+14,EPS=1 .E+35,EPSI=0 .10PARAM ITMAX=4,DP=0 .1,ITER=OPARAM AINR=0 .08,IPH=20,FVOPC1=0 .0,EFFG=0 .6

PARAM FAGC=1 .,FAGO=1 .

INITIA SEGEMENT OF THE REACTORNEF=3NCE=11NP=5NP2=10S3C=SI3XA3C=XAI3XP3C=XPI3XS3C=XSI3XI3C=XII3XT3C=XA3C+XP3C+XS3C+XI3CXN3C=XNI3X13C=X113X23C=X213XAR=XAI3/ROWXPR=XPI3/ROWXSR=XS13/ROWXIR=XII3/ROWXTR=XAR+XSR+XPR+XIRX1R=X113/ROWX2R=X213/ROW

NOSORT

PRIMARY AND SECONDARY CARIFIER OVERFOW RATES ARE IN M**3/M**2/DAY WHEN USED IN THE OPTIMIZATION PROGRAMPAR(1)=400 .PAR(2)=9 .

141

Page 194: Optimal Design and Operation of Wastewater Treatment Plants by

PAR(3)=5 .5PAR(4)=300 .PAR(5)=400 .PARU(1)=1200PARU(2)=20 .0PARU(3)=15 .PARU(4)=2500 .0PARU(5)=700 .DO 101 I=1,NEEMTFUX(I)=0 .0SFUX(I)=0 .0A1(I)=0 .0Z(I)=DX%`I

101

CI(I)=800 .CI(NEEM-1)=4000 .CI(NEEM)=8000 .CU=CI(NEEM)

SORTGAMMA=((1 .-(1 .+AINR)**(-IPH)))/AINRQO=QAVN401=SNH4AVQPP=QO5011=SCODA*(1 .-REFFP)S012=SO11/KOESS01=S012*FRAC4SN01=FRANB*SO1STIME=0 .0SSIN=TSSAVXPOO=SS IN*FRACV*FRACB*KOEXXIOO=SS IN*FRACV*FRANB*KOEXXNOO=SS IN*FRANV**KOEXFN=0 .0Y1P=1 .-Y1Y2P=1 .-Y2YSB=YNS02+YNBO2RXA=K*RSDX=HCAR/NEEMM=NEEM-1V1=V/3 .V2=V1V3=V1

PROCEDURE AREAP,V,THETAH,A3,FUX,XAI1,XAI2,XAI3,XPIl,XPI2,XPI3, . . .XII1,XII2,XII3,XSII,XSI2,XSI3,XNI1,XNI2,XNI3,X1I1,X1I2,X1I3,X2I1, . . .X2I2,X2I3,XTI1,XTI2,XTI3,THETAD=STD1(SSI,BOD5,NH4,XR,VD, . . .QII,POFR,OFR,ROW,SRT,TSSAV,SCODA,MSS)

IF( IFIRST .GT .1) GO TO 200PAROD(1)=POFRPAROD(2)=SRTPAROD(3)=THETAHPAROD(4)=VDPAROD(5)=OFRCA STEADY(SSI,BOD5,NH4,AREAP,V,SRT,THETAH,QAV,XR, . . .

A3,THETAD,VD,QII,MSS,POFR,OFR,IFIRST)

182

Page 195: Optimal Design and Operation of Wastewater Treatment Plants by

IFIRST=IFIRST+1GO TO 210

200 POFR=PAROD(1)SRT=PAROD(2)THETAH=PAROD(3)VD=PAROD(4)OFR=PAROD(5)CA STEADY(SSI,BOD5,NH4,AREAP,V,SRT,THETAH,QAV,XR, . . .

A3,THETAD,VD,QIIIA,MSS,POFR,OFR,O)‚

CA SICOND(TSSAV,BOD5,SRT,XAI1,XAI2,XAI3,XSI1,XSI2,XSI3, . . .‚

XPI1,XPI2,XPI3,XII1,XII2,XII3,XNI1,XNI2,XNI3,X1I1,X1I2,X1I3, . . .‚

X21l,X2I2,X2I3,XTI1,V,THETAH)210 CONTINUEENDPROCEDURE

DYNAMIC

DYNAMIC SEGMENTTRG6=0 .5-IMPUS((T3+TDE),T3)TRG24=0 .5-IMPUS((T1+TDE),T1)TRG168=0 .5-IMPUS((T2+TDE),T2)T6=MODINT(O .0,TRG6,1 .0,1 .0)T24=MODINT(O .0,TRG24,1 .0,1 .0)T168=MODINT(O .0,TRG168,1 .0,1 .0)

INPUT SECTION TO THE MODEPROCEDURE QO,QPP,SSIN,SO1,N401,XIOO,XNOO,XPOO,SO11,SO12,DIFF1,XAAI2= .INPUT(ITYPE,T6,T24,T168,FRACV,FRACB,KOEX,FRACB1,KOES,SNH4AV)

IF(IFAGD .EQ .1) FA=0 .0IF(KEEP-1) 3060 ;3000,3060

3000 IF(TIME-STIME) 3060,3010,30103010 STIME=TIME+DTIME

XAAI2=XA1DIFF1=ABS(XAAI2-XAII1)IF( DIFFI .T .ESP) FN=1 .0XAII1=XAAI2IF(ITYPE-2) 3020,3060,3060

a

TIME VARYING INPUT3020 SSIN=TSSAV*TSS(T24)

5011=SCODA*VBOD(T24)*(1 .-REFFP)S012=SO11/KOESS01=S012*FRAC4SN01=FRANB*SO1N401=SNH4AV*VSNH4(T24)XPOO=SSIN*FRACV*FRACB*KOEXXIO0=SSIN*FRACV*FRANB*KOEXXNOO SSIN*FRANV*KOEXQO=QAV*FOW(T24)QPP=QAV*FOW(T24+TPRED)

3060 CONTINUEENDPROCEDURE

183

Page 196: Optimal Design and Operation of Wastewater Treatment Plants by

i81

Txb-€b=xboxb-Txb=zxb

Tb;:Id=OxbTb*(Id+MO1)=Txb

zb=€bTb;:(Mox+'T)=zb

Ib-ivb=Tb(daX-nO) / (ddaX- (,HSH/WnN))=Id

t zIvb..nIs=jusvVd+ob=iVb

SNOO=€.SNOOVH0;‚c,HH*

'€ Zg5'+(Zm;=H2I0);=€ € g~'+(Z;=x2IH);=ZZHt~+~'2I0=~€ S~l+,2IH;=Z g5'+0 g~=T.SN00VHO;-€TgV+J IHTZTgel+T g5'=Z.SNOO

SJXN+SSAZW*A=WnN'~zTc€~/xa)=~xo

HVJ 2H.=.HHO€NX+SSA'IW=SS'IN

O€ZX+O€TX+O€,X=SSNIWO€IX+O€vX+O€dX+O€SX=O€,X

NH`HWI1NOII.Na.aIOI'InV2IUAH:HH

;AHa/SHH,aN `av2I MOgdXaAO:V10

TS.kva `HW NONHJISQI'IOS:.2IS

ZT;-W'2IH/DX NISIXf'3 aNV

r` Z;-;-WNISIHHNV'2IH/€*rW NISI Mad

HHIfIUWIO AHVGNOOHS

r

HxnGHOOHdGNa(NISS`dvaiv'HOIaH`IHb`Mod`In Na'I`Td33HX)TQSd 'IlIHO

(2IIod`NISS`dVa2IV`JHDIHH`IVb)aSd=H.DNaU'TdddgX H2In([UDOHd(ndnxa`ndAXI)'Ixo,NI=ndAX

adAX Ib-HH*AOVId NISS;=AVb=ndAXU(ndNXa`ndNXI) rfID.N I=ndNX

ndNXO;:Ib-H?I;:ANv Id NISS;:AVb=ndNXa(nd.XOTdva2Iv) / (ndAX+ndNx)=SdSH

ndNXO-ndZXO=ndAXO((ndnx+ndNx)/ndNX)Tnd.x3=ndNXO

XNVI NOIZVZNaNIGaS ANVWI2Id HHZ NI aJan'SJO.HDIaH =SdSH;~NOVNINHONOO MO'IJZIHQNfr

XHO)IkANV Id,.nOSS=IONXXHON$aNH2idrA Ov2I3;=.nOS S=T O I XXaOX*gDVHd AOV2I3-;.nOSS=TOdX

NISS (aI-'T)=.noSSNISS/(TdddaX-NISS)=H1

2IHIdfIV'IO AHVNIHd HIU 30 AONHIOI33HMOM:aH

NOIZvnba NOISn33Ia-NOIZOHAIH SIHZJO.'InSaN SI DNISn aadO'IaAaaSINOIZBnbH 'IvOINIdwH aHZ aNY GOH,HW

(Iav).IOI'IdWI NOOH2IIa DNVNHH.'IH ONISn a2A'IOSSINOIlvnba;~NOISnJdIa-NOOHAaV 'IVNOISNaWIG OM.)JNHWDHS ?IaIdI21WIO ANVWfId;~

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Page 197: Optimal Design and Operation of Wastewater Treatment Plants by

VEOCITY IS IN CM/HOUR,‚

AREA IS IN M**2 AND CONCENTRATION IS IN GM/M**3BODEFF=(S3C+XEFF*((XA3C+XS3C+XP3C)/XT3C))`KOESC=INTGR(CI,CDOT,10)

PROCEDURE CDOT,TFUX,SFUX,THETA,VS,A,A2,SAGE1,SAGE2=SEC2(MXTS, .MSS,MVSS,XT3C,Q3,QR1,A3,QR,XEFF,DX,NEEM)

A=A3U=QR1*100 ./AFUXIN=(Q3*MSS-(Q3-QR1)*XEFF)*0 .001/ADO 1000 I=1,NEEMVS(I)=SVS(C(I))

1000 SFUX(I)=(C(I)*VS(I))*0 .00001TFUX(1)=(U`C(1))*0 .00001+AMIN1(SFUX(1),SFUX(2))CDOT(1)=(FUXIN-TFUX(1))*1000 ./DXDO 1010 1=2,MTFUX(I)=(U*C(I))*0 .00001+AMIN1(SFUX(I),SFUX(I+1))

1010 CDOT(I)=(TFUX(I-1)-TFUX(I))*1000 ./DXCDOT(NEEM)=(TFUX(M)-(U*C(NEEM)*0 .00001))1000 ./DXTFUX(NEEM)=(U*C(NEEM))*0 .00001+SFUX(NEEM)A2=ATHETA=0 .0MXTS=0 .0DO 1050 I=1,NEEMMXTS=MXTS+DX*A2*C (I)

THETA IS IN HOURS1050 THETA=THETA+DX*100 ./(VS(I)+U)

IF (TSWR) 2010,2010,2005‚

TSWR IS IN GMS/HR, SAGE1,SAGE2 ARE IN DAYS .2005 SAGE1=MTA/(TSWR*24 .)

SAGE2=MT/(TSWR*24 .)2010 CONTINUEENDPROCEDURE.l .

RECYCE SUDGE CONCENTRATIONVE=HCAR*100 ./THETAXPRP=PIPE(250,XPI3,HCAR,VE,XP3C,1)XARP=PIPE(250,XAI3,HCAR,VE,XA3C,1)XSRP=PIPE(250,XSI3,HCAR,VE,XS3C,1)XIRP=PIPE(250,XII3,HCAR,VE,XI3C,1)XTRP=XPRP+XSRP+XARP+XIRPX1RP=PIPE(250,X1I3,HCAR,VE,X13C,1)X2RP=PIPE(250,X2I3,HCAR,VE,X23C,1)XNRP=PIPE (250,XNI3,HCAR,VE,XN3C,1)MSSRP=XTRP+XIRP+X2RP+XNRPMVSRP=MSSRP-XNRP

PROCEDURE XAR,XPR,XSR,XIR,XTR,XNR,XIR,X2R,SRI,SNR1,MSSR,RN41,RN31, . . .RN21,MVSSR,FAC1,XTRDI,MTNVS,MTBD,MTNB,TMSIT,HST,XNVO1,BDO1, . . .NBDO1,PRIMC2=THICK(XARP,XSRP,XPRP,XIRP,XNRP,XIRP,X2RP,FA,QII, . . .XTRP‚

,MSSRP,MVSRP,C(NEEM),CXTPU,CONBD)

THIS PROCEDURE IS USED FOR THE SIMUATION OF GRAVITY SUDGETHICKENER INCUDING THE MIXING OF THICKENER RETURN SUPERNATANT

185

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.1.

510515

520.

