Lecture 0. Prerequisite Information for Wastewater

Treatment Design

By

Husam Al-Najar

The Islamic University of Gaza- Civil Engineering Department

Advance wastewater treatment and design (WTEC 9320)

Source of Wastewater

Sources of

Wastewater Processing at

the Source Wastewater

Collection

Transmission

and Pumping Treatment Reuse/Disposal

Types of collection systems

Separate system

Sanitary system

Combined system

Both sanitary & storm water Storm water

Generally, most of the countries

recently preferring separate systems.

Sources of Wastewater

(Major Components)

1. Domestic: food, soap and detergents, bathroom (fecal and urine), and paper.

1.1. Gray water: Washing water from the kitchen, bathroom, laundry (without faeces and urine)

1.2. Black water: Water from flush toilet (faeces and urine with flush water)

1.3. Yellow water: Urine from separated toilets and urinals

1.4. Brown water: Black water without urine or yellow water

2. Commercial: bathroom and food from restaurants and other “stores.”

3. Industrial: highly variable, dependent on industry, controlled by pre-treatment

regulations.

4. Runoff from streets: sand and petroleum and tire residues (infiltration, not a direct

discharge).

Sewer: Sewers are under ground pipes or conduits which carry sewage to points of

disposal.

Sewage: The Liquid waste from a community is called sewage. Sewage is classified into

domestic and non-domestic sewage. The non domestic sewage is classified into industrial,

commercial, institutional and any other sewage that is not domestic.

Sewerage: The entire system used for collection, treatment and disposal of Liquid waste.

This includes pipes, manholes, and all structures used for the above mentioned purposes.

Infiltration: It is the water which inters the sewers from ground water through Leaks from

loose joints or cracks.

Inflow: It is the water which inters the sewers from the manholes during rainfall events.

DIFINITIONS

An Epidemiologist is a public health scientist, who is responsible for carrying out all useful and

effective activities needed for successful epidemiology practice

Endemic: المتوطنة األمراض a disease or pathogen present or usually prevalent in a given population or

geographic region at all times

Hyperendemic: equally endemic in all age groups of a population

Holoendemic: endemic in most of the children in a population, with the adults in the same population

being less often affected

Epidemic: وباء a disease occurring suddenly in numbers far exceeding those attributable to endemic

disease; occurring suddenly in numbers clearly in access of normal expectancy

Pandemic: a widespread epidemic distributed or occurring widely throughout a region, country,

continent, or globally

Epizootic: of, or related to a rapidly spreading and widely diffused disease affecting large numbers of

animals in a given region.

Incidence: rate of occurrence of an event; number of new cases of disease occurring over a specified

period of time; may be expressed per a known population size

Prevalence: number of cases of disease occurring within a population at any one given point in time

Outbreak: Sudden occurrence of an epidemic in relatively limited geographic area. While an outbreak is usually limited to a small focal area, an epidemic covers larger geographical areas & has more than one focal point.

Outbreak Epidemiology: Study of a disease cluster or epidemic in order to control or prevent further spread of the disease in the population.

Terms Associated with Disease Causation, etc.

Host: Any organism that can be infected by a pathogen under natural conditions

Agent: A factor such as a microorganism, chemical substance, or a form of radiation, the presence or absence of which (as in deficiency diseases) results in disease or more advanced disease.

Fomites واالشياء المالبس : Any inanimate ,.or nonpathogenic substance or material (e.g جمادsheets, surfaces of furniture, papers and so forth), exclusive of food, which may act as a vector for a pathogen

Vector: a carrier, especially the animal (usually an arthropod مفصلية حيوانات as an insect, spider) that transfers an infective agent from one host to another

Carrier – active: One who harbors a pathogenic organism for a clinically significant time and is able to pass the infection to others

Incubatory: The development of an infection from the time the pathogen enters the body until signs or symptoms االعراض first appear.

