System-wide Benchmark Simulation Model for

integrated analysis of urban wastewater

systems

Ramesh Saagi1, Xavier Flores-Alsina2, Krist. V. Gernaey2, Ulf Jeppsson1

1 Division of Industrial Electrical Engineering and Automation (IEA), Lund University, Sweden2 Department of Chemical and Biochemical Engineering, Technical University of Denmark (DTU), Denmark

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Outline

1. Objective

2. The urban wastewater system (UWS)

3. Modelling the UWS– Catchment

– Sewer network

– WWTP

– Receiving water

4. Evaluation criteria– River quality based evaluation

5. Results

6. Conclusions

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Objective

• Spatial extension to plant-wide BSM

“Outside the fence” of WWTP

• River quality based evaluation

• Benchmarking of integrated control strategies

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The urban wastewater system

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Modelling the UWS - Catchment

CODsol CODpart NH4 NO3- PO4

- Flow rateStates

subcatchment Area (ha) PEDWF (m3/d)

Infiltration (m3/d)Storage tank volume (m3)

Domestic Industrial

1 99 15,920 2,390 700 5500

2 21 3,920 590 2,500 150 1000

3 29 2,960 440 200 2000

4 71 9,600 1,440 500 4000

5 71 7,840 1,180 1,600 4000

6 249 39,760 5,960 1,700 15000

Total 540 80,000 12,000 2,500 4850 31500

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Modelling the UWS - Catchment

Generation of wastewater

• Domestic

• Industrial

• Stormwater

• Infiltration to sewers

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Modelling the UWS – Sewer system

• Sewer transport – Linear reservoir model

• First flush model for particulate pollutants

• Storage tank models

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Modelling the UWS – WWTP

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Biology (RWQM1)

• 18 state variables

– Organics, biomass, oxygen, nitrogen, phosphorus

• 17 processes

– Heterotrophs, Autotrophs, Algae

– Hydrolysis

– Phosphate processes

Length of each stretch-1kmTotal river length-30km

Hydraulics

Modelling the UWS – River

8 m

14 m

3 m

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Evaluation criteria

River quality based evaluation

• Total exceedance duration

– NH4

– DO

10

NH

4(g

/m3)

hoursDO

(g/m

3)

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Evaluation criteria

River quality based evaluation

• 1-hour max/min conc.

– 1-hour max. NH4 conc.

– 1-hour min. DO conc.

11

NH

4(g

/m3)

hoursDO

(g/m

3)

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Results - CatchmentDomestic Industry

Infiltration Rain

0 90 180 270 3650

200

400

600

800

1000

Time (days)

Flo

w r

ate

(m

3/d

)

100 102 104 106 108 1100

1

2

3

4

5x 10

4

Time (days)

Flo

w r

ate

(m

3/d

)

100 102 104 106 108 1100

1000

2000

3000

4000

5000

Time (days)

Flo

w r

ate

(m

3/d

)

100 102 104 106 108 1100

500

1000

1500

2000

Time (days)

Flo

w r

ate

(m

3/d

)

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Sewer transport – Linear reservoir model

First flush model for particulate pollutants

Results – Sewer system

1 1.2 1.4 1.6 1.8 20

0.5

1

1.5

2x 10

4

Time (days)

Flo

wra

te (

m3/d

)

Inflow

Outflow k=15 min

Outflow k=30 min

Outflow k=300 min

1 1.2 1.4 1.6 1.8 20

0.5

1

1.5

2x 10

4

Time (days)

Flo

wra

te (

m3/d

)

Inflow

n=1

n=2

n=3

n=4

270 271 272 273 274 2750

1000

2000

3000

Time (days)

CO

Dp

art a

ccu

mu

late

d (

kg

)

270 271 272 273 274 2750

2

4

6x 10

4

Time (days)

CO

Dp

art lo

ad

(kg

/d)

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Online storage Offline storage

172 173 174 175 176 177 1780

1

2

3

4

5x 10

5

Time (days)

Flo

wra

te (

m3/d

)

inflow

throttle

overflow

172 173 174 175 176 177 1780

1

2

3

4

5x 10

5

Time (days)

Flo

wra

te (

m3/d

)

inflow

throttle

overflow

Results – Sewer system

Storage tanks

Online tanks with valves

Offline tanks with pumps

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166 166.2 166.4 166.6 166.8 1676

6.5

7

7.5

8

8.5

9

Time (days)

DO

co

nc. (g

/m3)

stretch1

stretch2

stretch3

168.5 169 169.54

5

6

7

8

9

Time (days)

DO

co

nc. (g

/m3)

stretch1

stretch2

stretch3

166 166.2 166.4 166.6 166.8 1670

0.5

1

1.5

2

2.5

Time (days)

NH

4 c

on

c. (g

/m3)

stretch1

stretch2

stretch3

168.5 169 169.50

0.5

1

1.5

2

2.5

3

3.5

Time (days)

NH

4 c

on

c (

g/m

3)

stretch1

stretch2

stretch3

Ammonia variation is generally straightforward

DO variation is highly dynamic and depends on various factors

Results - River

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Conclusions

• System-wide extension to BSM2

• Wastewater generation in the catchment

• Sewer transport model with storage tanks

• Biochemical model for simulation of river dynamics

• River quality based evaluation of control strategies

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Thank you!

www.sanitas-itn.eu

The research leading to these results has received funding from the People Program (Marie

Curie Actions) of the European Union’s Seventh Framework Programme FP7/2007-2013 under

REA agreement 289193.

This presentation reflects only the author’s views and the European Union is not liable for any

use that may be made of the information contained therein.