*

HIGH RATE DIGESTION WITH THICKENER SUPERNATANT RECYCEDMTNVS=QI*CONNV*CXTPU+C(NEEM)*FRANV*QRO-FA*OMEFFT*C(NEEM)*FRANVMTNVS=INTGR(IMTNVS,DPTTNVS)DMTBD=QI*CONBD*CXTPU+C(NEEM)*FRACB*QRO-FA*OMEFFT*C (NEEM)*FRACBMTBD=INTGR(IMTBD,DMTBD)DMTNB=QI*CONNB*CXTPU+C(NEEM)I . FRANB*QRO-FA*OMEFFT*C(NEEM)*FRANBMTNB=INTGR(IMTNB,DMTNB)TMASS=MTNVS+MTBD+MTNBDTMSIT=QI*CXTPU+C(NEEM)*QRO-QII*CXTTU-FA*OMEFFT*C(NEEM)TMSIT=INTGR(ITMSIT,DTMSIT)HST=TMSIT/(AGT*CXTTU)PRIMC2=IMPUS(0 .0,6 .0)QII=PUMPT*INSW((HST-1 .),0 .,1 .)*PUSE(2 .,PRIMC2)IF(QIIIA .EQ .0 .0) GO TO 540XNV01=DMTNVS/QIIIABD01=DMTBD/QIIIANBD01=DMTNB/QIIIAGO TO 550XNV01=0 .0BDO1=0 .0NBD01=0 .0FA1=QRO+QI-QIIFA=INSW(FA1,0 .,FA1)SR1=S3CSNR1=SN3RN41=N43RN21=N23RN31=N33GO TO 515

530 CONTINUEENDPROCEDURE

QIIIA,QIIIV=STAT(QII,T24,TRG24)*

FOW DIVIDE SEGMENTTHIS PROCEDURE DIVIDES THE INFUENT AND RECYCE FOWS FOR STEPFEED

540

550

GO TO (510,520),IFAGDOW RATE DIGESTION WITHOUT THICKENERXTRDI=C(NEEM)FAC1=C (NEEM)/MSSRPXAR=FAC1*XARPXSR=FAC1*XSRPXPR=FAC1*XPRPXIR=FAC1*XIRPXTR=FAC1*XTRPXNR=FAC1*XNRPX1R=FAC1*X1RPX2R=FAC1*X2RPMSSR=FAC1*MSSRPMVSSR=FAC1*MVSRPGO TO 530CONTINUE

186

Page 199: Optimal Design and Operation of Wastewater Treatment Plants by

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Page 200: Optimal Design and Operation of Wastewater Treatment Plants by

EFFUENT TSS CONCENTRATIONXEFF=CONST3+CONST2-`SAGE1+AB11-`(SAGE1**2)IF(XEFF .T .O .0) XEFF=4 .5+4 .2*(MSS*QR*0 .001/A2)

ENDPROCEDURE*NOSORT‚

CA DEBUG(1,DBTIME)*SORT

INVENTORY SECTION OF THE MODE‚

OXYGEN CONSUMPTION CACUATIONSIN1=(XIOI+XPO1+SO1+(N401+KN*XI01)*YSB)*QOOUT11=(S3+N43*YSB)*QROUT21=(S3+XTR+XIR+X2R+YSB*KN*(XAR+XIR))*QROXM1=(IN1-OUT11-OUT21-OCRT)/CKGXMT1=INTGR(XMTI1,XM1)OT1=0H1+ON1OT2=0H2+ON2OT3=OH3+ON3OTN=ON1+ON2+ON3OTH=OH1+OH2+OH3OCRH=OTH*V1OCRN=OTN-'V 1OCRT=OCRH+OCRNa

OC,OCH AND OCN ARE IN KG .OC=MODINT(O .0,TRG24,1 .0,OCRT/CKG)OCH=OC-OCNOCN=MODINT(O .0,TRG24,1 .0,OCRN/CKG)

.1.

SUDGE MASS AND RECYCE CACUATIONMSSRA=MODINT(O .0,TRG24,1 .0,MSSR)

SWR,VSWR,ESWR ARE IN GMS/HR AND MT1,MT2,MT3 ARE IN GMS .SWR=QRO*MSSRVSWR=QRO*MVSSRNVSWR=SWR-VSWRSWT=MODINT(O .0,TRG24,1 .0,SWR)VSWT=MODINT(O .O,TRG24,1 .0,VSWR)NVSWT=SWT-VSWTESWR=(Q3-QR1)*XEFFEVSWR=ESWR'*MVSS/MSSENVSWR=ESWR-EVSWRESWT=MODINT(O .0,TRG24,1 .0,ESWR)EVSWT=MODINT(0 .0,TRG24,1 .0,EVSWR)ENVSWT=ESWT-EVSWTTSW=SWT+ESWTTSWR=SWR+ESWRTNVSW=TSW-TVSWTVSW=VSWT+EVSWTMT1=(XT1+X11+X21+XN1)*V1MT2=(XT2+X12+X22+XN2)*V2MT3=(XT3+X13+X23+XN3)*V3MTA=MT1+MT2+MT3

188

Page 201: Optimal Design and Operation of Wastewater Treatment Plants by

MTNVA=XN1*V1+XN2*V2+XN3*V3MT=MTA+MXTSMTT=MODINT(0 .0,TRG24,1 .0,MT)CU=MSSRBDPBN=BD1+BN1PRIMC1=IMPUS(O .0,4 .0)QI=PPUMPF%`INSW((HSPS-1 .0),0 .,1 .)*PUSE(2 .,PRIMCI)Q4MT1=MODINT(O .O,TRG24,1 .O,Q4MT)QIIAV1=MODINT(O .O,TRG24,1 .0,QIIIA)BDPBN1=MODINT(O .O,TRG24,1 .0,BDPBN)

NOSORTCA DEBUG(1,DBTIME)S3C=S3SN3C=SN3XA3C=XA3XS3C=XS3XP3C=XP3X13C=XI3XT3C=XT3XN3C=XN3X13C=X13X23C=X23

TERMINAOURTA=OC/T24Q4MTA=Q4MT1/T24QIIAV2=QIIAV1/T24BDPBN2=BDPBN1/T24

PRINT S1,SN1,N41,N21,N31,XP1,XS1,XA1,XI1,XN1,X11,X21,XT1, . . .OH1,ON1,OT1,D1,S2,SN2,N42,N22,N32,XP2,XS2,XA2,XI2,XN2,X12, . .X22,XT2,OH2,ON2,0T2,D2,S3,SN3,N43,N23,N33,XP3,XS3, . . .XA3,XI3,XN3,X13 ;X23,XT3,OH3,ON3,OT3,D3

OUTPUT PI,QO,Q1,Q2,QR,QX,QRX,QRY,QRZ,QRO,QR2,QAI,QI,QII,QIIIA, . . .FA,OTH,OTN,OCRT,OCRN,OC,OCN,SWR,VSWR,NVSWR,SWT,ESWT,TSWR, . .TSW,MTA,MTNVA,MXTS,MT,HRT,ORA,A2

OUTPUT XPR,XAR,XSR,XIR,XTR,XIR,X2R,SAGE1,SAGE2,XEFF,RE, . . .SSOUT,XPO1,XIO1,XNO1,XEFFP1,BODEFF,FACI,C(1-10), . . .BDO1,NBDO1,XNVO1,VD,OR1,Q4MTA,TACID,BD1,BN1,XNCD1,PVSSDTIMER FINTIM=1 .,DET=0 .02,PRDE=1 .0,OUTDE=I .O,DEMIN=0 .25E-10*FINISH FN=1 .METHOD TRAPZ

IF((FAGC .T .1 .0) .AND .FAGO .GT .0 .0) GO TO 601IF((FAGC .GT .O .0) .AND .FAGO .GT .0 .0) GO TO 601OCRT = QAV*(BOD5*1 .5 + NH4*4 .5)

601

CA COST(CCOST,OM,VOPC,OURTA,OCRT,BDPBN2, . . .QO,V,AREAP,BCAP,A3,AGT,QR1,QI,Q4MTA,QIIIA,VD,CKWH,CO, . . .CSD,DHR,HEAD,VOPC1,EFFG)IF( IEVE .GT .O) GO TO 145DO 605 I=1,NEF

605

WEIGH(I)=1 .DO 610 I=1,NCEER(I,1)=(CCOST(I)/GAMMA)*FAGCER(I,2)=OM(I)*FAGOER (I ,3)=0 .0

189

Page 202: Optimal Design and Operation of Wastewater Treatment Plants by

610

CONTINUEER(5,3)=VOPC*FAGOER(7,3)=(VOPC1+FVOPC1)*FAGODO 620 J=1,NEFSUM=0 .0DO 625 I=1,NCE

625

SUM=SUM+ABS(ER(I,J))620

ERP(J)=SUM*WEIGH(J)SUM=0 .0DO 640 J=1,NEF

640

SUM=SUM+ERP(J)WRITE(6,9191)

*9191 FORMAT(10X,'******CAPITA COSTS ******')WRITE(6,9192) (ER(I,1),I=1,NCE)

*9192

FORMAT(10X,5E15 .5)WRITE(6,9193)

*9193 FORMAT(/10X,'***** OPERATING COSTS **** * ')WRITE(6,9194) (ER(I,2),I=1,NCE)

*9194

FORMAT(/10X,5E16 .5)WRITE(6,9195)

*9195

FORMAT(/10X,'-`*** VARIABE OPERATING COSTS,.***,.')WRITE(6,9196) (ER(I,3),I=1,NCE)

*9196

FORMAT(/10X,5E17 .5)*

WRITE OUT THE SUMWRITE(6,1041) SUM

1041 FORMAT(' TOTA ERROR = ',E17 .6)ITER=ITER+1WRITE(6,1039) ITER

1039

FORMAT(/10X, 'ITER=',I3)

CHECK FOR ABSOUTE CONVERGENCEIF(SUM-EPS) 110,110,120

110

WRITE(6,1042)1042 FORMAT(' EXECUTION TERMINATING DUE TO ABSOUTE CONVERGENCE')*

CHECK FOR ERROR IMPROVEMENTGO TO 500

120

IF(ABS(SUMOD-SUM)-EPSI) 130,130,133130

WRITE(6,1045) SUMOD,SUM,ITER1045 FORMAT(' EXECUTION STOPING DUE TO FAIURE TO IMPROVE ERROR', .

/,' SUM OD=',E17 .6,5X,'SUM=',E17 .6,'ITER=',I3)GO TO 500

*

* CHECK TO SEE IF THE MAXIMUM NUMBER OF ITERATIONS IS EXCEEDED133

IF(ITMAX-ITER) 135,140,140135

WRITE(6,1046) ITMAX,ITER1046 FORMAT(' THE MAXIMUM NUMBER OF ITERATIONS IS EXCEEDED', .

/,' ITMAX=',I4,5X,'ITER=',I4)GOTO 500

SAVE THE VAUE OF SUM FOR FUTURE ITERATIONS140

SUMOD=SUM

190

Page 203: Optimal Design and Operation of Wastewater Treatment Plants by

REA KD,KS,KDN,KSN,MADPTH,MSR,MUH,MUHN,MCONT,NH4,NH4E,MSS

STEADY STATE DESIGN OF ACTIVATED SUDGE TREATMENT PANTDATA BODE/20 ./

CC

CONSTANTS FOR THE DESIGN OF ACTIVATED SUDGE PANTDATA KD/ .06/,MUH/5 .0/,YIED/0 .6/,KS/60 .0/,BOD5BU/ .68/,1FRAC/1 .42/

CC

CONSTANTS IN CASE OF NITRIFICATIONDATA KDN/ .005/,KSN/1 .0/,MUHN/0 .4/,NH4E/1 .0/

CDATA VSBTS/ .70/,MADPTH/5 .0/,RSS/0 .5/,RBOD5/ .25/,1DTIME2/3 .5/,DCARP/10 .0/,SPGSG/1 .03/,MCONT/ .94/,2DTIMPI/2 .0/,DCAP/10 .0/CONS=4 .536E+05

y

145

BEGIN PUTURBATIONSIEVE=1PSAVE=PAROD(IEVE)PTURB=PAROD(IEVE)%DPPAROD(IEVE)=PAROD(IEVE)-PTURBCA RERUNGO TO 500

CACUATE INFUENCE COEFFICIENTPAROD(IEVE)=PSAVE

170

DO 170 I=1,NCECINF(1,IEVE,I)=FAGC*(ER(I,1)-(CCOST(I)/GAMMA))/PTURBCINF(2,IEVE,I)=FAGO*(ER(I,2)-OM(I))/PTURBCINF(3,IEVE,I)=0 .0

490

CINF(3,IEVE,5)=FAGO*(ER(5,3)-VOPC)/PTURBCINF(3,IEVE,7)=FAGO*(ER(7,3)-(VOPC1+FVOPC1))/PTURBIEVE=IEVE+1IF( IEVE .GT .NP ) GO TO 490PSAVE=PAROD(IEVE)PTURB=PAROD(IEVE) *DPPAROD(IEVE)=PAROD(IEVE)-PTURBCA RERUNGO TO 500WRITE(6,1213)

1213 FORMAT(//10X,'STARTING THE OPTIMIZATION PROCEDURE')

500

CA OPTIM5(PAROD,PAR,PARU,WEIGH,CINF,ER,ERP,NP,NP2,NEF, . . .NCE,NCE,ITER,2,1)

DBTIME=0 .0IEVE=OCA RERUNCONTINUE

ENDSTOP

1SUBROUTINE STEADY(SSI,BOD5,NH4,AREAPC,V,THETAC,THETAH,FOW2,XR,

AREAS,THETAD,VD,QII,MSS,POFR,OFR,IFIRST)C

Page 204: Optimal Design and Operation of Wastewater Treatment Plants by

CC

CCC

CONSI=CONS*0 .03531CONS2=24 . *7 .48CONS3=10 .76391BOD5IA=BOD5*RBOD5FOW1=FOW2*6340 .1FOW=FOW1/1 .E+06FOW2=FOW*3785 .4/24 .

EFFUENT BOD=INFUENT BOD5 ESCAPING TREATMENT +BOD5 OF EFFUENTSUSPENDED SOIDSBOD5EF=BOD5E*FRACBUBOD=BOD5EF*FRACBOD5ES=UBOD*BOD5BU

CC

INFUENT SOUBE BOD ESCAPING TREATMENTSBODE=BOD5E-BOD5ES

CC

EFFICIENCY BASED ON SOUBE BUDSTEFF=((BOD5-SBODE)/BOD5)*100 .