General Types of Water Pollutants

Causative

agent العامل

Reservoir المسبب للمرض

المصدر

Portal of

exit بوابة

الخروج

Mode of

transmission طريقة

انتقال

Portal of

entry بوابة

الدخول

Susceptible host

المضيف

Components of the infectious disease process- Chain of infection

سلسلة العدوى -مكونات عملية االصابة باألمراض المعدية

Modes of Transmission

Classification of transmission mechanism: It is known today that water-related diseases are

transmitted in four distinct mechanisms.

These include water-born, water-washed, water-based and water-related insect vector.

1. Water-born mechanism: this refers to the situation when the pathogen is in water which is

drunk by a person or an animal which may then become infected. Infections in this group

include cholera, typhoid, infectious hepatitis, diarrheas and dysenteries.

2. Water–washed mechanism: this includes diseases that can be significantly reduced if the

water volume used is increased. Thus quantity rather than quality is important in this

category. The relevance of water to these diseases is that it is an aid to hygiene and

cleanliness. This category includes types: Intestinal tract infection, such as diarrhea diseases

like cholera, bacillary dysentery. Thus are all faecal-oral in their transmission route and

therefore can be water-washed or water born. Skin or eyes infections: bacterial skin sepsis,

scabies, fungal infections, trachoma are examples.

3. Water-based mechanism: a water-based disease it one in which the pathogen spends a part of

its life cycle in a water snail or other aquatic animal.

All these diseases are due to infection by parasitic worms which depends on aquatic

intermediate host to complete their life cycle. Important examples are schistosomiasis, and

Guinea worm (Dranculus medinensis ).

4. Insect vector mechanism. In this case, insects breed in water or bite near water. Examples

include Malaria, Yellow fever, and onchocerciasis.

5. Chemical – related diseases

Due to the presence of harmful or fatal chemicals in water. This can be due to accidental

discharge of sufficient toxic matter into a water source.

Or due to long –term hazard due to exposure to minute concert concentrations, perhaps over

many years, example, lead piping and tanks in domestic plumbing.

Each day some 30000 people die from water–related diseases. In developing

countries 80 percent of all illness water– related (WHO)

Caused by polluted beach water

oGastroenteritis التهاب المعدة واألمعاء

oDiarrheal – 3 million death

oEncephalitis التهاب الدماغ

oStomach cramps and aches وآالم تقلصات في المعدة

oVomiting قيء

oHepatitis االلتهاب الكبدي

Infectious diseases caused by pathogens

oTyphoid

oGiardiasis

oAmoebiasis

oAscariasis

oHookworm

Liver damage and even cancer

Kidney damage

Neurological problems

Reproductive and endocrine damage التناسلي والغدد الصماء

Thyroid system disorders اضطرابات الغدة الدرقية

Why Treating Wastewater?

Domestic and industrial processes use and pollute water => wastewater

Minimize effects of discharge on environment

Remove pollutants for recycling and/or reuse of water

Objectives of Wastewater Treatment

• Ensure good water quality in natural environment

• Remove pollutants most efficiently and economically

• Avoid or minimize other environmental impacts like:

– solid disposal

– gas emission

– odour creation

– noise generation

How to Treat Wastewater????

Classification of Organisms:

The classification of macro- and microorganisms was based primarily on

physiological differences (from two to six major kingdoms proposed for categorizing

life)

In the 1970s techniques become available to examine the Nucleic acids, specially

ribosomal RNA (rRNA), which involved in translation the synthesis of proteins in

the living things.

Based on the analysis of 16s rRNA, Carl Woese identified an entirely new group of

organisms (The Archaea).

This lead to the modern classification of living things into a three-domain system.

(Archaea, Eucarya, and Bacteria).

Archaea are neither Bacteria nor Eukaryotes. Looked at another way, they are

Prokaryotes that are not Bacteria.

