performance eval and op considerations_wyl_vf

8/21/2019 Performance Eval and Op Considerations_WYL_vf

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Performance Evaluation &

Operational Optimisation

Wah Yuen Long


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Operation of Water Reclamation Plant

While the water reclamation plant can treat

the used water as designed…is it performing

optimally i.e. with minimal use of resources ?

Energy is the main variable resource used


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Energy

• Where are we ?

• Who’s best ?

•

What’s comparison ? • What can be done ?


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Mass Flow and Balance of

UPWRP


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Treatment capacity : 360 000 m3/d

NEWater production : 130 000 m3/d

Ulu Pandan Water Reclamation Plant

Power produced : 48 MWh/d


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Data/information Collection

Regular sampling program: Jan-June 2009

Daily, weekly and monthly

Additional sampling program

Verification by mass balance calculation

Principle equation: A simplification

∑FIN = ∑ RIN + ∑ FOUT

Table 1.1 Three phases, design capacity and processes of Ulu Pandan WRP

Phase Design capacity, m3/d Process

South stream 200 000 Modified Ludzack-Ettinger (MLE)

North stream 61 000 (MLE) +25 000 (MBR)Conventional activated sludge and a MLEMBR

Liquid TreatmentModule (LTM)

75 000two stage (A-B) activated sludge processwithout primary settling tanks


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Hydraulic and solids mass flow


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Mass flow and balance: carbonaceous matters

The ‘true’ CODremoval efficiency of

the PST : 39.3%.

Sludge cake

Dewatering

Digester

Thickener

22.3%

Dewatering centrate

4.8%

3.5% Thickening centrate

Biogas

17.9%

PST sludge 30.2%

44.9%

WAS sludge 14.7%

FSTActivated Sludge

TanksPST

Influent

100%

52.8% Effluent

7.0%

Return Activated Sludge

Dissimilation

in ASTs 53%sludge cake

22%

methane

18%

efflunet

7%

COD distributions at the plant level


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Mass flow: solids

Sludge cake

Dewatering

Digester

Thickener

30.0%

Dewatering centrate

6.0%


Biogas

24.9%

PST sludge 39.7%

62.5%

WAS sludge 22.8%

FSTActivated

Sludge TanksPST

Influent

100%

37.7%Effluent

6.7%


The ‘true’ SS removal

efficiency of the PST :

51.2%.

Dissimilation

in ASTS 38%

sludge cake

30%

methane

25%

efflunet

7%

Solid COD distributions at the plant

level


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Mass flow and balance: nitrogen

Sludge cake

Dewatering

Digester

Thickener

12.7%

Dewatering centrate

10.9%


Biogas

(?)

PST sludge 11.2%

22.6%

WAS sludge 11.4%

FSTActivated

Sludge TanksPST

Influent

100%

48.0%

Effluent

40.3%


The ‘true’ removal

efficiency of PST:

13.2%.

Denitrified

in AST

47%Effluent

40%

Sludge

cake

13%

Nitrogen distributions at the plant

level


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FSTActivated

Sludge TanksPST

Influent

100% Effluent

56.5%


Sludge cake

Dewatering

Digester

Thickener

43.5%

Dewatering centrate

20.4%

19.0%

Thickening centrate

PST sludge 23.1%

63.9%

WAS sludge 40.8%

Mass flow and balance: phosphorus

The ‘true’ removal

efficiency of the

PST: 30%

Effluent

56%

Sludge

cake

44%

Phosphorus distributions at the plant

level


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Energy efficiency

Biogas production Solids generation Energy efficiency

l/m3 influent

sewage

m3/kg solids in

influent sewage

kg solids (dry)/m3

raw sewage

kg solids (dry)/kg

solids in raw

sewage

kWh generated/

m3 raw sewage

kWh/m3 raw

sewage

65 1.88 0.11 0.34 0.15 0.52/0.46

Table Perform indicators of Ulu Pandan WRP

Specific energy

consumption: 0.52

KWH/m3, excluding extralifting , EQ and MBR etc.

for benchmarking: 0.46

KWH/m3.

