a.k.a. NUTRIENT REMOVAL OPTIMIZATION

Nitrate Analyzers, Supplemental Carbon Addition, and Treatment Plant Modeling Improves Nitrogen Removal without Capital Expenditures at UAJA

SWOWEA – Young Professional Award 2012

Will Martin – Hazen and Sawyer, P.C. Mark D. Strahota, PE – Hazen and Sawyer, P.C. Brian L. Book, PE – Hazen and Sawyer, P.C. Theresa Bruton, PE – Hazen and Sawyer, P.C. Brad Hice, PE – Environmental Operating Solutions, Inc. David A. Smith – University Area Joint Authority

Background

UAJA’s Spring Creek PCF

Current Plant Configuration

Screens

Figure 1. Spring Creek WPCF Schematic – Sampling Locations

Grit

Removal

BNR Tanks

RAS

NRCY

Tertiary

Filters

U.V.

Primary

Clarifiers

Final

Clarifiers

Centrifuges

Composting

WAS

To AWT

AWT

Reject

Water

Maintenance

Biofilter

From AWT

AlumFilter

Backwash

Aerated Solids

Storage

Mix

Tank

Centrate

Plant Drain

Pump Station

History of UAJA’s Beneficial Reuse

• Preliminary Study in 1991

• Issues related to “High Quality Cold Water Fishery” status and temperature

• 8 year study resulted in Beneficial Reuse

• UAJA Project Management Team began to work on plant expansion concepts

Nutrient Removal Becomes Factor

• Some level of TN removal desired relative to beneficial reuse

• Initial efforts focused on TN of 10 mg/l

• A2O process implemented as upgrade to AO

• CBTS enters the conversation

History of PA Nutrient Limits

• 2000: PA Governor Tom Ridge signs Chesapeake Bay Compact (2B lbs/d TN)

• 2005: Mass-based annual limit based on average daily flow and 8 mg/L TN, 1 mg/L TP

• 2007: Change to permit flow, 6 mg/L, 0.8 mg/L • 2010: Tier 1 Compliance (including UAJA)

Design adjusted for 6 mg/L TN Carbon addition trial Credit Trading Program

• Tier 2 Plants in 2012, Tier 3 in 2014

Nutrient Removal Performance

• 2010: Dry, warm year; decent TN results

• Winter 2010 - Spring 2011 Cold, wet winter

Lost nitrification in January 2011

Denitrification slow to start

By April, became clear that TN will be over permit

Trial period with supplemental carbon

Contract with EOS for MicroC Glycerin and Hach NOX-N meters installed as loaner

Study Approach

MicroC Glycerin Background

• Supplemental carbon source as an electron donor for denitrification

• Alternative to methanol

• COD = 1,040,000 mg/L

MicroC Glycerin Initial Results

0

2

4

6

8

10

12

NO

x C

on

cen

trat

ion

(m

g/L)

Anoxic Influent NOx (mg/L) Anoxic Effluent NOx (mg/L)

MicroC GlycerinTM Feed Begins

Feed point adjusted from IDB to Anoxic Zone 2

June 2011 Plant Evaluation

• Plenty of capacity; some recommendations:

• Boost RAS to approximate an MLE configuration

(** note Bio-P removal not a goal)

• Increase MLSS

• Increase internal nitrogen recycle (NRCY)

• Preliminary indication that system is carbon limited and DO inhibited

• Try carbon feed to Anaerobic Zone 1

Biological Process

Primary

Effluent

RAS Anaerobic 1

Anaerobic 2 Anaerobic 3

Anaerobic 4

Anoxic 1 Anoxic 2

Aerobic 1Aerobic 2

Aerobic 3NRCY

Pumps

DO

DO

NO3

NO3

XXProbe

location

Mixer

location

DO will be measured

in current sampling

locations.

Biological Process

Calibration of BioWin™ Model

• Historical data analysis

• Sampling program (August 2011) to modify and/or confirm BioWin default model parameters

Process Grab Samples

Primary

Effluent

RAS Anaerobic 1

Anaerobic 2 Anaerobic 3

Anaerobic 4

Anoxic 1 Anoxic 2

Aerobic 1Aerobic 2

Aerobic 3NRCY

Pumps

DO

DO

NO3

NO3

XXProbe

location

Mixer

location

PROCESS GRAB

DO will be measured

in current sampling

locations.