The three domain system

The three- domain tree of life

Breakdown (Catabolism)

Proteins to Amino Acids, Starch to Glucose

Synthesis (Anabolism)

Amino Acids to Proteins, Glucose to Starch

Metabolism = Anabolism + Catabolism

Microbial Planktonic Community

Plankton refers to the microbial communities suspended in the water column

Photoautotrophic organisms

within this community including

both eukaryotes (algae) and

prokaryotes (cyanobacteria) are

collectively referred to as

phytoplankton العوالق

Suspended heterotrophic

bacterial populations are

referred to as

bacterioplankton

protozoan

populations make

up the

zooplankton.

Ch

em

otro

pic

: Mic

roorg

anis

ms th

at

extra

ct e

nerg

y fro

m c

hem

ical re

actio

ns

(oxid

atio

n / re

ductio

n re

actio

ns).

Classification of microorganisms

energy and carbon source

Hete

rotro

ph

ic:

Mic

roorg

anis

ms th

at u

se

org

anic

matte

r as a

sourc

e o

f

carb

on

Au

totro

ph

ic: M

icro

org

anis

ms th

at u

se

CO

2 as a

carb

on s

ourc

e

Ph

oto

trop

hic

: Mic

roorg

anis

ms th

at re

ly o

nly

on th

e lig

ht fo

r energ

y

Types of -trophs

Type

Energy

C source

Example

Photoauto-

Sun

CO2

Purple بنف ي &

Green sulfur

bacteria

Photohetero-

Sun

Organic

Compounds

Purple & Green

Non-sulfur

bacteria

Chemoauto-

Chemical bonds

CO2

H, S, Fe, N

bacteria

Chemohetero-

Chemical bonds

Organic

Compounds

Most bacteria,

fungi, protozoa,

animals

Metabolism Electron donor (TEA) Carbon

source

Metabolism type

Respiration

Aerobic

Anaerobic

Fermentation

(Anaerobic only)

Organic compounds

(O2)

(NO3-, Fe3+, SO4

2-)

Organic compounds

(organic acid)

Organic

compounds

Chemohetrotroph

Psedomonas, Bacillus

Micrococcus, Geobacter, Desulfovibrio

Escherichia, Clostridium

Chemolithotrophy

Aerobic

Anaerobic

H2, S2-, NH4

-, Fe2+

(O2)

(NO3-)

CO2

Chemohetrotroph or

Chemolithotroph

Hydrogen bacteria,

Beggiaton

Planctomycetes

Phytosynthesis

Oxygenic

Anoxygenic

Light + H2O (NADP)

Light + H2S

(bacteriochlorophyll)

CO2

Photoautotroph

Cyanobacteria

Bacteria including purple sulfur bacteria

Phytohetrotrophy Light + H2S

(bacteriochlorophyll)

Organic

compounds

Photoheterotroph

Many purple nonsulfur bacteria purple sulfur bacteria

Metabolic Classification of Bacteria

The carbon cycle is dependent on autotrophic organisms that fix carbon

dioxide into organic carbon and hetrotrophic organisms that respire organic

carbon to carbon dioxide.

By their relation to oxygen

Classification of microorganisms

Key for respiration is the Terminal Electron Acceptor (TEA) that is used to deliver

electron to the electron transport chain.

• Under aerobic condition, the TEA is oxygen (38 ATP per glucose metabolism)

• Under anaerobic condition, an alternative TEA such as NO3-, Fe3+, SO4

2- or CO2 is

used. (2 ATP is less than aerobic except for NO3)

• Under facultative aerobes, either O2 or NO3 (Pseudomonas is example)

• Fermentation: is anaerobic process that uses only substrate level phosphorylation

with a net generation of 2 ATP per glucose.

No use for electron transport chain or for an external electron acceptor. Instead,

electrons are shunted among organic compounds usually ending in the production of

acids or alcohols and resulting in very small amount of energy.

• Bacterial growth is a complex process involving numerous anabolic and

catabolic reactions.

• Ultimately, these biosynathetic reactions result in cell division.

• In homogeneous rich culture medium, under ideal conditions, a cell can

divide in as little as 10 minutes.

• In contrast, it is found that the cell division may occur as slowly as once in

100 years in some subsurface terrestrial environments.