Electricity generation:

0.15 KWH/m3.

Energy efficiency: 30%


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Strass wastewater treatment plant, Austria

A model of energy self-sufficient: reached 108% of

energy efficiency at 2005, currently 200% with co-digestion


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Strass WWTP, Austria (cont)

Wett B. (2011) Strategies towards improved

energy balances of activated sludge systems -

Austrian case studies, 8 Jan 2011, Miami .

COD mass flow and balance in

mass flow and balance

A-B stage activated sludge process

Wett B., Buchauer K. and Fimml C. (2007) Energy self-sufficiency as a feasible concept for wastewater treatment systems. IWA Leading-Edge

Conference. 4 - 6 June, 2007, Singapore.


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B-stage: SRT, 10 d. NH4-N on-

line sensor based dynamic

aeration control

A-stage: DO, 0.3 mg/L; HRT, 0.5 h; SRT, 0.5 d.

Strass waste water treatment plant, Austria (cont)

Wett B. (2011) Strategies towards improved energy balances of activated sludge systems -Austrian

case studies, 8 Jan 2011, Miami .

S l A i ( )


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Mesophilic

anaerobic

digesters (at

370C)

Deammonification treating ammonia of dewatering contrate

Strass wastewater treatment plant, Austria (cont)

Wett B. (2011) Strategies towards improved energy balances of activated sludge systems -

Austrian case studies, 8 Jan 2011, Miami .


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Strass wastewater treatment plant, Austria (cont)

B-stage

47%

Off gas treatment

13%

Sludge treatment

12%

Pumping station

9%

A-stage

9%

Mechanic

4%

Building

4%

Anammox

2%

Energy consumption and distributions

Specific energy consumption: 0.31 KWH/m3, Electricity generation: 0.34

KWH/m3. Energy efficiency: 108% in 2005.

With co-digestion, the current energy efficiency: 200% .

Wett B., Buchauer K. and Fimml C. (2007) Energy self-sufficiency as a feasible concept for wastewater treatment

systems. IWA Leading-Edge Conference. 4 - 6 June, 2007, Singapor.


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39.2

44.9

17.9

52.9

22.3

7

60.7 b

74.3

35.9

21.8

37.6

4.7

0

10

20

30

40

50

60

70

80

Removed by PST Feed to digesters CH4-COD Dissimilated in

ASTs

Dewatering sludge Final effluent

P e r c e n t a g e ,

%

UPWRP Strass

Benchmarking with Strass WWTP: COD mass distributions

a Wett B., Buchauer K. and Fimml C. (2007) Energy self-sufficiency as a feasible concept for wastewater treatment systems. IWA Leading-Edge

Conference. 4 - 6 June, 2007, Singapore,b Wasted sludge from the A-stage activated sludge process.


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Benchmarking with Strass WWTP : nitrogen mass distributions

a Wett B., Buchauer K. and Fimml C. (2007) Energy self-sufficiency as a feasible concept for wastewater treatment systems. IWA Leading-Edge

Conference. 4 - 6 June, 2007, Singapore,b Due to denitrification by using anammox in the side line.

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20.6

12

40.3

56.6 (41.9 +14.7 b)

43.4

17.916.3

0

10

20

30

40

50

60

Dissimilation bydenitrification

Feed to digesters Dewatering sludge Final effluent

P e

r c e n t a g e ,

%

UPWRP Strass


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0.46

0.31

0.15

0.34

30 %

108 %

0

20

40

60

80

100

120

0

0.1

0.2

0.3

0.4

0.5

0.6

E n

e r g y e f f i c i e n c y ( % )

E n e r g y c o n s

u m p t i o n a n d r e c o v e r y ( k w

h / m 3 )

UPWRP STRASS WTP

Energy consumption (kwh/m3) Energy recovery (kwh/m3) Energy efficiency (%)

Benchmarking with Strass WWTP: Energy efficiencies

Low energy consumption

On line sensor based

aeration control Short aerobic SRT based on

aeration control

Anammox in side line

High energy recovery

Pre-concentrating COD to

AD (74.3% vs 44.9%)