CC

OVERA PANT EFFICIENCYEOVER=((BOD5-BOD5E)/BOD5)*100 .VO=FOW*THETAH/24 .V=VO*3785 .4XV=MSS*VO*8 .34SPROD=XV/THETAC

CC

BY MATERIA BAANCE IN THE CARIFIERQR=FOW*MSS/(XR-MSS)QW=VO*MSS/(THETAC';XR)FDM=FOW*8 .34'^(BOD5-SBODE)/XV

CC

02 REQUIREMENT(WITHOUT CONSIDERING NITRIFICATION, IN TERMS OF COD)C

02 DEMAND IN = UNTREATED 02 DEMAND+OXIDIZED 02 DEMAND+02 DEMANDC

OF SUDGE02DH=(FOW*8 .34*(BOD5-SBODE)*1 .47-SPROD*FRAC)* .4536

02 DEMAND CONSIDERING NITRIFICATION(FOR THETAC>5 DAYS)02DN=(FOW*(BOD5-SBODE)*8 .34*1 .47+4 .55*FOW*8 .34*(NH4-NH4E)-

11 .98*SPROD)* .4536CC

SECONDARY CARIFIERAREA1=FOW1/OFRAREAS=AREA1/CONS3XTSS=MSS/VSBTSFUX=(FOW+QR)*XTSS*8 .34/AREA1

CC

ESTIMATE REQUIRED DEPTH FOR THICKENINGC

DETERMINE THE MASS OF SOIDS IN THE AERATION BASINABSOD=VO*XTSS*8 .34CSAV=(MSS+XR)/(0 .8*2 .)

CC

DEPTH OF SUDGE ZONE IN THE SEDIMENTATION BASIN

192

Page 205: Optimal Design and Operation of Wastewater Treatment Plants by

MSSB=0 .3*ABSODDEPTH1=(MSSB/(AREA1*CSAV))*CONS1PEAKQ=2 .5 %`FOWPKBOD=1 .5*BOD5XV1=(YIED€PEAKQ*(PKBOD-SBODE)*8 .34)/(1 .+KD*THETAC)QWXW=XV1TSOID=QWXW+MSSBDEPTH2=(TSOID/(AREA1*CSAV))*CONS1TRDPTH=MADPTH+DEPTH1+DEPTH2TRDPT=TRDPTH* .3048DTIME1=(AREA1*TRDPTH*CONS2)/FOW1

CC

ATERNATE APPROACHC

ASSUMING DETENTION TIME=3 .5HOURSVO2=FOW1*DTIME2/CONS2VOS=VO2/35 .3147AREA2=VO2/DCARPAREAA=AREA2/CONS3

CC

PRIMARY SEDIMENTATION TANKAREAP1=FOW1/POFRAREAPC=AREAPI/CONS3FUXP=(FOW*8 .34*SSI)/AREAP1MSR=RSS*SSI*FOW*8 .34VOSG=MSR/(SPGSG*8 .34*(1 .-MCONT))DSISB=VOSG/(AREAPI*7 .48)DEPTP=MADPTH+DSISBDTIMEP=AREAPI*DEPTP*CONS2/FOW1

CC

ATERNATE APPROACHVOP=FOW1*DT IMPI/CONS2AREAP2=(VOP/DCARP)/CONS3

CC

COMPUTE THE DIGESTER SOID RETENTION TIMEC

IF(QII .E .O .0) GO TO 123THETAD=VD/(QII*24 .)

123

IF(IFIRST .GT .1) GO TO 995WRITE (6,900)

900 FORMAT(1H1,///20X,'STEADY STATE DESIGN OF ACTIVATED SUDGE TREAT',1' MENT PANT')WRITE(6,910) SSI,BOD5,NH4

910 FORMAT(//20X, 'INFUENT SUSPENDED SOIDS CONCENTRATION=',F8 .2,1/20X, 'INFUENT BIOCHEMICA OXYGEN DEMAND=',F8 .2/20X, 'INFUENT ',2'AMMONIA CONCENTRATION(MG/)=',F8 .2)WRITE(6,920) MUH,KD,YIED,KS,BOD5BU

920 FORMAT(/20X, 'SPECIFIC GROWTH RATE=',F10 .5/20X, 'DECAY COEFFICIENT='1,F10 .5/20X,'YIED COEFFICIENT--',F8.4/20X, 'SATURATION COEFFICIENT',2'IN MG/ BOD5=',F8 .4/2QX,'BOD5/BODU=',F5 .3)WRITE(6,930) RSS,RBOD5

930 FORMAT(/20X,'REMOVA OF SUSPENDED SOIDS IN PRIMARY CARIFIER=',1F5 .2/20X,'REMOVA OF BIOCHEMICA OXYGEN DEMAND=',F8 .4)WRITE(6,940) FOW,FOW2

1 93

Page 206: Optimal Design and Operation of Wastewater Treatment Plants by

I6T

QN3N2Tn.32I

3f1NIZNO3

OT(I)Av nIv=XvWI

OTOZ00(XVW3'.'I' (I)AVnJv)dIN'Z=IOTOQ

(T)XH2i2IV=XVNd(T)AvnIv N0ISN8WIQ

S2I3HWf1N 30 Wf1WIXVW 3HZ 3 WIflYIHO01

3OO

(N`Afl2I2Iv)XVWd NOONIIdQN3

MUM566(////5' •T3` ,_(• ~rw)2IHZSHOIQ aHZ 30 SWfl'IOA,`XOZ/*I'83 '7

,=3W NON13Q 2IaSa0IQ, `X0Z/*7'8d`,=(2TH/•*;:W)MO'IdNI 2I3.SaoIQ, •`XOZ/////t' 8d` ,=(S2IfloH)2IaIdI2tv'IO M1VcIN0O3S 3HZ 30 3WIZ NONaZ3Q,Z

`XOZ/5' •T3` ,=(Z*;:W)2I3IdI2iv'ID AIVNO3S3HZJOVIH,`XOZT`/5' •T3` ,=(caw)2TaIdnIv"ID M1V(IN0O3S 30 3W YIOA, `XOZ/).VN?TOdMT

QA`QVZ3H.`IIa`ZaNQ`V'32V's'IOA (0'10i`9)3,I2IM(,2IaIdnIv'13 A IVQNOD3S 2IOd H3V02IddV a.VN2I3'IV, `X0Z//)1.VJ4e!Od0•01

(0•OT`9)3ZI2IMW8d`,=(S2If10H)3W NON3.aa,`X0Z/*l'8d` ,=(Z33d)2IaIdnivrO, Z

,MIVcIN0O3S 3HZ 30 1d['IVZO., `XOZ/t' 8d` ,=AVQ' Zr,-.3/H'I NI Xfl'I3, i`XOZ/`5' •T3` ,=(Za:,=W)2IaI3niv'IO X2IVQN003S 3HZ 30 V32IV,`XOZ/)1vwIOdOZOT

TaNIZQ`HZdU2'Xfl'Id`SVaIV (OZOT`9)aI2IM(,2IaIdnIv13 A IVGN0O3S 3HZ 30 SaII'IvA QaNDISaQ, `XOZ//)ZvbRIOdOTOT

(0T01'9)1I1(5' •T3` ,=(Z/DW)Nov2Na3NOO 'IVIH02IOIW N2Iaa r, `XOZ)Zvw2IOdSOOT

2TX (SOOT`9)3ZI2IMCS'•T3`,=(AvQ/ZO OM)Nov3IdniINJO3SV3 NI,9

,QNVWaU NaUAX0,`XOZ/5'•T3`,=(xvQ/ZO oN)SHd0202I3.aH xH QNvwau ,5`,NaDXX0,`XOZ/*l'8d`,=(Sxva)3W NON3aI 3OQfflS,`XOZ/1'8d',=(SA,t

`,H(I)3W NON31.3Q OI'If1V2IQAH, `X0Z/t'8d` ,=WSINV0IO-02IOIW/0003,`XOZ•/5' •T3` ,=(Z/DW)NISVH NOIZ'72IaV 3HZ NI NOIV N3ONOD 'IVIH02IOIW,`XOZZ/''8d` ,=(QDW) 3.v2I MO'Id 3ZSHM,`XOZ/t'8d` ,=(QDW)3Z5'2I MO'Id 3'IOAO32I,T

`XOZ/5'•T3`,_(•:;:W)NISVH NOIZVHV3HZJOHWfl'I0A,'XOZ//).VNH0i0001NQZO`HQZO`O5'Z3H.`HH.aH1.`WQ3`SS'IW`Ma`2Ia`A (000T`9)a.I2IM(,NISVH NOV1V3HZJOS3fl'IVA QaNDISaQ, `XOZ//).HW2TOd066

(066`9)3I2IM('1'd` ,=(.33d)2TaIdnwnIO A IVWI2Id 3HZJOH,d3Q,T

`XOZ/5'•13`1=(Z*;W)2IaIJnI5"IO MIVWI2Id 3HZ d0 V32IH,`XOZ/)i.vIOd086d2Ir13Q`Zdv32Iv (086`9)aI2TM

(,(3W NONiaQ (IaWf1SSV)H3VO IddV avN2I1'Iv, `XOZ//).vw2IOd06(O6`9)3.I2TM

('7' Sd` ,=(S2iflOH)3WIZ NONaJ2cI,`XOZ/*1'8d` ,=(Z33d)2IaI3Iu'I0, •`, ATVWI&I3HZ JO H.d3Q,`XOZ/S'ST3` ,=(AHQ'Z,:-d/SNO'I'Ivo)a.v r,Z

`,MO'Id2TaA0, `XOZ/5'•T3`,=(XV(I'Z;:;:a/H'I)2TaIJI2TH'IO A21VWI2Id JO Xfl'IJ,T`XOZ/5' •T3` ,=Z;:rw NI 2IaIJnw'ID MIVWPId 3H.305'32IV, `XOZ/).HW2IOd096

d3WQ`dId3Q`2TJOd`dXfl'Id`Ddv32IH (096`9)31.I2IM(,2IaIJnIwIO AiVWI2Id 3HZ d0 San'IVA QaNDISaQ, `XOZ//)J.vN IOd056

(056`9)3ZI2IMNI MO'IJ, `X0Z/*7' 8d`,=QDWNI MO'IJ, `XOZ/)ZHW2IOd0176

Page 207: Optimal Design and Operation of Wastewater Treatment Plants by

1-7 .21783E-03/,B/0 .0,1 .236415E-01,-3 .52977E-01,4 .15623E-02,2-5 .26710E-02/,C/1 .,2 .,7 .,14 .,21 ./,F/3 .7399E-02/VBOD=1 .0DO 10 I=1,5THETA=F*C(I)*TIME

10

VBOD=VBOD+A(I)*COS(THETA)+B(I)*SIN(THETA)RETURNENDFUNCTION VSNH4(TIME)

CC

DIMENSION A(3),B(3),C(3)DATA A/-0 .0794,0 .0057,-0 .0634/,B/-0 .2996,-0 .059,-0 .0976/DATA C/1 .,2 .,3 ./,F/0 .26179/VSNH4=1 .0DO 10 I=1,3THETA=F*C (I)*TIME

CC

DIMENSION A(5),B(5),C(5)DATA A/0 .0,-6 .96097E-02,- .176173, .14660,-9 .67005E-02/,

1 B/0 .0,2 .60089E-02,- .274343,4 .09673E-02,2 .49002E-02/,2 C/1.,2.,7.,14.,21./,F/3.73999E-02/

C

A(1)=- .154903,B(1)=0 .127113TSS=1 .0DO 10 1=1,5THETA=F*C(I)*TIME

10

TSS=TSS+A(I)*COS(THETA)+B(I)*SIN(THETA)RETURNENDFUNCTION FOW (TIME)

CC

FUNCTION TSS(TIME)

1 95

DIMENSION A(5),B(5),C(5)DATA A/0 .0,5 .41989E-02,- .036769,- .052324, .0618556/,B/0 .0,

1 -1 .3742E-03,2 .57417E-02,- .201479, .155797/,C/1 .,2 .,5 .,7 .,14 ./,2 F/ .0373999/

C A(1)= .00294,B(1)= .0807689C DEETE THE FIRST TERM FOR ONE DAY PERIOD

FOW=1 .0DO 10 I=1,5

10THETA=F*TIME*C (I)FOW=FOW+A(I)*COS(THETA)+B(I)*SIN(THETA)

CCC

RETURNENDFUNCTION VBOD(TIME)

REMOVE THE FIRST TERM FOR ONE DAY PERIODC A(1)=-1 .36395E-01,B(1)=5 .06542E-02

DIMENSION A(5),B(5),C(5)DATA A/0 .0,-8 .15218E-02,-1 .03362E-02,8 .60951E-02,

Page 208: Optimal Design and Operation of Wastewater Treatment Plants by

ENGTH=(AREAPC/WIDTH)*100 .OVE=POFR/24 .5424HI GHT=HEIGHT-'* 100 .XEFFP=BO+B1*FOW+B2*HIGHT+B3*ENGTH+B4*OVE+B5*OVE*OVERE=(SSIN-XEFFP)/SSINIF(RE .GT .0 .20) GO TO 10XEFFP=(1 .-RE)*SSIN

10

RETURNENDSUBROUTINE DIGST1(Q4MT,TACID,BD1,BN1,SI,XNCDI,PVSSD,SRT,OR,

1 OR1,VD,QIIIA,XAR,XPR,XSR,XIR,X2R,CXTPU,XIR,XNR,XNVO1,BDO1,2 NBDO1,XTRDI,IFAGD)

CCC

TOTA ACIDS, BIODEGRADABE SOIDS, NON-BIO-C

DEGRADABE SOIDS, SOUBE SUBSTRATE, NON-VOATIE SOIDS,C

TOTA FOW OF CH4, AND % OF VOATIE SOIDS DESTRUCTIONC

ARE OBTAINED FROM THE DYNAMIC MATHEMATICA MODE OFC

OF ANAEROBIC DIGESTION . EMIPRICA EQUATIONS ARE DEVEOPEDC

FROM THE RESUTS OF DYNAMIC MATHEMATICA MODE .C

REA MSSR1,MSSR2,NBDO1DIMENSION CCO(7),CCS1(7),CCS2(7),0002(7),CC03(7)DATA CCO/35 .91026,173 .12294,318 .82495,18312 .2,31 .731,12691 .33,

1 0 .73391/,CCS1/0 .0,-2 .91355,0 .0,-182 .01,0 .0,-185 .76,0 .0/,

1 96

10

CCC

END

VSNH4=VSNH4+A(I)*COS(THETA)+B(I)*SIN(THETA)RETURN

FUNCTION SVS(S)

SVS IS IN CMS/HRDATA A/ .521753E-07/,B/ .834793E-02/,D/- .103521E-01/,E/ .419438E-02/C=S/1420 .