• Most of the information concerning the growth of microorganisms is the

result of controlled laboratory studies using pure culture.

• There are two approaches to the study of the growth under such

controlled conditions: Batch culture and Continuous culture.

Bacterial Growth

Binary Division

Growth in Batch culture (pure culture in a flask)

The growth of a single organism or group of organisms, called a

consortium, is evaluated using a defined medium to which a fixed amount

of substrate is added.

several distinct phases:

– Lag phase

– Exponential growth

– Stationary phase

- Death phase

It is difficult to extend our knowledge of growth under controlled laboratory

conditions to an understanding of growth in natural soil or water

environments, where enhanced level of complexity are encountered such

as:

1. Microbial interaction with organic and metal contaminants

2. Survival and growth or pathogens in the environment.

The number of cells present can be determined by viable plate counting (i.e., culturing),

direct microscopic counting, and/or turbidity (i.e., optical density)

Growth Phases

- Is thought to be due to the physiological adaptation of the cell to the cultural

condition.

- When microbes inoculated into fresh medium they do not start to grow

immediately (lag phase)

- Length of lag phase variable – depends on history of the culture and growth

conditions

– exponentially growing culture inoculated into same media, same growth

conditions – no lag phase

The Lag phase

– old culture, same media & conditions – lag phase because cells need to

replenish essential constituents to start growth & cell division cycle

– Cells damaged (heat, radiation, toxic chemicals) - lag phase as cells

repair damage

– Cells transferred from rich medium to poor culture medium, lag phase as

cells have to synthesize more enzymes etc. to enable synthesis of

macromolecules not present in poor culture medium.

- Each cell divides to form 2 cells; 2 cells divide to 2 cells; 2 cells divide to form 4 cells ……

- Rate of exponential growth influenced by environmental conditions (temperature,

composition of culture composition of culture medium) & genetic

characteristics of organism

The Exponential Phase

xdt

dx Where, x is the number or mass of cells (mass/volume), t is time and is

the specific growth rate constant (1/ time)

dtx

dxRearrange

x

x

t

o

dtx

dx

0

For x to be doubled: 2ox

x

te

2Therefore, Where t is the generation time

Bacteria Undergo Exponential Growth

• In a batch culture exponential growth cannot occur indefinitely

– Essential nutrients in medium is used up and/or some waste product of the organism builds

up to an inhibitory advice

– Exponential growth ceases = stationary phase

• In stationary phase – no net increase or decrease in cell number

• Many cell functions continue – energy metabolism, biosynthesis

• In some populations some slow growth may continue – some cells die and some grow – 2

processes balance out so no net change (cryptic growth ( نمو خفي

The Stationary phase

0dt

dx

• If incubation continues after stationary phase, cells may remain alive and

continue to metabolize or they may die = death phase

• In some cases cell death is accompanied by lysis

• Rate of cell death generally slower than that of exponential growth

The Death phase

xKdt

dxd Where Kd is the specific death rate

Effect of substrate concentration on growth

SK

S

s

m

m = maximum specific growth rate, T-1

S = concentration of the limiting substrate, mg/L

Ks = half saturation constant, mg/L

Monod equation, which developed by Jacques Monod in the 1940s:

The above equation is a hyperbolic function as shown on the figure below:

2

m

m

S

Ks Limiting Substrate (mg/l)

There are two constants in this equation, maximum specific growth

rate and Ks, the half saturation constant.

Both reflect intrinsic physiological properties of particular type of

microorganisms.

They also depend on substrate being utilized and temperature of growth.

Monod equation can be expressed in terms of cell number or cell mass (x)

as the following:

m

SK

Sx

dt

dx

s

m

SK

S

s

m

xdt

dx where

Thus,

The Monod equation has two limiting cases:

1. High substrate concentration: S >> Ks

• Under these condition, growth will occur at the maximum growth rate

2. Low substrate concentration: S << Ks

• This type of growth is typically found in batch flask systems at the end of the

growth curve as the substrate is nearly all consumed.

