Dynamic Process Modeling for Managing Energy Efficiency

Michigan Water Environment Association Annual Conference

June 19, 2017

Richard Beardslee, City of Battle CreekKendra Sveum, Donohue & Associates

Outline

• Battle Creek WWTP

– Energy Evaluation

– Control Strategy

• Stickney WRP

– Energy Evaluation

– Blower Operation

Acknowledgements

Battle Creek WWTP

• M&R

• M&O

• inCTRL Solutions, Inc.

• Carol Naughton & Associates

• EnvironmentalDesign International, Inc.

MWRDGC

• Rich Beardslee

• Chris Dopp

• Carl Fedders

• Kurt Tribbett

• Perry Hart

• Marvin Krause

• Bryan Crawford

• Chris Pratt

Battle Creek Background

Background: Battle Creek

Design capacity 27 mgd

Currently operating at 9 mgd

Significant loadings from food processors and paper

Influent BOD

• 580 mg/L (2013-2014)

• 650 mg/L (2015)

Page 5 | November 12, 2015MWEA

Background: Battle Creek

Page 6 | November 12, 2015MWEA

Process Type: Single-Stage Activated Sludge with Nitrification

Background: Battle Creek

Background: Battle Creek, MI

• Project Drivers

– Energy conservation

– Aged facilities: Blowers cannot be repaired

– Aged facilities: Outdated aeration control

– Process Improvements: Nutrient deficiency issues

– Chemical Savings: Phosphorus control

Battle Creek Evaluation

Dynamic Evaluation

0

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01

4

Air

flo

w (

scfm

)

Airflow Required Airflow Supplied

Blowers

Blower Information New TurboExisting

CentrifugalNo. of Blowers 4 2Firm Capacity 4 1Motor Size (Hp) 350 1000Voltage (V) 480 4160Turndown Method VFD Inlet ThrottlingMaximum Flow (scfm) 7,500 21,000Minimum Flow (scfm) 3,500 13,000

Blower Information Centrifugal PDNo. of Blowers 3 3*Firm No. of Blowers 2 3Motor Size (Hp) 1000 450Manufacturer Hoffman SutorbiltVoltage (V) 4160 460Turndown Method Inlet Throttling NoneMaximum Flow (scfm) 21,000 7,000Minimum Flow (scfm) 13,000 7,000

Operating Range

Remaining centrifugal blower capacity

New turbo blower capacity

Power Comparison

0

5,000

10,000

15,000

20,000

25,000

30,000

35,000

40,000

45,000

50,000

kWh

57% Reduction in Energy

Ammonia-Based DO Control

Controlling Rate of Nitrification with Ammonia-Based DO Control

0

2

4

6

8

10

12

NH

3 (

mg/

L)

NH3 Control DO Control

Beginning of Tank End of Tank

Conceptual Example

Ammonia-Based DO Control

Controlling Rate of Nitrification Based on DO Concentration

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0

Nit

rifi

er

Gro

wth

Rat

e (

Re

lati

ve o

t M

ax R

ate

)

Dissolved Oxygen (mg/L)

Significant impact on growth rate over potential range of DO concentrations

Ammonia Control Loop v2

Blowers

FIT

PIT

DO

DO Control with Air Header Pressure Based Blower Control

To Other Tanks/Passes

Pressure Control Loop

Pass 1

Pass 2

DO Ammonia

DO Control Loop

Ammonia Control Loop

DO Setpoint(s) automatically adjusted to maintain ammonia

concentration setpoint Operator Input: Ammonia Setpoint

Control Clamp: Min/Max Airflow

Ammonia-Based DO Control

Controlling Rate of Nitrification with Ammonia-Based DO Control

0

2

4

6

8

10

12

NH

3 (

mg/

L)

NH3 Control DO Control

Goal Range

For This Example

Slowly Decrease

DO SetpointUntil AmmoniaReading is in

Desired Range

Beginning of Tank End of Tank

Conceptual Example

Probe

Stickney WRP Background

Stickney WRP

Average Primary Effluent

Flow: 787 mgd

BOD5: 155 mg/L

NH3-N: 17 mg/L

TP: 7.67 mg/L

• Average Secondary Effluent

– BOD5: 7.74 mg/L

– NH3-N: 0.57 mg/L

– TP: 1.4 mg/L

– TSS: 5 mg/L

Whole Plant Model

Stickney Evaluation

Aeration System Model

Air Demand Distributions

0

100,000

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700,000

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

Air

flo

w (

scfm

)

Total Airflow Data DO Control Ammonia Control

Aeration Blowers

Blower Number Type

Min(psig)

Max(psig)

Min(scfm)

CurrentMin

(scfm)Max

(scfm)

4 - 7 Axial Flow 7.1 8.1 165,000 210,000 244,000

3 Centrifugal - - 39,000 - 75,000

2* Centrifugal 7.1 8.1 92,500 - 186,000

Blower Operating Ranges

Dynamic Process Modeling for Managing Energy Efficiency

Michigan Water Environment Association Annual Conference

June 19, 2017

Richard Beardslee, City of Battle CreekKendra Sveum, Donohue & Associates