CC

SVS=SQRT(231 .37/(A+B*C+D*C**2+E*C**3))RETURNENDSUBROUTINE PSD1(XEFFP,ENGTH,POFR,FOW,HEIGHT,AREAPC,SSIN)

DETERMINATION OF EFFUENT SOIDS CONCENTRATION FROM PRIMARYC SEDIMENTATION TANK . EMPIRICA EQUATIONS ARE DEVEOPEDC USING THE SIMUATED DATA FORM THE ADVECTION-DIFFUSIONC EQUATION OF PRIMARY SEDIMENTATION .C

REA ENGTHDATA BO/10 .898/,B1/- .0024733/,B2/ .00861/,B3/ .00849/,

1 B4/ .64623/,B5/- .95693E-03/,WIDTH/14 .36/CC FOW IS IN M**3/HRC OVE : PRIMARY CARIFIER OVERFOW RATE, M**3/M*-*2 DAYC WIDTH IS IN METERS, ENGTH IS IN CMS, AND HEIGHT IS IN METERS .C 1 M**3/M**2/DAY = 24 .5424 GAONS/FT**2/DAYC

Page 209: Optimal Design and Operation of Wastewater Treatment Plants by

6T

QOH;=QOH=ZQOHSS' O;SQOH=QOH047* OtISS,=SS.

0IIIdWSO `V,VGciWIf1WIS 3H1. 9NISf1 QHdO'IHASQ SNOIZVflb3 'IV3PIIdN3

00

(HV.HIU'A`TI1.X`•IZX`ZIZX`TIZXZ`•ITX`ZITX`1ITX`•INX`ZINX`TINX`•IIX`ZIIX`TIIX`•IdX`ZIdX`1IdXT

`•ISX`ZISX`TISX`•IHX`ZIVX`TIVX`J IS`SQOH`ISSfGNOOIS3NI1f102Nf1S(INS

N2If1.H2f•2PIO*() •000+

IZHUO* () ZOOO+Z.HS;=() ZSOO+IHS~,-() T 500+() 000=QSSAd

'O=QSSAd(O'O'b3'VIIIb)3Icurio*(9) •000+

TZ2PI0;-(9) ZOOO+Z.HS* (9) Z SOO+.'HS;% (9) T S00+(9) 000=T QONX

•2I'IOr(S) •000+

TZHgO;=(S) ZOOO+ZJ,HSr(S) ZSOO+.US*(S) T 500+(S) 000=T S

•lrIO*('7)•000+

TZHgOr(+7) ZOOO+ZJ,HS*(t) ZSOO+,2IST(*l) TS00+(*7) 000=TNH

•2I'I0*(•)•000+

TZ2I'IO.."(•)Z000+ZZ2IS-; (•)ZSOO+J,Hs;=(•)TS00+(•)000=TQH

•2I'IO;=(Z)•000+

iZ2I`IO;=(Z) Z000+Z.1S=r(Z) ZSOO+,fIS;=(Z) TS00+(Z)000=QIOV

0'O=N7b (0'0'3Z'1,W*7b)3ITy0V3*(•2I'IO;=(T)•000+

I

Z2I'IO;-(T)ZOOO+Z.xs*(T)ZSOO+.xs*(T)TS00+(T)000)=,Wtb

OZT

(,0' 0=2IaN3?IOIH. WO2Id M0'I32IHQNfl do HEV2I3AH 9NINNf12I,`XZ/)IVNHOJ

OOOT(000T`9)3ZIUM

OTT0ZT OI 09

Z?IS*,2IS=Z1.2IST 2ri0;=ZH'IO=•2I'IOi 2I'IO=,=i wI0=ZwIO

T dANO3 /WIO=fI'IOQA/'*7Z;=VI I I b;=NI S SA=wIO

AVQ •;--;-d/SWINJH.v2I 0NIQV0'I OINV92I0:TH`10

0

AHQ •;-;=W/SWVHD NJ 3.H?I 9NIQVO'I OINV92I0:2IZO

0IHNHA+TOQH=NISSA

TOANX-TOQHN=IHNHA('*1Z;-vI I Ib) /QA=.aS

OTT OZ 09(0'0'b3'VIIIb)3I

OT

(ZHS S'IW / (fnd1.X0;=ANNOO+ZINX));:I G&X=T OANX(ZHSS'IW/(nd,X0*HNN00+2IIX))AI aX=TOQHN

ZHSS'IId/ ((f1d.X0*QHN00+IHSS'IW) *Ia I.X)=TOQHZINX+ld1.X0+2IIX+T 2ISS'IW=Z2IS S'IW2IZX+2ITX+ZISX+2IdX+ IVX=T2ISS'IW

OT 01. 09 (Z'b3'Q9v'IdI)3IO'IdGV/VI I Ib=TZaVd/T9'T17/07dGV H1:VQ

/'8T09T/IdAN00`/iZ'0/ANN03'/0•'0/HNN03'/'0/QHNOOH1.VG/TO•'b-`Z+7'47TOZ-`+7T'•0•9"OZ6T-'9'*1•099'T'099Z`9Z'•SI-/•000t

`/9906'T-`0'0`0'0`O'0'*T6947`0'0`998T9'••T-/Z000•`/0'0`ZS9Z'T`T8•TO'0-`ZS•SZ'T`0'0`0'0`0'0/ZS00 Z

Page 210: Optimal Design and Operation of Wastewater Treatment Plants by

SRTT=SRT`TSSSRT2=SRT*SRTSRT3=SRT*SRT*SRTTXA=-1242397 .+209788 .625*SRT+16574 .043*TSS-249 .2727*SRT3

1 +1200 .9294*SRTTTXP=-1844901 .+450681 .9375*SRT+23641 .293*TSS-436 .2693*SRT3

1 +3756 .8967*SRTTTXI=1214202 .+7254 .95703*SRTTTXS=-95607 .+13635 .207*SRT+2881 .7236*TSS-14 .951*SRT3

1 +58 .41995*SRTTTXN=1220917 .+4413 .207*SRTTIF(SRT .E .10 .) GO TO 10TX1=-15437 .7695+5950 .82031*SRTTX2=-2294 .85156+31 .29755*SRT2+2 .85385*SRTTGO TO 20

10

TX1=0 .0TX2=0 .0

20

T.KT=-8428608 .+1090400 .*SRT+99631 .125*TSS-1052 .4563*SRT31

-42 .86723*BOD2+11677 .16797*SRTTRECV=6 ./(V*THETAH)XAI1=TXA*RECVXPI1=TXP*RECVXS I 1=TXS*RECVXI11=TXI*RECVXNI 1=TXN*RECVXlI1=TX1*RECVX211=TX2*RECVXTI1=TXT`RECVXAI2=XAI1XAI3=XAI1XPI2=XPI1XPI3=XPI1XSI2=XSI1XSI3=XSI1X112=XII1X113=XII2XNI2=XNI1XNI3=XNI1X112=X1I1X113=X1I1X212=X2I1X213=X2I1RETURNENDSUBROUTINE COST(CCOST,OM,VOPC,OURTA,OCRT,BDPBN2,1QO,V,AREAP,BCAP,A3,AGT,QR1,QI,Q4MT,QIIIA,VD,CKWH,CO,2CSD,DHR,HEAD,VOPC1,EFFG)

CC

CCOST

CAPITA COST ($)C

OHRS

: OPERATION MAN-HOUR REQUIREMENT, MAN-HOUR/YEAR,C

XMHRS : MAINTENANCE MAN-HOUR REQUIREMENTS, MAN-HOUR/YEAR,C

TMSU : TOTA MATERIA AND SUPPY COSTS($),C

EER

: EECTRICA ENERGY REQUIRED, KWH/YEAR,

198

Page 211: Optimal Design and Operation of Wastewater Treatment Plants by

C

C

VOPC

: VARIABE OPERATING COSTS($) .C

INDEX1 CONSTRUCTION COST INDEX (UPDATING FROM 1969 TO 1984)C

INDEX2 : MATERIA AND SUPPY COSTS INDEX( UPDATING FROMC

1969 TO 1984CCC

COST FUNCTIONS FOR UNIT PROCESSESC

DIMENSION P1(11),P2(11),P3(11),P4(11),P5(11),U1(11),U2(11),1 U3(11),U4(11),U5(11),R1(11),R2(11),R3(11),R4(11),R5(11),S1(11),2 S2(11),S3(11),S4(11),S5(11),T1(11),T2(11),T3(11),T4(11),T5(11),3 CCOST(11),X(11),OHRS(11),XMHRS(11),TOMMH(11),TMSU(11),EER(11),4 EERMS(11),EER1(11),OM(11)REA INDEX1, INDEX2

C .C

DATA FOR COST FUNCTIONSC

DATA Pl/3 .259716,3 .716354,2 .41438,4 .14884,0 .0,3 .716354,7 .679634,13 .725902,3 .481553,-1 .4455,0 .0/,P2/ .619151, .389861, .175682, .713634,20 .0, .389861,-1 .949689, .39769, .377485,2 .33858,0 .0/,P3/0 .0, .08456,3 .084742,- .052596,0 .0, .08456, .402561, .075742, .093349,- .382633,40 .0/,P4/0 .0,- .004718,- .00267, .0147487,0 .0,- .004718,- .018211,5- .001977,- .006222, .025888,0 .0/,P5/0 .0,0 .0,0 .0,0 .0,0 .0,0 .0,0 .0,6- .000296,0 .0,0 .0,0 .0/

DATA U1/6 .39872,5 .846565,0 .0,6 .900586,0 .0,5 .846565,9 .12925,1 5 .846565,6 .097269,4 .36501,0 .0/,U2/ .230956, .258413,0 .0, .323725,2 0 .0,0 .0,-1 .816736, .254813, .253066, .7038535,0 .0/,U3/ .164959,3 .113703,0 .0, .059093,0 .0, .113703, .373282, .113703,- .193659,4 .0422545,0 .0/,U4/- .014601,- .010942,0 .0,- .004926,0 .0,- .010942,5 - .017429,- .010942, .078201,- .0019301,0 .0/,U5/0 .0,0 .0,0 .0,0 .0,0 .0,6 0 .0,0 .0,0 .0,- .00668,0 .0,0 .0/

DATA R1/5 .846098,5 .273419,0 .0,6 .169937,0 .0,5 .273419,8 .566752,1 5 .273419,5 .911541,1 .83957,0 .0/,R2/ .206513, .228329,0 .0, .294853,2 0 .0, .228329,-1 .768137, .228329,- .013158,1 .683691,0 .0/,R3/ .068842,3 .122646,0 .0, .175999,0 .0, .122648, .363173, .122646, .076643,- .231481,4 0 .0/,R4/ .023824,- .011672,0 .0,- .040947,0 .0,- .011672,- .01662,5 - .011672,0 .0, .014133,0 .0/,R5/- .00441,0 .0,0 .0, .0033,0 .0,0 .0,0 .0,6 0 .0,0 .0,0 .0,0 .0/DATA S1/7 .235657,5 .669881,0 .0,0 .0,0 .0,5 .669881,8 .702803,5 .669881,

1 5 .051743,31 .17094, .62138/,S2/ .399935, .750799,0 .0,0 .0,0 .0, .750799,2 - 1 .182711, .750999, .30161,-15 .22357, .482047/,S3/- .224979,0 .0,0 .0,3 0 .0,0 .0,0 .0, .282691,0 .0, .197183,3 .07994,0 .0/,S4/ .110099,0 .0,0 .0,4 0 .0,0 .0,0 .0,- .013672,0 .0,- .017962,- .195488,0 .0/,55/- .011026,0 .0,5 0 .0,0 .0,0 .0,0 .0,0 .0,0 .0,0 .0,0 .0,0 .0/DATA Tl/6 .30864,11 .0736,0 .0,0 .0,-12 .1285,5 .97902,12 .43648,

1 -12 .5085,0 .0,0 .0,0 .0/,T2/ .234529,-1 .25742,0 .0,0 .0,10 .98686,2 .377519,-2 .089456,6 .72116,0 .0,0 .0,0 .0/,T3/- .0358436, .168361,3 0 .0,0 .0,-2 .028497, .011379, .28,- .74406,0 .0,0 .0,0 .0/,4 T4/ .008712,- .0046671,0 .0,0 .0, .171772,- .000841,- .0083527,5 .0305456,0 .0,0 .0,0 .0/,T5/0 .0,0 .0,0 .0,0 .0,- .0051743,0 .0,0 .0,6 0 .0,0 .0,0 .0,0 .0/

X(1) : FOW THOROUGH THE SCREEN AND GRIT CHAMBER, MGD

1 99

Page 212: Optimal Design and Operation of Wastewater Treatment Plants by

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((i7;:*(I)X).(I)52I+T(•;:;:(I)X)*(I)'7tI+(I)Xm(I)X*(I)•tr+(I)X*(I)ZH+(I)TH)dX3=(I)SHHWX

((47*;:(I)X)*(I)Sn+T(•*;:(I)X)v(I)17n+(I)Xr(I)X;:(I)•n+(I)X;:(I)Zn+(I)Tn)dX3=(I)SHHO

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iZZ Z O. 00

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(9' •5+7/' oooi''7z;:vJIno)no1v=(5)X(dv3H) oo'Iv=(t)X

(z.SNO3;:A)oo'IU=(•) X(IZSN03;=dva1v) Oo'Iv=(Z) X

'0001/*!I•'S•=Z.SN03'OOOT/6•9'OT=T,SN03

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Page 213: Optimal Design and Operation of Wastewater Treatment Plants by

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560 09HM?I3*C(47x:x:(I)X)x:(I)SZ+ T

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OTT9zoilO9

ZX3QNI*(()X*()Xx:99TZ0'+()X*T4786T'+•Z9T•S'9)dX3=()IISWs2IHa*(()SHHWX+()S?IHO)= ()HWWO.

