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Implementation of Activated Sludge Models (ASMs) for an Aerobic Sludge Digestion Process Maryam Ghorbani (M.A.Sc.) Cigdem Eskicioglu (Ph.D.) University of British Columbia Okanagan Campus
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Page 1: Implementation of (ASMs) for an Aerobic Sludge Digestion Process_ppt

Implementation of Activated Sludge

Models (ASMs) for an Aerobic Sludge

Digestion Process

Maryam Ghorbani (M.A.Sc.)

Cigdem Eskicioglu (Ph.D.)

University of British Columbia Okanagan Campus

Page 2: Implementation of (ASMs) for an Aerobic Sludge Digestion Process_ppt

2

Introduction

Problem Definition

Research Objectives

Model Assumptions

Experimental Design

AquaSim© Software

Parameter Estimation/Sensitivity Analysis

Results

Conclusion & Future Work

Page 3: Implementation of (ASMs) for an Aerobic Sludge Digestion Process_ppt

Activated Sludge Process

3

Wastewater(Influent)

Air

Treated Water(Effluent)

Recycled WAS

Waste Activated Sludge (WAS)

Aerobic Sludge Digestion Tank

Aeration Tank Clarifier/Settler

Reference: http://www.answers.com/topic/sewage-treatment

To River

Landfill

Page 4: Implementation of (ASMs) for an Aerobic Sludge Digestion Process_ppt

Advanced Activated Sludge Models (ASMs)

4

Aim:

To create a common platform for future carbon and

nutrient removal activated sludge processes.

History:

The first model, Activated Sludge Model No: 1 (ASM 1), was

published in 1987 with carbon/nitrogen removal.

In 1995, Activated Sludge Model No: 2 (ASM 2) was

published with biological phosphorous removal.

In 1998, ASM3 was published with bacterial internal storage

compounds.

Page 5: Implementation of (ASMs) for an Aerobic Sludge Digestion Process_ppt

Possible Applications of ASMs

5Reference: www.jswa.go.jp/english/r_d/major_pdf/06.pdf

Master Planning• Process Comparison/Selection

• Planning Future Construction

Detailed Design• Reactor Capacity Consideration

• Equipment Selection

• Upgrading Consideration

• Planning RetrofitRetrofit/Upgrading

• Plant Evaluation

• Making O & M Plan

Operation & Maintenance Assistance

Page 6: Implementation of (ASMs) for an Aerobic Sludge Digestion Process_ppt

Matrix Representation of ASM1 (Henze et al.,1986)

6

Page 7: Implementation of (ASMs) for an Aerobic Sludge Digestion Process_ppt

Matrix Representation of ASM3 (Henze et al., 2000)

7

Page 8: Implementation of (ASMs) for an Aerobic Sludge Digestion Process_ppt

ASM1 versus ASM3

8

Page 9: Implementation of (ASMs) for an Aerobic Sludge Digestion Process_ppt

Problem Definition

9

ASMs have not been tested against a large variety of

data.

Studies focused on modeling of wastewater

processes, rather than sludge digestion.

Some parameters are correlated, individually non-

identifiable.

The majority of parameters can not be

experimentally measured.

Practitioners need parameter identification for

model calibration purposes.

Page 10: Implementation of (ASMs) for an Aerobic Sludge Digestion Process_ppt

Research Objectives

10

To investigate:

Performance of ASMs for aerobic sludge digestion

under different flow regimes.

Kinetic & stoichiometric parameters for batch

and semi-continuous flow runs.

Most sensitive model parameters.

If kinetic parameters determined from batch could

predict semi-continuous flow digester performances at

different operating conditions, i.e. retention time.