• It is also the typical growth that happened in the natural environment where

substrate and nutrients are limiting.

xdt

dxm

s

m

K

Sx

dt

dx

S, mg/L

µ,

1/h

r

µmax

S << KS mixed order S >> KS

Monod Growth Kinetics

• First-order region: S << KS, the equation can be approximated as = maxS / Ks

• Center region, Monod “mixed order” kinetics must be used

• Zero-order region: S >> KS, the equation can be approximated by = max

The Monod equation can also expressed as a function of substrate utilization given that

the growth is related to substrate utilization by constant called cell yield:

dt

dx

Ydt

ds 1

SK

SX

Ydt

ds

s

m1

where, Y= biomass yield = (g) biomass produced / (g) Substrate consumed

Cells Growth in Continuous Culture

Continuous culture: fresh nutrient medium is continually supplied to a well-stirred culture

and products and cells are simultaneously withdrawn.

At steady state, concentrations of cells, products and substrates are constant.

Growth in the environment

Oligotroph (k-Strategists) versus Copiotrophs (r-Strategists)

“The trouble with ecology is that you never know where to start because everything affects

everything else." Robert A. Heinlein, Farmer in the sky, 1950

These terms, r and K, are derived from standard ecological algebra, as

illustrated in the simple Verhulst equation of population dynamics:

where r is the growth rate of the population (N), and K is the carrying

capacity of its local environmental setting

)1(k

nrn

dt

dn

Oligotroph (k-Strategists):

is an organism that can live in a very low carbon concentration, less than one part

per million.

Most oligotrophs are bacteria, though archaean oligotrophs also exist.

Oligotrophs are characterized by slow growth, low rates of metabolism,

and generally low population density.

Long generation time.

They often use energy obtained from metabolism simply for cell maintenance.

oligotrophs may be found a wide range of environments including in deep

oceanic sediments, caves, glacial and polar ice, deep subsurface soil,

aquifers, and ocean water. An example of an oligotrophic bacteria,

Pelagibacter ubique.

Copiotrophs (r-Strategists):

organisms tend to be found in environments which are rich in nutrients,

particularly carbon, and are the opposite to oligotrophs which survive in

much lower carbon concentrations.

May exhibit high rates of metabolism and perhaps exponential growth for

short periods.

May be found in a dormant state (حالة السبات).

Dormant cells are often rounded and small in comparison with lab.

specimens

Dormant cells may become Viable But Non-Culturable (VBNC)

VBNC are thus difficult to culture because cell stress and damage.

In addition many environmental microbes are Viable But Difficult to Culture

(VBDC)

K strategists

Some examples

r strategists

Growth in the environment…. Continue

1. The lag phase:

The lag phase in the natural environment can be much longer than in the batch culture.

This is due to a combination of limited nutrient and suboptimal environmental conditions.

The second explanation for long lag period in the environmental samples is that the capacity

for degradation of an added carbon source may not initially be present within the existing

population. This situation may required a mutation or a gene transfer to introduce appropriate

degradative genes into a suitable population.

One of the first documented cases of gene transfer in soil was the transfer of the plasmid pJP4

from an introduced organism to the indigenous soil population. The plasmid transfer resulted in

rapid and complete degradation of the herbicide 2.4-D.

Once an environment has been exposed to a particular pesticide and developed a community

for its degradation, the disappearance of succeeding pesticide application will occur with

shorter lag periods. This phenomena called adaptation.

2. The Exponential phase:

In the environment the second phase of growth, exponential growth, occurs for only very

brief periods following addition of substrate.

Such substrate might be crop residues, vegetative litter, root residues or contaminants added

or spilled into the environment.

It is the copiotrophic cells, many of which are initially dormant.

Upon substrate addition, these dormant cells become physiologically active and briefly enter

the exponential phase until the substrate is utilized.

3. The Stationary and death phase:

Stationary phase in the laboratory (batch culture) is a period where there is

active cell growth that is matches by cell death.