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•zczoil09

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OTT 01 09 (TT'b3'I)3I2IHth((I)SZIHNX+( I) S2IHO) =(I) HWWO.

0'0=(I)HWWO.'0=(I)SHHWX0'0=(I)SHHOST

OT O. 09ST oZ 09 (Ti'b3'I)3ISi 0. 09 (5 'b3'I)3I

(I)2i33+(Ii)IISW,+(I)HWWo = (I)Wo(47'b3'I)3I((I)2I33+(I)IISW,+(I)HWWO.)=(I)WO

((I)IISW,+(I)HWWO.)=(I)Wo (S'b3'I)3I56(I) SW2i33+(i) 2i33=(I) ni33

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T

56 oZ 09 (i'Z0'I)3IHM?I3-.AdMNA=( I) 2133

(333dx'OSSx009•x:'*~Z=,=8~7')/C'S9• •*l'~:Qf73II;=•0'Ta:~l'Z9~:9030'T;:T?Ib)=~idM?I~I

T093

2IA/HMX:&cIMXA33

•8'0=333d809 01. 09

47 '0=333d99`8`9(90'0T-nrb)3I47

090.00'0=333dU

47`47 `Z(4741'T-THb)3IIb=THb (OT'b3'I)dI0•

Page 214: Optimal Design and Operation of Wastewater Treatment Plants by

TMSU(I)=0 .010

CONTINUECCOST(5)=0 .0CCOST(11)=0 .0OM(11) =0 .0OM(3)=O.0X1=AOG(QO*CONST3)

CC

CAPITA COST FOR ADMINISTRATION AND ABORATORY FACIITIES, $1000C

CCOSTA=EXP(3 .55928+ .35094 7X1+ .0830 6X1*XI - .009318*Xl*X1*X1)1 1.1000 .

C

CAND : COST OF TOTA AND REQUIRED .C

CO

: COST OF AND/ACRECAND=EXP(2 .322414+ .1879797`X1+ .04151*X1*X1+ .0023517*X1*X1-*X1)

1 -COTCST1=0 .0DO 200 I=1,NC1

200

TCST1=TCST1+CCOST(I)TCST=TCST1/1000 .

CC

TCST : TOTA CONSTRUCTION COST, $1000X2=AOG(TCST)

CC ECOST : ENGINEERING COST

ECOST=EXP( .6654462+ .44256*X2+ .023343*X2*X2- .0001259-X2*X2*X2)1*1000 .

CC

TCOST TOTA CONSTRUCTION, ENGINEERING AND AND COSTSC

TCOST : A CONSTRUCTION COSTS+ECOST+CANDC

ADMNC EGA, FISCA AND ADMINISTRATION COSTSC

CSUDG : COST OF SUDGE DISPOSAC

TCOST=TCST1+ECOST+CANDTCOST1=TCOST/1000 .X3=AOG(TCOST1)ADMNC=EXP(-1 .23038+ .313308*X3+ .0691976*X3*X3- .004646*X3*X3*X3)1*1000 .

C

ENERGY FROM GAS, BTU/FT**3C

35 .3147

CONVERSION FROM M**3 TO FT**3C

2 .9037* E-04 : CONVERSION FROM HP TO KWH (1 ./550*7 .48*0 .83)C

0 .83 IS THE EFFICIENCYWRITE(6,1000)

1000 FORMAT(//10X,'CAPITA COSTS ($)')WRITE(6,1010) CCOST(1),CCOST(2),000ST(3),CCOST(4),CCOST(6),1000ST(7),000ST(8),CCOST(9),CCOST(10)

1010 FORMAT(/5X,'PRIMARY TREATMENT(SCREENING, GRIT REMOVA, AND',$' FOW MEASUREMENTS)=',E15 .5/5X,$'PRIMARY CARIFIER=',48X,E15 .5/5X,'AERATION TANK=',52X,E15 .5/5X,$'DIFFUSERS=',56X,E15 .5/5X,'SECONDARY CARIFIER=',46X,E15 .5/5X,$'DIGESTER=',57X,E15 .5/5X,'THICKENER=',56X,E15 .5/5X,$'RECIRCUATION AND MIXING PUMPS=',35X,E15 .5/5X,$'SUDGE PUMPS=',53X,E15 .5)

202

Page 215: Optimal Design and Operation of Wastewater Treatment Plants by

WRITE(6,1020)1020 FORMAT(//10X, 'OPERATION AND MAINTENANCE COSTS($/YR)')

WRITE(6,1030) OM(1),OM(2),OM(4),OM(5),OM(6),OM(7),OM(8),$OM(9),OM(10)

1030 FORMAT(/5X,'PRIMARY TREATMENT=',48X,E15 .5/5X,$'PRIMARY CARIFIER=',48X,E15 .5/5X,$'AERATION (EXCUDING ENERGY COST)=',33X,E15 .5/5X,$'DIFFUERS=',57X,E15 .5/5X,'SECONDARY CARIFIER=',46X,E15 .5/5X,$'DIGESTER=',57X,E15 .5/5X,'THICKENER=',56X,E15 .5/5X,$'RECIRCUATION AND INTERMIDIATE PUMPING=',27X,E15 .5/5X,$'SUDGE PUMPING=',51X,E15 .5)CQCH4=(Q4MT*35 .3147%`550 . `2 .9307 *1 .E-04*CKWH)*EFFG`CONST4IF(QIIIA .EQ .0 .0) QIIIA=1 .35CSUDG=(QIIIA%BDPBN2*CSD`CONST4/CONST5)VOPC=EER(5)-CQCH4VOPC1=CSUDGWRITE(6,1040)

1040 FORMAT(//10X, 'VARIABE OPERATING COSTS($/YR)')WRITE(6,1050) VOPC,CSUDG,CQCH4

1050 FORMAT(/5X,'ENERGY COST (AERATION)=',43X,E15 .5/5X,$'SUDGE DISPOSA COST=',45X,E15 .5/5X,$'REVENUE FROM METHANE GAS=',41X,E15 .5)TOTC=0 .0DO 11 I=1,NC1

11

TOTC=TOTC+CCOST(I)+OM(I)TOTAC=TOTC+VOPC+VOPC1WRITE(6,1060) TOTAC

1060 FORMAT(///5X,'TOTA COSTS/YR=',51X,E15 .5//////////)RETURNENDSUBROUTINE OPTIM5(PARO,PAR,PARU,PADJ,C,ER,ERM,ND,ND2,NE,M,

1 MM,MITER,IN,NN)C . . THIS SUBROUTINE IS THE MAIN CA TO THE OPTIMIZATION PROGRAMS .C . . THE PARAMETERS IN THE CA TO OPTIM AREC

PARO = OD VAUE OF THE PARMETERS ESTIMATESC

PAR = OWER CONSTRAINTS ON THE PARAMETERSC

PARU = UPPER CONSTRAINTS ON THE PARAMETERSC

PADJ = WEIGHTING FACTOR FOR EACH ERROR FUNCTIONC

PAR1 = NEW VAUE OF THE PARAMETER ESTIMATESC

CC = INFUENCE COEFFICIENT ARRAYC

ER = ARRAY CONTAINING MODE RESIDUAS AT A OBSERVATIONSC

ERM = UNWEIGHTED MODE SUM OF SQUARES ERROR, BY ERROR FUNCTIONC

ND = NUMBER OF PARAMETERS TO BE ESTIMATEDC

ND2 = ND*2C

ND5 = 5 *NDC

ND5P1 = ND5+1C

NE = NUMBER OF ERROR FUNCTIONSC

M

= NUMBER OF OBSERVATIONSC

MM = MAXIMUM NUMBER OF OBSERVATIONSC

MITER= MODE ITERATION NUMBERC

ITERM= NUMBER OF ITERATIONS AOWED FOR THE QUADRATIC ANDC

PATTERN SEARCH ROUTINESC

IN = METHOD OF SEARCH 1 = INEAR REGRESSION (NO CONSTRAINTS)

203

Page 216: Optimal Design and Operation of Wastewater Treatment Plants by

C

2 = PATTERN SEARCH, AND 3 = QUADRATIC PROGRAMINGC

NN = TYPE OF WEIGHTING MATRIX : 1 = IDENTITY MATRIXC

2 = INVERSE OF COVARIANCE MATRIX OF ERRORSC . . THE FOOWING ARRAYS ARE USED FOR THE PARAMETER CORREATIONC SUBROUTINE AND ARE DIMENSIONED IN THIS SUBROUTINE IN ORDERC TO AVOID DIMENSIONS IN THE CAING PROGRAMC ARRAYS COVAR, HESS, AND CORR ARE DIMENSIONED (ND,ND,NE)C ARRAYS INDEX(NE),FACTOR(NE)C ARRAY (ND) (USED TWICE, IN THE OPTIMIZATION AND CORREATIONC PGMS) . THE FOOWING GROUP OF ARRAYS USE DYNAMIC AOCATIONC ARRAYS PARO,PAR,PADU,AND PARJ ARE DIMENSIONED IN THEC MAIN PROGRAM AT ND

DIMENSION PARO(ND),PAR(ND),PARU(ND),PADJ(ND)C . . ARRAY C IS THE INFUENCE COEFFICIENT ARRAY AND IS DIMENSIONEDC . . NE BY ND BY MM IN THE MAIN PGM

DIMENSION C(NE,ND,MM)C . . ARRAY ER IS THE ERROR ARRAY AND IS DIMENSIONED MM BY NE IN THE MAINC

PGM . ERM IS THE UNWEIGHTED MODE ERROR .DIMENSION ER(MM,NE),ERM(NE)

C . . THE NEXT GROUP OF ARRAYS MUST BE DIMENSIONED USING NUMERIC CONSTANTSC THOSE ARRAYS ARE USED BY THE OPTIMIZATION PROGRAMSC . . ARRAYS PAR1, CQD,DD, AND BB MUST BE DIMENSIONED ND

DIMENSION PAR1(5),CQD(5),DD(5),(5),BB(5),IPARM(5)C . . ARRAYS CQC AND CC MUST BE DIMENIONED ND BY ND

DIMENSION CQC(5,5),CC(5,5)C . . ARRAY AA MUST BE DIMENSIONED ND BY ND2

DIMENSION AA(5,10)C . . ARRAYS QQ AND QA MUST BE DIMENIONED AT NE BY NE

DIMENSION QQ(3,3),QA(3,3)C . . ARRAY D MUST BE DIMENSIONED NE BY MM

DIMENSION D(3,11)C . . ARRAY WA6,IWA7 AND WA9 MUST BE DIMENSIONED ND2

DIMENSION WA6(10),IWA7(10),WA9(10)C . . ARRAY IWA8 MUST BE DIMENSIONED ND5 (ND5=5*ND)

DIMENSION IWA8(25)C . . ARRAY WA2,WA3,WA4 AND WA5 MUST BE DIMENSIONED ND5P1 (ND5P1=5*ND+1)

DIMENSION WA2(26),WA3(26),WA4(26),WA5(26)C . . ARRAY WA1 MUST BE DIMENSIONED ND2 BY ND5P1

DIMENSION WA1(10,26)C . . ARRAYS COVAR, HESS, COR MUST BE DIMENSIONED ND BY ND BY NE

DIMENSION HESS(5,5,3),COVAR(5,5,3),COR(5,5,3)C . . ARRAYS INDEX AND FACTOR MUST BE DIMENSIONED NE

DIMENSION FACTOR(3),INDEX(3)C . . ARRAYS CENTER AND EROBFU MUST BE DIMENSIONED ND+1

DIMENSION CENTER(6),EROBFU(6)C . . ARRAY PARMS MUST BE DIMENSION ND BY ND+l

DIMENSION PARMS(5,6)COMMON /DBUG/ IDEBGCOMMON /IOPT/NROPT,NWOPTCOMMON /IOSRC/NRISRC,NWISRCCOMMON /IOCOR/NRICOR,NWICRCOMMON /IOPRT/NRIPRT,NWIPRT

204

Page 217: Optimal Design and Operation of Wastewater Treatment Plants by

DATA JUMP /0/

C . . DETECT THE FIRST CA TO THE SUBROUTINE AND WRITE A HEADINGIF (JUMP) 10,10,160

10 JUMP=1NROPT=5NWOPT=6NWISRC=6NRISRC=5NWIPRC=6NRIPRC=5NWICOR=6NRICOR=5NREAD=5NWRITE=6WRITE(NWRITE,1000)

1000 FORMAT('lINFUENCE COEFFICIENT OPTIMIZATION PROCEDURE BEGINNING')IF(IN .GT .O .AND .IN .T .4) GOTO 20WRITE(NWRITE,1010) IN

1010 FORMAT(' *** ERROR **iy METHOD CODE OUT OF RANGE *** ERROR1/, 'IN=',I5,/,' EXECUTION TERMINATING ')STOP 10

20

IF(NN .GT .O .AND .NN .T .3) GOTO 30WRITE(NWRITE,1020) NN

1020 FORMAT(' *** ERROR *** WEIGHTING CODE OUT OF RANGE "* ERROR ***'1/,' NN=',15,/,' EXECUTION TERMINATING')STOP 20

C . . WRITE OUT THE HEADINGS30

GOTO(40,50,60),IN40

WRITE(NWRITE,1030)1030 FORMAT(' NORMA EQUATION SOUTION SEECTED (NO CONSTRAINTS)')