Page 11: Implementation of (ASMs) for an Aerobic Sludge Digestion Process_ppt

Model Assumptions

11

DO > 2 mg/L

Anoxic growth of heterotrophic

biomass is not applicable and

So/(KOH+So) ≈ 1

Autotrophic biomass

concentration is a small

percentage of heterotrophs

concentration

Autotrophs (nitrification) are

negligible

Page 12: Implementation of (ASMs) for an Aerobic Sludge Digestion Process_ppt

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Process Rate, ρj

ML-3T-1

5

XH

4

XS

3

XI

2

SS

1

SI

Component, i

Process, j

1Aerobic Growth of

Heterotrophs

-11- fXIfXI

Decay of

Heterotrophs

-11

Hydrolysis of

Entrapped Organics

COD (Chemical Oxygen Demand) Parameter, ML-3

HY

1

Example for batch reactor:

H

SS

S

Hm XSK

S

HH Xb

H

HSX

HS

h XXXK

XXk

HHH

SS

SHm

HX XbX

SK

S

dt

dXr

H

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Particulate COD = XI + XS+ XHSoluble COD = SS + SI

H

H

SX

H

S

hHHXIS X

XX

K

XX

kXbfdt

dX

1

HHXII Xbf

dt

dX

HHH

SS

SHm

H XbXSK

S

dt

dX

0dt

dS I

H

H

SX

H

S

hH

SS

SHm

H

SX

XX

K

XX

kXSK

S

Ydt

dS

1

Total COD = Soluble COD + Particulate COD

Page 14: Implementation of (ASMs) for an Aerobic Sludge Digestion Process_ppt

Component, i

Process, j

1

SI

2

SS

3

XI

4

XS

5

XH

6

XSTO

7

XV

Process Rate, ρj

ML-3T-1

Hydrolysis fSI 1- fSI -1 -iVSSXS

Aerobic Storage

of COD

-1 YSTOO2 0.6YSTOO2

Aerobic Growth

of Heterotrophs

1

Aerobic

Endogenous

Respiration of

Heterotrophs

fXI -1 fXI iVSSXI –

iVSSBM

Aerobic

Endogenous

Respiration of

Stored Organics

-1 -0.6

Parameter, ML-3 COD (Chemical Oxygen Demand)

Soluble COD = SI + SS

Particulate COD = XI + XS+ XH+ XSTO 14

HY

1

H

HSX

HSh X

XXK

XXk

H

SS

SSTO X

SK

Sk

H

VSSBMY

i6.0

H

HSTOSTO

HSTOHm X

XXK

XX

HH Xb

STOSTOO Xb 2

Page 15: Implementation of (ASMs) for an Aerobic Sludge Digestion Process_ppt

15

Soluble COD = SI + SSParticulate COD = XI + XS+ XH+ XSTO

HHXII Xbf

dt

dX

H

H

SX

H

S

hS X

XX

K

XX

kdt

dX

HHH

H

STOSTO

H

STO

HmH XbX

XX

K

XX

dt

dX

H

H

SX

H

S

hSII X

XX

K

XX

kfdt

dS

H

SS

SSTOH

H

SX

H

S

hSIS X

SK

SkX

XX

K

XX

kfdt

dS

1

HHH

HSTOSTO

HSTOHm

H

H

SS

SSTOSTOO

STO XbXXXK

XX

YX

SK

SkY

dt

dX

12

HHVSSBMVSSXIXIH

HSTOSTO

HSTOHm

H

VSSBMH

SS

SSTOSTOOH

HSX

HShVSSXS

V XbiifXXXK

XX

YiX

SK

SkYX

XXK

XXki

dt

dX

6.06.0 2

Page 16: Implementation of (ASMs) for an Aerobic Sludge Digestion Process_ppt

Digester Name 1- B12 1-B5

TSS initial (mg/L) 12 500 5000

Duration (days) 30 30

Digester Name 2- B12 2-B5-1 2-B5-2

TSS initial (mg/L) 12 500 5000 5000

Duration (days) 70 70 70

Digester Name 1-C5 1-C10 1-C20

Solid Ret. Time

(days)