In the environment the stationary phase is most likely of short duration if it

exist at all.

Recall that most cells never achieve an exponential phase because of

nutrient limitations and environmental stress.

Might they are in dormancy or in maintenance state.

Complicating the issue is the presence of bacteriophage that can

infect and lyse significant portions of the living bacterial community.

Mass balance of Growth:

Growth condition: when the substrate utilized to increase the cell mass.

Non growth condition: when the substrate and some nutrients is limiting, utilization of

the substrate occurs without production of new cells. The energy from substrate

utilization is used to meet the maintenance of the cell.

Cell yield coefficient (y) = g Cell mass production

g Substrate consumed

The value of cell yield is dependent on substrate being utilized.

Substrate Chemical formula Cell yield coefficient (y)

Pentachlorophenol C6HOCl5 0.05

Glucose C6H12O6 0.4

Octadecane C18H36 1.49

Example 1: A bacterial culture is grown using glucose as a source of carbon and energy.

The cell yield is 0.4. What percentage of glucose (substrate) carbon will be found as cell

mass and as CO2. Assume that you start with 1 mole glucose.

Solution:

Glucose = C6H12O6 molecular weight = 180 g/mol.

Cell mass = C5H7NO2 molecular weight = 113 g/mol.

Substrate mass x cell yield = cell mass production

180 x 0.4 = 72 g

Mol cell mass = 72 g cell mass / 113 g = 0.64 mol cell mass

In terms of carbon

Cell mass: 0.64 mol cell x (5 mol C/ mol cell mass) x (12 g/ mol C) = 38.4 g C

Substrate: 1 mol substrate x (6 mol C/ mol substrate) x (12 g/ mol C) = 72 g C

The percentage of substrate carbon found in the cell mass = 38.4 / 72 = 53%

Carbon release as CO2 = 100% - 53% = 47%

As microbes have evolved, standard catabolic pathways have developed for common

carbohydrate and protein containing substrate.

This translates into a cell yield of approximately 0.4 for sugar such as glucose.

Industrialization began in the late 1800s, many new molecules have been

manufactured for which there are no standard catabolic pathways.

Pentachlorophenol is an example to utilize it, a microbe must alter the chemical

structure to allow use of standard catabolic pathways. So microbes must expend

much energy to break the strong bond carbon-halogen. So little energy is left to

produce cells.

In contrast, Octadecane is a hydrocarbon found in petroleum products formed on

early earth, standard catabolic pathways exist for most petroleum compounds thus

the energy is stored to produce new cells.

Why there are such differences in cell yield for Pentachlorophenol,

Glucose and Octadecane substrates?

The carbon cycle, showing both aerobic and anaerobic contributions

The Nitrogen Cycle

Element breakdown % Dry mass of an E. coli Cell

Major elements

Carbon

Oxygen

Hydrogen

Nitrogen

Sulfur

Phosphorus

50

20

8

14

1

3

Minor elements

Potassium

Calcium

Magnesium

Chlorine

Iron

2

0.05

0.05

0.05

0.2

Trace elements

Manganese

Molybdenum

Cobalt

Copper

Zink

All trace elements combined

comprise 0.3% of dry weight of cell

Chemical composition of an E. coli Cell.

59

Wastewater Treatment Plant

Acinetobacter: (-) Phosphorus removal from wastewater

Azotobacter: (-) Nitrogen fixation

Bdellovibrio: (-) attack pathogenic bacteria

Desulfovibrio: (-) sulfate reduction in wastewater

Enterobacter aerogenes: (-) indicator organism

Escherichia coli: (-) indicator organism

Methanobacterium, Methanosarcina : (-/+) methane production

Nitrobacter, Nitrosomonas : (-) Ammonium oxidation

Pseudomonas: (-) Nitrate removal from wastewater

Rhizobium: (-) Nitrogen fixation

Streptococcus: (+) lactic acid production

Thiobacillus: (-) sulfur oxidizer

List of Bacteria should be known for wastewater treatment engineers