GOTO 7050

WRITE(NWRITE,1040)1040 FORMAT(' CONSTRAINED PATTERN SEARCH METHOD SEECTED')

GOTO 7060

WRITE(NWRITE,1050)1050 FORMAT(' QUADRATIC PROGRAMING (WOF AGORITHM) SEECETED')70

GOTO (80,90),NN80

WRITE(NWRITE,1060)1060 FORMAT(' IDENTITY ERROR WEIGHTING MATRIX SEECTED')

GOTO 10090

WRITE(NWRITE,1070)1070 FORMAT('OINVERSE OF THE ERROR COVARIANCE MATRIX SEECTED' .)C . . CACUATE THE MAXIMUM NUMBER OF ITERATIONS FOR THE INFUENCEC OPTIMIZATION100 ITERM=20C . . IF THE PATTERN SERARCH IS SEECTED RECACUTATE ITERM

IF(IN .EQ .2) ITERM=ND*150C . . WRITE OUT THE REST OF THE SUMMARY

WRITE(NWRITE,1080) ND,NE,M,ITERM1080 FORMAT(///,' NUMBER OF PARAMETERS=

',I5,1/,

' 'NUMBER OF ERROR FUNCTIONS

',I5,2/,

NUMBER OF DATA POINTS=

',I5,

205

Page 218: Optimal Design and Operation of Wastewater Treatment Plants by

3/,

' MAXIMUM NUMBER OF ITERATIONS',4/,

' FOR THE INFUENCE OPTIMIZATION= ',15,//)C . . SKIP CHECKING FOR CONSTRAINTS IF THE METHOD CODE = 1C (UNCONSTRAINED INEAR REGRESSION)

IF(IN .EQ .1) GOTO 140C . . CHECK TO MAKE SURE THAT THE OWER CONTRAINTS ARE ESS THANC THE UPPER CONSTRAINTS ; OTHERWISE AN INFINITE OOP WI BEC GENERATED IN THE OPTIMIZATION ROUTINES

DO 110 I=1,NDIF(PAR(I) .GE .PARU(I)) GOTO 120

110 CONTINUEGOTO 124

120

WRITE(NWRITE,1090) PAR(I), I, PARU(I)1090 FORMAT(///,' -`*`** ERROR

THE OWER CONTRAINT(',1E17 .6,' ) FOR PARMATER NO .',I2,' IS GREATER THAN OR EQUA TO',2' THE UPPER CONSTRAINT(',E17 .6,' )')

C . .

CHECK TO MAKE SURE THE INITIA PARAMETER SET IS FEASIBE124

DO 130 I=1,NDIF(PARO(I)-PAR(I)) 127,125,125

125 IF(PARO(I)-PARU(I)) 130,130,127127

WRITE(6,1100) I,PAR(I),PARU(I),PARO(I)1100 FORMAT(' **** ERROR

PARAMETER NO .',I3,' IS EITHER ESS'1' THAN THE OWER CONSTRAINT (',E17 .6,')',/,' OR GREATER THAN THE2,' UPPER CONSTRAINT(',E17 .6,')',/,' PARMETER=',E17 .6)STOP 50

130 CONTINUEWRITE(6,1102)

1102 FORMAT(//,1'

CONSTRAINTS SUMMARY',/,2' PARAMETER NUMBER OWER IMIT STARTING VAUE UPPER IMIT',3/,1X,63('-'))DO 128 I=1,ND

128

WRITE(6,1103) I,PAR(I),PARO(I),PARU(I)1103 FORMAT(8X,I2,3(3X,E12 .5))C . . THIS CA TO CORDUM IS FOR DYNAMIC ARRAY AOCATION140 CA CORDUM(ERM,C,HESS,COVAR,COR,CC,FACTOR,INDEX,,IPARM,

1ND,NE,M,MM)C . . THE PAR1 ARRAY REQUIRES INITIIZATION AND IS CHECKED IN SUBROUTINEC WOFE

DO 150 I=1,ND150

PAR1(I)=PARO(I)ND5=ND2+ND2+NDND5P1=ND5+1NDP1=ND+1

160 CONTINUEC . . WRITE OUT THE MODE ERROR

SUM =0 .DO 170 I=1,NE

170 SUM=SUM+ERM(I)WRITE(NWRITE,1110) MITER,((I,ERM(I)),I=1,NE)

1110 FORMAT('OUNWEIGHTED MODE SUM OF SQUARE ERRORS FOR MODE ITERAT',1' ION NUMBER ',I2,/,'OERROR FUNCTION',7X,'ERROR',210(/,7X,I2,6X,E12 .5))

206

Page 219: Optimal Design and Operation of Wastewater Treatment Plants by

WRITE(NWRITE,1120) SUM1120 FORMAT(' TOTA ERROR= ',E12 .5)

CA TRANSF(C,ER,PARO,PAR,PARU,PADJ,QQ,QA,,D,CQC,CQD,AA,BB,CC,1DD,EE,NE,ND,ND2,M,MM,IN,NN)GO TO (180,190,200),IN

180

CA REGRE(CC,DD,EE,PAR1,,CQC,ND)GO TO 210

C . . THIS ENTRY IS TO THE PATTERN SEARCH BECAUSE WOFE FAISC . . THE NUMBER OF ITERATIONS MUST BE INCREASED AND RESET185 ITERMS=ITERM

ITERM=200`ND190

CA PATSRC(PAR,PARU,PARO,PAR1,PADJ,C,ER,QA,FACTOR,ND,NDP1,NE,MM,1ITERM,M,PARMS,EROBFU,CENTER,EE)IF( IFAUT .GT .0) ITERM=ITERMSGO TO 210

200

CA WOFE(PAR,PAR1,AA,BB,CC,DD,EE,WA1,WA2,WA3,WA4,WA5,WA6,IWA7,1 IWA8,WA9,ND,ND,ND2,ND5,ND5PI,ITERM,IDEBG,IFAUT)

C . . CHECK FOR NON-CONVERGENCE OF THE WOFE AGORITHM AND CHANGEC TO PATTERN SEARCH FOR THIS ITERATION ONY IF UNCONVERGED

DO 220 I=1,ND220

PARO(I)=PAR1(I)RETURNENDSUBROUTINE CORDUM(ER,C,HESS,COVAR,COR,ARED,FACTOR,INDEX,,IPARM,

1ND,NE,M,MM)C . . THIS ENTRY IS USED TO SET-UP THE DYNAMIC DIMENSION AOCATIONS

DIMENSION COVAR(ND,ND,NE),HESS(ND,ND,NE),COR(ND,ND,NE),(ND),1ARED(ND,ND),IPARM(ND),INDEX(NE),FACTOR(NE),ER(NE),C(NE,ND,MM)COMMON /DBUG/ IDEBUGCOMMON /IOCOR/NREAD,NWRITERETURNENTRY CORRE(ER,C,ND,NE,M,MM)

C . . CACUATE HESSIAN MATRIX OF THE ESTIMATES OF PARAMETERS FOR EACHC

CONCENTRATION PROFIE FUNCTIONIFIN=ONEO=NE

5

DO 200 II=1,NEOINDEX(II)=0FACTOR(II)=0 .DO 10 =1,ND()=0DO 10 K=1,NDCOR(K,,II)=0 .COVAR(K,,II)=0 .

10

HESS(K,,II)=0 .0

207

IF( IFAUT .GT .0) GOTO 185210 WRITE(NWRITE,1130) (I,I=1,ND)

1130

WRITE(NWRITE,1140)WRITE(NWRITE,1150)

(PAR1(I),I=1,ND)EE

FORMAT(/,' NEW PARAMETER ESTIMATES',/,10(5X,I2,5X),/)1140 FORMAT(1X,8E12 .5)1150 FORMAT(/,' INEARIZED OBJECTIVE VAUE=',E13 .5,/)C . . REPACE THE NEW PARAMETERS IN THE OD PARAMETER ARRAY

Page 220: Optimal Design and Operation of Wastewater Treatment Plants by

DO 20 J=1,MDO 20 K=1,NDDO 20 =K,ND

20

HESS(K,,II)=HESS(K,,II)+C(II,K,J)*C(II,,J)DO 30 I=2,NDI1=I-1DO 30 J=1,I1

30

HESS(I,J,II)=HESS(J,I,II)IF(IDEBUG) 60,60,40

C . . WRITE OUT THE HESSIAN MATRIX IF IDEBUG IS TURNED ONC . . FIRST INITIAIZE THE ARRAY CONTAINING THE PARAMETER NUMBERS40

DO 50 I=1,ND50

IPARM(I)=IWRITE(NWRITE,1000) II

1000 FORMAT(///,' HESSIAN MATRIX FOR ERROR PROFIE NO ',I2,///)CA PRINTA(HESS,IPARM,II,ND,ND,NE)

C . . CACUATE COVARIANCE AND CORREATION MATRIX OF THE ESTIMATES OFC

PARAMETERS FOR EACH CONCENTRATION PROFIE FUNCTION60

DO 70 I=1,ND70

COVAR(I,I,II)=1 .0CA RNKRED(HESS,ARED,,IPARM,ND,NE,II,IRANK)CA UPPDC(ARED,,IRANK,ND,ND,INDEX(II))

C . . CHECK FOR SINGUARITY AND END PROCESSING IF SINGUARIF(INDEX(II)-1) 90,80,80

C . . SINGUAR HESSIAN MATRIX80

WRITE(NWRITE,1010) II1010 FORMAT('OTHE HESSIAN MATRIX FOR CONCENTRATION PROFIE ',I2,

1' IS SINGUAR',/,' PROCESSING STOPPING FOR THIS PROFIE')C . . WRITE OUT THE HESSIAN MATRIX IF IDEBUG IS NOT TURNED ON

IF(IDEBUG)200,85,20085

WRITE(NWRITE,1000) IICA PRINTA(HESS,IPARM,II,IRANK,ND,NE)GOTO 200

90

DO 100 J=1,IRANK100

CA UPPSB(ARED,COVAR(1,J,II),,IRANK,ND,ND)C . . NOTE THAT THE NE/NEO IN THE NEXT INE KEEPS THE DATA POINT COUNTC CORRECT FOR THE COMPOSITE ANAYSIS WHICH FOOWS ATER .

FACTOR(II)=ER(II)/((NE/NEO)*M-ND)DO 110 I=1,NDDO 110 J=1,ND

110

COVAR(J,I,II)=FACTOR(II)*COVAR(J,I,II)WRITE(NWRITE,1020) II

1020 FORMAT(///,' THE COVARIANCE MATRIX OF THE ESTIMATES OF PARAMETERS'1,' FOR CONCENTRATION PROFIE',I3,/)CA PRINTA(COVAR,IPARM,II,IRANK,ND,NE)

C . . CACUATE CORREATION MATRIX OF THE ESTIMATES OF PARAMETERS FORC

EACH CONCENTRATION PROFIE FUNCTIONDO 120 I=1,IRANKDO 120 J=1,IRANKTERM=COVAR(I,I,II)*COVAR(J,J,II)

120

COR(I,J,II)=COVAR(I,J,II)/(SQRT(ABS(TERM)))WRITE(NWRITE,1030) II

1030 FORMAT(///,' THE CORREATION MATRIX OF THE ESTIMATES OF',

208

Page 221: Optimal Design and Operation of Wastewater Treatment Plants by

1' PARAMETERS FOR CONCENTRATION PROFIE',I3,/)CA PRINTA(COR,IPARM,II,IRANK,ND,NE)

200 CONTINUEIF( IFIN .GT .O .OR .NE .EQ . 1 ) GOTO 240IF IN=1

C . . ADD UP THE INFUENCE COEFFICIENT MATRIX BY ERROR FUNCTIONSC AND THE ERROR VECTOR TO CACUATE A COMPOSITE CORREATIONC AND COVARIANCE MATRIX

DO 220 J=1,NDDO 220 K=1,MSUM=O .DO 210 I=1,NE

210

SUM=SUM+C(I,J,K)220

C(1,J,K)=SUM/NEC . . ADD UP THE ERROR VECTOR

DO 230 I=2,NE230

ER(1)=ER(1)+ER(I)C . . NOW SET THE DO OOP COUNTER FOR ERROR FUNCTIONS TO 1C NEO IS ASO USED IN THE FACTOR CACUATIONS .

NEO=1C . . WRITE OUT A HEADER TO INDICATE THAT THE COMPOSITE ERROR FUNCTIONC IS BEING EVAUATED

WRITE(NWRITE,1040)1040 FORMAT(//,' **-.**************COMPOSITE ANAYSIS BEGINNING*******, .'

GOTO 5240 CONTINUE

RETURNENDSUBROUTINE COVARI(X,Y,Q,M)DIMENSION X(M),Y(M)SUMX=0 .0SUMY=0 .0K=0DO 100 I=1,MIF(X(I) .EQ .0 .0 .OR .Y(I) .EQ .0 .0) GO TO 100SUMX=SUMX+X (I)SUMY=SUMY+Y (I)K=K+1

100 CONTINUESUMX=SUMX/KSUMY=SUMY/KQ=0 .0DO 200 I=1,MIF(X(I) .EQ .O .O .OR .Y(I) .EQ .0 .0) GO TO 200Q=Q+(X(I)-SUMX)*(Y(I)-SUMY)

200 CONTINUEQ=Q/KRETURNENDFUNCTION ERRFNK(ER,C,QA,PARO,PAR1,FAC,ND,NE,MM,NPOINT)

C . . THIS FUNCTION EVAUATES THE INFUENCE COEFFICIENT MATRIXC FOR THE PATTERN SEARCH ROUTINE .