5 10 20

Flowrate (mL/d) 1000 500 250

TSS initial (mg/L) 5000 5000 5000

Duration (days) 53 53 53

16

Batch digesters

Dissolved oxygen ≥ 2 mg/L

Temperature = 20 ± 2 OC

Sludge was taken from municipal

wastewater treatment plant

(ROPEC) in Ottawa

Volume = 20 L

Semi-continuous digesters

Volume = 5 L

1st

Run

2 nd

Run

Page 17: Implementation of (ASMs) for an Aerobic Sludge Digestion Process_ppt

The sludge was taken from municipal WWTP in Kuwait

Dissolved oxygen ≥ 4 mg/L

Temperature = 20 ± 20C

17

Volume = 10 L

Batch digester (Automated fermentor)

Al-Ghusain et al., 2002

Page 18: Implementation of (ASMs) for an Aerobic Sludge Digestion Process_ppt

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Developed by EAWAG (Switzerland)

Simulation (solving differential

equations)

Parameter estimation

Sensitivity analysis

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Calibrate and validate the model

Determine best identifiable parameter

subsets

Determine reduced set

Computer sensitivities

Computer simulation

Assume parameters from literature

Select the kinetic model, i.e. ASM1

Step 4:

Step 2:

Step 1:

Step 0:

Step 3:

Page 20: Implementation of (ASMs) for an Aerobic Sludge Digestion Process_ppt

20

ERROR EQUATION

where:

is the mean of observed values, yi is the observed value, represents the

value of predicted variable (such as digester COD)

n is number of the data points

n

i

i

n

i

ii

yy

yy

R

1

2

1

2

2

ˆ

1

yiy

Batch Digesters

Page 21: Implementation of (ASMs) for an Aerobic Sludge Digestion Process_ppt

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ERROR EQUATION

where:

is the residual, the difference between the predicted and observed value in

mg/L.

n is number of predication/observation pairs.

ir

Semi-Continuous Reactors

n

i

irn

RMSR1

2 )(1

Page 22: Implementation of (ASMs) for an Aerobic Sludge Digestion Process_ppt

22

where:

y : arbitrary variable calculated by AquaSim© (such as digester COD)

p: model parameter (such as YH, bH)

Measures the relative change in “y”

for a 100% change in “p”.

RELATIVE- RELATIVE SENSITIVITY FUNCTION:

p

y

y

prr

py

,

,

Page 23: Implementation of (ASMs) for an Aerobic Sludge Digestion Process_ppt

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Page 24: Implementation of (ASMs) for an Aerobic Sludge Digestion Process_ppt