Optimal operation of AD

(370C vs 300C; CH4-COD:

35.9% vs 17.9%)

High efficiency engine (38%

vs 28%)

Gap of energy saving: 30% (0.46 KWH/M3 verse 0.31 KWH/m3);

Gap of energy recovery: 220% (0.15 KWH/m3 verse 0.34 KWH/M3)

Wett B., Buchauer K. and Fimml C. (2007) Energy self-

sufficiency as a feasible concept for wastewater treatment

systems. IWA Leading-Edge Conference 4 - 6 June, 2007,

Singapore.


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Roadmaps towards energy self sufficient: energy


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Roadmaps towards energy self-sufficient: energy

saving

Optimization of activated sludge process

operation

On line sensor based aeration control

Reduce aeration according to optimal aerobic SRT

Improvement of reject operation

Maintain consistent operation of thickening and

dewatering Anammox in side stream


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Aeration energy: effect of DO and MLSS concentrations


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Effects of DO on nitrifier

activity and aeration

Effect of MLSS concentration on aeration

E &H (2011) Biological waste water treatment

optimization in WWTP with analyzers, 15th March,

PUB.

Aeration energy: effect of DO and MLSS concentrations

Aeration energy (cont): effect of aerobic SRT in Singapore conditions


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Aerobic SRT: 3 ~4 days Anoxic SRT: 3 ~ 5 days

HRT: 6-8 h

0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35

Jurong

Kranji

Seletar

Ulu Pandan

Changi

W a t e r R e c l a m a t i o n P l a n t

Energy of aeration (kWh/m3)

The aerobic reactor volume can be cut by 40-50% !

The aeration energy of 0.14 kWh/m3 sewage :54% of 0.26 kWh/m3 sewage of the average of

the other four WRPs

The specific aerobic volume: 0.13 m3/m3 sewage, 40% of the average of the other four WRPs.

Aeration energy (cont): effect of aerobic SRT in Singapore conditions

Aeration energy: effect of aerobic SRT


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Aeration energy: effect of aerobic SRT

Rosenwinkel et al . (2011) Energy saving with Deammonification - process for nitrogen removal - full scale

experiences, Istanbul 04.05.2011

Roadmaps towards energy self sufficient: increase


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Roadmaps towards energy self-sufficient: increase

energy recovery

Pre-concentrating: maximize retention of COD

prior to AST To optimize design and operation of PSTs

Chemical addition

To use A - stage activated sludge instead PSTs Enhancing anaerobic digester performance

Optimal temperature control

Optimal feed pattern

Optimal mixing

Sludge pre-treatment

Additional substrate


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Energy-balance (demand and yield)


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Energy balance (demand and yield)

Rosenwinkel et al. (2011) Energy saving with Deammonification - process for nitrogen removal - full scale experiences,

Istanbul 04.05.2011.


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fats oils and greases (FOG) and sludge co-digestion


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fats, oils and greases (FOG) and sludge co-digestion

0

100,000

200,000

300,000

400,000

500,000

600,000

700,000

Jan-07 Apr-07 Jul-07 Oct-07 Jan-08 Apr-08 Jul-08 Oct-08 Jan-09 Apr-09

Month

B i o g

a s p r o d u c t i o n ( m 3 / m o n t h )

250 m3/d of fats, oils and greases (FOG) waste

into the anaerobic digesters. About 4.2 GWh of

energy is generated annually from the biogas ofFOG digestion and meets about 15% of the total

energy consumption.

Conclusions


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Conclusions

A water reclamation plant can be designed to treat the

used water to the required standards. But it has to beoperated optimally with minimal use of resources.Energy is a main variable resource used;

Mass flow and balance studies can identify areas of

shortcomings that affect process energy efficiency ofthe water reclamation plant;

Comparison with and benchmarking against plantswith best practices can then be made and

improvements identified; Mass flow and balance is an useful and powerful tool

to improve the process energy efficiency ofwastewater treatment plant.


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Thank You

performance eval and op considerations_wyl_vf

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