209

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DIMENSION ER(MM,NE),C(NE,ND,MM),PARO(ND),PAR1(ND),FAC(NE),1QA(NE,NE)

C . . INITIAIZE THE ERRFNK AND FAC ARRAYS TO ZEROERRFNK=O .

C . . CACUATE THE REATIONSHIP "E X INV COV X E TRANSPOSE"C FOR EACH ERROR POINT . THE TOTA IS SUMMED USING THEC FUNCTION NAME

DO 40 K=1,NPOINTC . . FIRST CACUATE THE ERROR VECTOR AT EACH OBSERVATION

DO 25 I=1,NESUM=O .DO 20 J=1,ND

20

SUM=SUM+(PAR1(J)-PARO(J))*C(I,J,K)25

FAC(I)=ER(K,I)+SUMC . . NEXT MUTIPY THE ERROR AND INVERSE COVARIANCE MATRICESC USING THE INTERMEDIATE VARIABE SUM FOR STORAGE

DO 40 I=1,NESUM=O .DO 30 J=1,NE

30

SUM=SUM+QA(J,I)*FAC(J)40

ERRFNK=ERRFNK+SQRT(SUM*FAC(I))RETURNENDSUBROUTINE REGRE(CC,DD,EE,P1,,CQ,ND)DIMENSION CC(ND,ND),DD(ND),P1(ND),(ND),CQ(ND,ND),TEM1(1),TEM2(1)DO 100 I=1,NDP1(I)=DD(I)DO 100 J=1,ND

100 CQ(J,I)=CC(J,I)CA UPPDC(CQ,,ND,ND,ND,INDEX)CA UPPSB(CQ,P1,,ND,ND,ND)CA MUTIQ(P1,CC,P1,TEM1,1,ND,ND,1)CA MUTIP(P1,DD,TEM2,1,ND,1,1,ND,1)EE=EE+TEM1(1)-2 .0*TEM2(1)RETURNENDSUBROUTINE UPPDC(A,,N,ND1,ND2,INDEX)DIMENSION A(ND2,ND1),(ND1)

C**C** DECOMPOSITION WITH PARTIA PIVOTING A=UC**

DO 50 J=1,NJ1=J-1AJJ=0 .0DO 30 1=1,NI1=MINO(I-1,J1)AIJ=A(I,J)IF(I1 .E .0) GO TO 15DO 10 K=1,I1

10 AIJ=AIJ-A(I,K)%cA(K,J)C**

15 IF(I .GE .J) GO TO 20A(I,J)=AIJ/A(I,I)

210

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GO TO 3020 A(I,J)=AIJ

IF(AJJ .GE .ABS(AIJ)) GO TO 30M=IAJJ=ABS(AIJ)

30 CONTINUEC**

IF(AJJ .EQ .0 .0) GO TO 55(J)=MIF(M .EQ .J) GO TO 50DO 40 I=1,NAIJ=A(M,I)A(M,I)=A(J,I)

40

A(J,I)=AIJ50

CONTINUEC . . SUCCESSFU CA . RETURN INDEX CODE = 0 TO

INDEX=ORETURN

C . . SINGUAR MATRIX . RETURN INDEX CODE = 1 TO55

INDEX=1RETURNENDSUBROUTINE UPPSB(A,B,,N,ND1,ND2)DIMENSION A(ND2,ND1),B(ND1),(ND1)

C**C** AX=B : UX=BC** FORWARD SUBSTITUTION Y=BC**

DO 70 I=1,NI1=I-1M= (I)BI=B(M)B(M)=B(I)IF(I1 .E .0) GO TO 70DO 60 K=1,I1

60 BI=BI-A(I,K)*B(K)70 B(I)=BI/A(I,I)

C**C** BACKWARD SUBSTITUTION UX=YC**

N1=N-1DO 90 IN=1,N1I=N-INI1=I+1BI=B(I)DO 80 K=I1,N

80 BI=BI-A(I,K)*B(K)90 B(I)=BI

RETURNENDSUBROUTINE MUTIP(A,B,C,N,M,,NA,NB,NC)DIMENSION A(NA,M),B(NB,),C(NC,)DO 100 I=1,N

211

INIDCATE SUCCESS

INDICATE SINGUARITY

Page 224: Optimal Design and Operation of Wastewater Treatment Plants by

DO 100 J=1,C(I,J)=0 .0DO 100 K=1,M

100 C(I,J)=C(I,J)+A(I,K)*B(K,J)RETURNENDSUBROUTINE MUTIQ(A,B,C,D,MA,MB,MC,MD)DIMENSION A(MB,MA),B(MB,MC),C(MC,MD),D(MA,MD)DO 100 I=1,MADO 100 J=1,MDD(I,J)=0 .0DO 100 K=1,MBDO 100 N=1,MC

100 D(I,J)=D(I,J)+A(K,I)-B(K,N) .C(N,J)RETURNENDSUBROUTINE PATSRC(PAR,PARU,PARO,PAR1,W,C,ER,QA,FAC,ND,NDP1,

1NE,MM,ITERM,NPOINT,PARMS,EROBFU,CENTER,EE)C . . THIS SUBROUTINE DETERMINES THE OPTIMA SET OF PARAMETERS FOR THEC INFUENCE COEFFICIENT ERROR FUNCTIONS USING THE COMPEX METHODC OF BOX . I T WI AWAYS CONVERGE FOR THE QUADRATIC OBJECTIVEC FUNCTION .

DIMENSION PARMS(ND,NDP1),PAR(ND),PARU(ND),PARO(ND),PAR1(ND),1C(NE,ND,MM),ER(MM,NE),QA(NE,NE),EROBFU(NDP1),W(NE),CENTER(NDP1),2FAC(NE)COMMON /IOSRC/NREAD,NWRITEDATA EPS/1 .OE-03/,ISEED/68457/

C . . MUTIPY THE INVERSE OF THE COVARIANCE MATRIX (QA) AND THE WEIGHTINGC MATRIX, W TO OBTAIN AN OVERA WEIGHTING MATRIX . IF INVERSEC COVARIANCE WEIGHT IS NOT DESIRED, QA IS THE ASSIGNED WEIGHINGC MATRIXC . . CONSTRUCT AN INITIA COMPEX OF POINTS USING THE OD VAUESC OF THE PARAMETERS AND A CUSTER OF RANDOMY GENERATED PARAMETERSC AROUND THE OD SET . ASSUME THAT THE INITIA SET OF PARAMETERS ISC FEASIBE .

DO 10 I=1,NDPAR1(I)=PARO(I)

10

PARMS(I,1)=PARO(I)EROBFU(1)=ERRFNK(ER,C,QA,PARO,PAR1,FAC,ND,NE,MM,NPOINT)DO 35 INDEX=2,NDP1DO 30 I=1,NDICOUNT=O

20

PAR1(I)=PARO(I)-(1 .+(0 .5-RANDU(ISEED))/10 .)C . . CHECK TO SEE IF THE RANDOMY GENERATED PARAMETER IS OUTSIDE THEC FEASIBE REGION

ICOUNT=I COUNT+1IF(ICOUNT-2000) 25,21,21

21

WRITE(6,1000) ICOUNT,I1000 FORMAT(' ---- ERROR

AN ENDESS OOP HAS OCCURRED IN',1' PATSRC (ICOUNT=',I6,')',//,' CHECK THE CONSTRAINTS AND INITIA'2,' PARAMETER SET FOR PARAMETER NO .',I2)GOTO 230

25

IF(PAR1(I) .T .PAR(I)) GOTO 20

212

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IF(PAR1(I) .GT .PARU(I)) GOTO 2030

CONTINUEC . . EVAUATE THE OBJECTIVE FUNCTION

EROBFU(INDEX)=ERRFNK(ER,C,QA,PARO,PAR1,FAC,ND,NE,MM,NPOINT)DO 31 I=1,ND

31

PARMS(I,INDEX)=PAR1(I)35

CONTINUEC . .

SET THE ITERATION COUNTER TO ZEROITER=OIRTRN=O

C . . OOP POINT : THE PROGRAM OOPS BACK TO THIS POINT AFTER SUCCESSFUYC GENERATING A NEW VERTEX .C . . CHECK FOR TERMINATION40

APHA=1 .3C . . DETERMINE IF THE ITERATIONS ARE EXCESSIVE

IF( I TER .GT .ITERM) GOTO 110C . DETERMINE IF THE COMPEX HAS COAPSED, IF SO TERMINATE

VART=O .DO 46 I=1,NDSUM 1=0 .SUM2=0 .DO 44 J=1,NDP1SUMI=SUM1+PARMS(I,J)**2

44

SUM2=SUM2+PARMS(I, J)VAR=(SUM1-(SUM2**2)/NDP1)/(NDP1-1)

46

VART=VART+VARIF(VART .E .EPS) GOTO 200

C . . DETERMINE THE TWO WORST VAUESIWORST=1DO 50 INDEX=2,NDP1

50

IF(EROBFU(INDEX) .GE .EROBFU(IWORST)) IWORST=INDEXC . . CACUATE THE CENTROID OF THE REMAINING POINTS NEGECTING THEC REJECTED POINT .

DO 70 I=1,NDSUM=O .DO 60 J=1,NDP1IF(J .EQ .IWORST) GOTO 60SUM=SUM+PARMS(I, J)

60

CONTINUE70

CENTER(I)=SUM/(NDP1-1)C . . PROJECT FROM THE REJECTED POINT THROUGH THE CENTROID TOC THE NEW TRIA POINT APHA TIMES THE DISTANCE FROM THEC REJECTED POINT TO THE CENTROID75

DO 80 I=1,ND80

PAR1(I)=APHA*(CENTER(I)-PARMS(I,IWORST))+CENTER(I)C . . CHECK TO MAKE SURE THE NEW VERTEX SATISFIES A THE CONSTRAINTS

DO 90 I=1,NDIF(PAR1(I) .T .PAR(I)) GOTO 100IF(PAR1(I) .GT .PARU(I)) GOTO 100

90

CONTINUEC . . NOW CHECK THE ERROR FUNCTION TO SEE IF THE NEW SET OF PARAMETERSC IMPROVES THE OBJECTIVE VAUE .

ERRNEW=ERRFNK(ER,C,QA,PARO,PAR1,FAC,ND,NE,MM,NPOINT)

213

Page 226: Optimal Design and Operation of Wastewater Treatment Plants by

ITER=ITER+1IF(ERRNEW .GT .EROBFU(IWORST)) GOTO 100

C . . IMPROVEMENT . SAVE THE RESUTSEROBFU(IWORST)=ERRNEWDO 95 I=1,ND

95

PARMS(I,IWORST)=PAR1(I)GOTO 40

C . . NO IMPROVEMENT OR CONSTRAINT VIOATION100 APHA=APHA*0 .5

IF(APHA .E .0 .002) GOTO 130IRTRN=IRTRN+1

C . . CHECK FOR EXCESSIVE ITERATIONSIF( ITER .GT .ITERM) GOTO. 110GOTO 75

C . . TERMINATION DUE TO EXECSSIVE ITERATIONS110 WRITE(NWRITE,1010) ITER1010 FORMAT(' PATTERN SEARCH ENDING WITH EXCESSIVE ITERATIONS',

1/,' ITER=',I6)C . . WRITE OUT THE PARAMETER SET TO SHOW HOW COSE IT CAME TOC CONVERGENCE

WRITE(NWRITE,1020)1020 FORMAT(66X,' PARAMETERS')

WRITE(NWRITE,1030) (I,I=1,ND)1030 FORMAT(1X,'VERTEX NO .',6X,'ERROR',6X,6(6X,I2,7X),/,1X,7(6X,12,7X))

DO 120 J=1,NDP1120

WRITE(NWRITE,1040) J,EROBFU(J),(PARMS(I,J),I=1,ND)1040 FORMAT(6X,I2,6X,7E15 .6,/,14X,7E15 .6)

GOTO 200C . . TERMINATION DUE TO AN EXCESSIVE NUMBER OF RETURNS TO THE CENTROID130 WRITE(NWRITE,1050) APHA,ITER1050 FORMAT(' PATTERN SEARCH ENDING WITH EXCESSIVE RETURNS TO THE',

1' CENTROID',/,' APHA=',E17 .6,5X, 'ITER=',I6)WRITE(NWRITE,1020)WRITE(NWRITE,1030) (I,I=1,ND)DO 121 J=1,NDP1

121

WRITE(NWRITE,1040) J,EROBFU(J),(PARMS(I,J),I=1,ND)C . . NORMA TERMINATIONC . . FIND THE BEST PARAMETER SET AND RETURN IT IN PAR1200

IBEST=1DO 210 I=2,NDP1

210

IF(EROBFU(I) .T .EROBFU(IBEST)) IBEST=IDO 220 I=1,ND

220

PAR1(I)=PARMS(I,IBEST)EE=EROBFU(IBEST)RETURN

230

WRITE(6,1060) ((I,PAR(I),PARU(I),PARO(I)),I=1,ND)1060 FORMAT(//,' PARM NO .',I3,' OWER IMIT=',E12 .6,' UPPER IMIT=',

1E12 .6,' ACTUA VAUE=',E12 .6)STOP 45ENDSUBROUTINE PRINTA(A,IPARM,II,IRANK,ND,NE)DIMENSION A(ND,ND,NE),IPARM(ND)COMMON /IOPRT/NREAD,NWRITE

214

Page 227: Optimal Design and Operation of Wastewater Treatment Plants by

WRITE(NWRITE,1000) (IPARM(J),J=1,IRANK)DO 10 I=1,IRANK

10

WRITE(NWRITE,1010) IPARM(I),(A(I,JA,II),JA=I,IRANK)1000 FORMAT(1HO,10I12)1010 FORMAT(1X,I5,10E12 .5)

RETURNENDSUBROUTINE RNKRED(A,B,,IPARM,ND,NE,II,ISI)

C . . THIS SUBROUTINE TESTS FOR PARAMETER INDEPENDENCE, REDUCESC RANK IF NECESSARY, AND STORES THE RESUT IN TWO DIMENSIONAC ARRAY FOR ATER PROCESSING .C IF THE ERROR FUNCTION IS COMPETEY INDEPENDENT OF THE PARAMETERC THE DIAGONA OF THE HESSIAN MATRIX WI BE ZERO .C THIS SUBROUTINE USES THIS INFORMATION TO DETERMINE INDEPENDENCEC AND REDUCE RANK .