Batch Runs

Parameter- Units

Estimation

Range

Starting

Value

Reactor 2-B12 Reactor 2-B52

Before

identification

After

identification

Before

identification

After

identificationRepresentative

bHd-1 0.1-1.6 0.62 0.24 0.28 0.43 0.44 0.39 ± 0.24

fxig COD/g COD 0.04-0.2 0.08 0.06 0.11 0.07 0.07 0.09 ± 0.03

khd-1 0.5-20 3 0.58 0.58 0.77 0.77 0.66 ± 0.13

YHg COD/g COD 0.3-0.8 0.67 0.79 0.80 0.84 0.85 0.80 ± 0.04

Kx- 0.01-0.1 0.03 0.10 0.10 0.10 0.10 0.10 ± 0.00

μHmd-1 3-15 6 14.39 14.39 14.70 14.70 14.46 ± 0.30

Ksmg COD/L 10-200 20 10.00 10.00 10.00 10.00 10.00 ± 0.00

Overall R2 0.98 0.98 0.96 0.95

24

Page 25: Implementation of (ASMs) for an Aerobic Sludge Digestion Process_ppt

Parameter- Units

Estimation

Range

Starting

Value

Reactor 2-B12 Reactor 2-B52

Before

identification

After

identification

Before

identification

After

identificationRepresentative

bHd-1 0.1-2 0.2 0.10 0.10 0.11 0.10 0.10 ± 0.00

fxig COD/g COD 0.15-0.25 0.2 0.25 0.25 0.24 0.24 0.22 ± 0.04

khd-1 0.5-5 3 0.51 0.52 0.71 0.54 1.32 ± 0.80

Kx- 0.03-5 1 4.76 4.84 4.57 4.53 4.86 ± 0.20

YHg COD/g COD 0.3-0.8 0.63 0.79 0.79 0.74 0.75 0.79 ± 0.02

μHmd-1 1-9 2 8.51 8.51 1.03 1.03 5.49 ± 4.04

Ksmg COD/L 1-50 2 1.00 1.00 1.00 1.00 1.00 ± 0.00

KSTOg COD/g COD 0.5-2 1 1.83 1.83 1.90 1.90 1.68 ± 0.56

kSTOd-1 2-10 5 2.00 2.00 2.00 2.00 2.00 ± 0.01

fSIg COD/g COD 0.005-0.05 0.01 0.005 0.005 0.005 0.005 0.005 ± 0.000

bSTOO2d-1 0.1-4 0.2 0.13 0.13 0.10 0.10 0.11 ± 0.01

YSTOO2g COD/g COD 0.6-0.9 0.85 0.89 0.90 0.61 0.60 0.81 ± 0.13

Overall R2 0.98 0.98 0.94 0.94

25

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ASM1

ASM3

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ASM1

ASM3

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24

ASM1

ASM3

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29

24

ASM1

ASM3

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Page 31: Implementation of (ASMs) for an Aerobic Sludge Digestion Process_ppt

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24

ASM1

ASM3

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Page 33: Implementation of (ASMs) for an Aerobic Sludge Digestion Process_ppt

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24

ASM1

ASM3

Page 34: Implementation of (ASMs) for an Aerobic Sludge Digestion Process_ppt

34

ERROR EQUATION

where:

and are the model predictions for validation and calibration data sets.

and represent the experimental (observed) values validation set and

with calibration values, respectively.

n and m are number of the calibration and validation data points.

n

i

cici

m

i

vivi

n

yy

m

yy

J

1

2

1

2

2

)ˆ(

)ˆ(

viy ciy

viy ciy

Between 0 and ∞

ASM1 ASM3J=1.44 J=0.65

Page 35: Implementation of (ASMs) for an Aerobic Sludge Digestion Process_ppt

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Page 36: Implementation of (ASMs) for an Aerobic Sludge Digestion Process_ppt

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Digester COD and VSS are sensitive to YH, fiini, fxi, bH, fxsini, fssini, kh, KX, µHm, and

KS ranging from the most to the least sensitive parameter.

-0.5

0.0

0.5

1.0

1.5

2.0

0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75

Re

lati

ve-R

ela

tive S

en

s. (

CO

D )

Time (days)

b_H f_xi Y_H f_i_ini f_xs_ini

f-i-inif-xi

b-H

f-xs-ini

(Yield Coefficient)

(Decay Coefficient)

(endogenous fraction of

biomass leading to inert part)

(ratio of initial inert PCOD

to initial TCOD)

(ratio of initial particulate

degradable COD to initial TCOD)Y-H

Page 37: Implementation of (ASMs) for an Aerobic Sludge Digestion Process_ppt

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Both ASM1and ASM3 predicted COD and VSS concentrations

successfully.

ASM3 parameters were more consistent throughout the runs.

ASM1 overestimated COD & VSS after15 d during validation.

Batch kinetic coefficients can successfully simulate continuous-

flow aerobic digesters.

Future work:

Validating semi-continuous results with independent data set.

Checking the performance of ASMs on industrial WAS.

Checking the performance of ASMs on a full-scale WWTP.

Page 38: Implementation of (ASMs) for an Aerobic Sludge Digestion Process_ppt

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Special thanks to:

Dr. Cigdem Eskicioglu, UBC Okanagan

Dr. Ronald L. Droste, University of Ottawa

Dr. Mohammad Hamoda, University of Kuwait

UBC Okanagan for Start-up Funds

Page 39: Implementation of (ASMs) for an Aerobic Sludge Digestion Process_ppt

THANK YOU

39


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