DIMENSION A(ND,ND,NE),B(ND,ND),(ND),IPARM(ND)COMMON/IOCOR/NREAD,NWRITEDATA FAC/1 .D-25/

C . . SET IDETEC TO 0 AND USE IT ATER TO DETERMINE IF RANK REDUCTIONSC HAVE BEEN MADEC . . FIND THE MAXIMUM DIAGONA VAUE TO USE TO COMPARE THE OTHER DIAGONAC VAUES TO FIND THE "REATIVE" ZEROS .

BIG=A(1,1,II)DO 10 I=2,ND

10

IF(B IG .T .A(I,I,II)) BIG=A(I,I,II)EPS=FAC %€B I G

C . . NUMBERS ESS THAN EPS ARE "REATIVE" ZEROC . . DETERMINE THE REATIVE ZERO DIAGONAS .

DO 20 I=1,NDC . . ASO USE THIS DO OOP TO ZERO THE IPARM ARRAY

IPARM(I)=0(I)=0

20

IF(A(I,I,II) .T .EPS) (I)=IC . . REDUCE THE RANK OF THE MATRIX BY EIMINATING THE ROWS AND COUMNSC CORRESPONDING TO VAUES .C . . SET THE B ARRAY TO ZERO . IT WAS USED PREVIOUSY IN THE QUADRATICC PROGRAM SUBROUTINE

DO 25 I=1,NDDO 25 J=1,ND

215

25 B(I,J)=0 .0C . . REDUCE THE RANK

ISI=ODO 60 I=1,NDIF(I-(I)) 30,60,30

30 ISI=ISI+1IPARM(ISI)=IISJ=ODO 50 J=1,NDIF(J-(J)) 40,50,40

40 ISJ=ISJ+1

50B(ISI,ISJ)=A(I,J,II)CONTINUE

60 CONTINUE

Page 228: Optimal Design and Operation of Wastewater Treatment Plants by

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Page 229: Optimal Design and Operation of Wastewater Treatment Plants by

DO 350 J=1,ND350 CC(J,I)=0 .0

EE=0 .0DO 450 I=1,M

C*

COMPUTE MATRIX CQC(ND,ND), CQD(ND), AND DQDCA MUTIQ(C(1,1,I),QA,C(1,1,I),CQC,ND,NE,NE,ND)CA MUTIQ(C(1,1,I),QA,D(1,I),CQD,ND,NE,NE,1)CA MUTIQ(D(1,I),QA,D(1,I),DQD,1,NE,NE,1)EE=EE+DQDDO 400 J=1,NDDD(J)=DD(J)+CQD(J)DO 400 K=1,ND

400 CC(K,J)=CC(K,J)+CQC(K,J)450 CONTINUE

GO TO (650,650,500),INC*%` TRANSFER OF OWER IMIT CONDITIONS

500 CA MUTIQ(P,CC,P,TEM1,I,ND,ND,1)CA MUTIP(P,DD,TEM2,1,ND,1,1,ND,1)EE=EE+TEM1(1)-2 .0**TEM2(1)CA MUTIP(CC,P,CQD,ND,ND,I,ND,ND,ND)DO 550 J=1,ND

550 DD(J)=2 .0*(CQD(J)-DD(J))DO 600 I=1,ND

600 BB(I)=PU(I)-P(I)DO 640 J=1,NDK=J+NDDO 620 I=1,NDAA(I,J)=0 .0

620 AA(I,K)=0 .0AA(J,J)=1 .0

640 AA(J,K)=1 .0650 RETURN

ENDSUBROUTINE WOFE(X,XX,A,B,C,P,OBJ,T,COST,DIFF,TT,PRFIT,RATIO,IB,

1 III,OPP,N,M,MN,NZ,NC,ITMAX,MTR,IFAUT)

C` *C* QUADRATIC PROGRAM BY THE WOFE METHOD . *C* MINIMIZES OBJECTIVE FUNCTION (Z) *C* Z = P(J) * X(J) + X(I) * C(I,J) * X(J) + OBJ *C* THE CONSTRAINTS ARE *C*

A(I,J) * X(J) E . B(I)C*

A X(J) GT . 0 .0C*

XX(J)=X(J)+X(J)

*C*

*

DIMENSION A(M,MN),B(M),C(N,N),P(N),T(MN,NC),COST(NC),DIFF(NC),1 TT(NC),PRFIT(NC),RATIO(MN),IB(MN),III(NZ),OPP(MN),X(N),XX(N)COMMON /IOSRC/ NREAD,NWRITEIFAUT=OIF (MTR) 350, 350, 351

351 WRITE (NWRITE,123)123 FORMAT ('ON,M,ITERATION IMIT,TRACE IN ORDER')

217

Page 230: Optimal Design and Operation of Wastewater Treatment Plants by

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Page 231: Optimal Design and Operation of Wastewater Treatment Plants by

WRITE(NWRITE,300) N, M, ITMAX, MTRWRITE ( NWRITE,124)

124 FORMAT ('1 A MATRIX')DO 225 I = 1, MWRITE (NWRITE, 100) (A(I,J), J = 1, N)

225 CONTINUEWRITE (NWRITE, 125)

125 FORMAT ('1 B VECTOR (CONSTRAINTS)')WRITE(NWRITE,100)(B(J),J=1,M)WRITE (NWRITE, 126)

126 FORMAT ('1 C MATRIX (OBJ . FCT .)')DO 230I=1, NWRITE (NWRITE, 100) (C(I,J), J = 1, N)

230 CONTINUEWRITE (NWRITE, 127)

127 FORMAT ('1 P VECTOR (COST COEFF .)')WRITE(NWRITE,100)(P(I),I=1,N)

350 MP1=M+1MM1=M-1NP1=N+1NP2=N+2MNM1=MN-1MNP1=MN+1MNP2=MN+2NV=MN+NNVP1=NV+1NVP2=NV+2NY=NV+MNYP1=NY+1NYP2=NY+2NZP2=NZ+2DO 180 I=1,MNDO 180 J=1,NC

180 T(I,J)=0 .0DO 182 I=1,M

182 T(I,1)=B(I)DO 183 I=MP1,MNJ=I-M

183 T(I,1)=-P(J)DO 184 I=1,MDO 184 J=1,NJP1=J+1

184 T(I,JP1)=A(I,J)DO 185 I=1,NDO 185 J=1,NIPM=I+MJP1 =J+ 1

185 T(IPM,JP1)=2 .*C(I,J)DO 186 I=MP1,MNIMM=I-MDO 186 J=NP2,MNP1JMN=J-N-1

186 T(I,J) = A(JMN,IMM)

219

Page 232: Optimal Design and Operation of Wastewater Treatment Plants by

DO 187 I=1,MNIJ = I + NVP1DO 187 J = NYP2, NCIF(J-IJ)187,179,187

179-T(I,J)=1 .187 CONTINUE

DO 188 I = MP1, MNIJ = I - M+MNP1DO 188 J = MNP2, NCIF(J-IJ)188,178,188

178 T(I,J)=-1 .188 CONTINUE

DO 208 I=1,MNOPP(I) = T(I,1)

208 CONTINUEDO 340 J=1,NZ

340 COST(J)=0 .0DO 189 I=1,MJ=NP1+I

189 COST(J)=T(I,1)DO 190 J=NYP2,NC

190 COST(J)=1 .E+70NN=NZ-MNDO 25 KK=1,NZ

25 III(KK)=KKDO 1 I=1, MN

1 IB(I)=NN+IK=0

C

ITERATION START19 K=K+1

DO 2 J=1,NC2 PRFIT(J)=O .DO 3 J=1,NCSUM=O .DO 4I=1, MNJJ=IB(I)+1

4 SUM=SUM+COST(JJ)*T(I,J)PRFIT(J)=SUM

3 DIFF(J)=COST(J)-PRFIT(J)IF(MTR)555,666,555

555 WRITE(NWRITE,111)KC

PRINT TABE IF DESIRED .WRITE(NWRITE,102)(COST(J),J=2,NC)WRITE(NWRITE,103)(III(KK),KK=1,NZ)DO 26 I=1,MNJJ=IB(I)+1

26 WRITE(NWRITE,104)COST(JJ),(T(I,J),J=1,NC)WRITE(NWRITE,105)(PRFIT(J),J=1,NC)WRITE(NWRITE,106)(DIFF(J),J=2,NC)

220

C FIND THE PIVOT EEMENT --- T(IPR,IPC)666 IPC=O

CTEST--O .FIND THE VARIABE WITH THE ARGEST PROFIT

Page 233: Optimal Design and Operation of Wastewater Treatment Plants by

DO 5 I=2,NC235 IF ( DIFF(I) - TEST) 6, 5, 5

6 TEST=DIFF(I)IPC=I

5 CONTINUEIF(IPC)99,99,7

7 KCK=ODO 8 I=1,MNIF(T(I,IPC))32,32,20

20 RATIO(I) = T(I,1) / T(I,IPC)GO TO 8

32 KCK=KCK+1IF(KCK-MN)21,31,21

21 RATIO(I)=1 .E208 CONTINUE

C

REMOVE IMITING VARIABEDO 9 I=1,MNIF(RATIO(I))9,10,10

10 IF(RATIO(I) .GT .10000 .)RATIO(I)=10000 .TEST=RATIO(I)IPR=IGO TO 11

9 CONTINUE11DO121 =1, MN

IF(TEST-RATIO(I))12,12,1313 TEST--RATIO(I)

IPR=I12 CONTINUE

C

START PIVOTING AND INTRODUCING NEW VARIABE INTO SOUTIONPIVOT=T(IPR,IPC)

C . . THE NEXT STATEMENT WAS ADDED BY MKS ON 8/21/83 TO TEST FORC PIVOT=O AND EXIT THROUGH THE NORMA EXIT IF PIVOT=O .

IF(PIVOT .EQ .O .) GOTO 9998DO 15 J=1,NC

15 T(IPR,J)=T(IPR,J)/PIVOTDO 171 I=1,MNIF(I-IPR)17,171,17

17 DO 18 J=1,NC18 TT(J)=T(IPR,J)*T(I,IPC)/T(IPR,IPC)

DO 172 J=1,NC172 T(I,J)=T(I,J)-TT(J)171 CONTINUE

COST(IPR)=COST(IPC)IB(IPR)=IPC-1

C

TRACE OUTPUT IF DESIRED .IF(MTR-1)205,205,86

86 WRITE(NWRITE,114)DO 87 I=1,MN

87 WRITE (NWRITE,300) I, IB(I)WRITE(NWRITE,119)WRITE(NWRITE,121)IPR,IPC,KCKWRITE(NWRITE,120)WRITE(NWRITE,100)TEST,PIVOT,DIFF(IPC)

221

Page 234: Optimal Design and Operation of Wastewater Treatment Plants by

WRITE(NWRITE,117)DO 88 I=1,MN

88 WRITE (NWRITE,302) I, RATIO(I)C RECOMPUTE COSTS

205 DO 176 J=1,NYP1176 COST(J)=0 .

DO 197 I=1,MNIF(IB(I)-MN)192,192,195

192 JJ=IB(I)+MNP1GO TO 198

195 IF(IB(I)-NY)196,196,197196 JJ=IB(I)-MNM1

GO TO 198198 COST(JJ)=T(I,1)197 CONTINUE

IF(K - ITMAX) 19, 830, 830C . . THIS WRITE STATEMENT INCUDED TO ACCOMODATE THE MODIFICATIONSC MADE FOR UNBOUNDED SOUTIONS AND PIVOT=0 .9998 WRITE(6,1001)1001 FORMAT(' PIVOT =0 .')

IFAUT=1GOTO 999

99 DO 200 I=1,NIF(XX(I) .E .0 .0) XX(I)=X(I)

200 CONTINUESUM=O .DO 201 I=1,MNIN=IB(I)IF(IN .GT .N)GO TO 201XX(IN)=X(IN)+T(I,1)SUM=SUM+P(IN)*T(I,1)

201 CONTINUEFRST=SUMSUM=O .DO 202 I=1,MNDO 202 J=1,MNIN=IB(I)IF(IN .GT .N)GO TO 202JN=IB(J)IF(JN .GT .N)GO TO 202SUM=SUM+C(IN,JN)*T(I,1)*T(J,1)

202 CONTINUESCND=SUMOBJ=FRST+SCND+OBJWRITE(NWRITE,107) OBJWRITE(NWRITE,118)N,NP1,MNWRITE(NWRITE,122)MNP1,NY,NYP1,NZWRITE(NWRITE,108)WRITE (NWRITE,128)DO 28 I=1,MNIF ( T( 1,1)) 27, 28, 27

27 WRITE(NWRITE,110)IB(I),T(I,1)28 CONTINUE

222

Page 235: Optimal Design and Operation of Wastewater Treatment Plants by

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Page 236: Optimal Design and Operation of Wastewater Treatment Plants by

RETURNENDFUNCTION IDFIX(A)IDFIX=ARETURNEND

224