Process Sample Results

• Train 1 Nitrogen Profile

0

5

10

15

20

25

30

35

Co

nce

ntr

atio

n (

mg/

L)

NH3-N AM

NO3-N AM

NH3-N PM

NO3-N PM

NO3 Probe AM

NO3 Probe PM

Process Sample Results

• Chemical Oxygen Demand (COD)

0

50

100

150

200

250

Co

nce

ntr

atio

n (

mg/

L)

Train 1 AM Avg

Train 3 AM Avg

Train 1 PM Avg

Train 3 PM Avg

BioWin™ Model

• Used as an additional tool to optimize nutrient removal through simulated seasonal changes and variations in influent flows and loadings

Summary of Recommendations

• Keep carbon feed location in Anoxic Zone 1

• Increase NRCY flow to 450%

• Increase carbon feed to 700 gpd

• Capital improvements for consideration:

Permanent carbon storage and feed

Automated carbon addition

Swing zone in current aerobic zone

Internal recycle feed to anaerobic zone

Results of Study

Influent Conditions: BOD

0

100

200

300

400

500

600

700

800

0

5,000

10,000

15,000

20,000

BO

D C

on

cen

trat

ion

(m

g/L)

BO

D (

pp

d)

Influent BOD (ppd) Influent BOD (mg/L)

30 per. Mov. Avg. (Influent BOD (ppd)) 30 per. Mov. Avg. (Influent BOD (mg/L))

PENN STATE FALL SEMESTER BEGINS

~30% Increase in BOD ppd

Influent Conditions: NH3-N

0

10

20

30

40

50

60

70

80

0

500

1000

1500

Co

nce

ntr

atio

n (

mg/

L)

NH

3-N

(p

pd

)

Influent NH3N (ppd) Influent NH3N (mg/L)

30 per. Mov. Avg. (Influent NH3N (ppd)) 30 per. Mov. Avg. (Influent NH3N (mg/L))

PENN STATE FALL SEMESTER BEGINS

~90% Increase in NH3-N ppd

Results

0

2

4

6

8

10

12

14

16

18

20

0

100

200

300

400

500

600

700

800

LB C

OD

/LB

NO

x-N

Rem

ove

d

Effl

uen

t N

Ox-

N (

PP

D)

or

Mic

roC

Usa

ge (

gpd

)

Aerobic Effluent Nox (PPD), 7-Day Average MicroC Feed (gpd) lbs COD/lbs N Removed - 7 Day Average

CARBON FEED TO ANOXIC ZONE 1

CARBON FEED TO ANAEROBIC ZONE 1

NRCY=350% NRCY=400%

PENN STATE FALL SEMESTER BEGINS

NRCY=450%

CARBON FEED TO ANOXIC ZONE 1

Results (cont.)

0

100

200

300

400

500

600

700

800

900

1000

0

1

2

3

4

5

6

7

8

9

10

Mo

nth

ly A

vg M

icro

C G

lyce

rin

Usa

ge (

GP

D)

Mo

nth

ly A

vg A

ero

bic

Eff

flu

ent

NO

x-N

(m

g/L)

Aerobic Effluent Nitrate Avg Supplemental Carbon Use

~40% Reduction in NOX-N Concentration

~30% Increase in Carbon Addition

Influent NH3-N Increases by ~90% in late August 2011

Results in Terms of $

$0.00

$0.50

$1.00

$1.50

$2.00

$2.50

$ p

er P

ou

nd

of

N R

emo

ved

$2.40 per Gallon $2.00 per Gallon

CARBON FEED TO ANOXIC ZONE 1

CARBON FEED TO ANAEROBIC ZONE 1

NRCY=350%

NRCY=400%

PENN STATE FALL SEMESTER BEGINS

NRCY=450%

CARBON FEED TO ANOXIC ZONE 1

Results in Terms of $ (cont.)

• With a $0.50/lb TN reduction in cost of carbon through optimization, UAJA could save up to $800/day

• Pacing carbon feed based on influent nitrogen could result in significant savings

• UAJA can target plant performance for nitrogen removal based on credit trading market

Conclusions and Additional Discussion

Study Conclusions

• Decrease in effluent TN concentration of about 40% using only process changes (no capital costs)

• With limited TN data, cost of implementation was in the range of $1-2 per pound of NOX-N removed

• Price similar to previous experience with glycerin supplemental C sources ($2 per pound of TN - previous Hazen and Sawyer studies)

Study Conclusions

• Glycerin-based carbon supplements are safe and efficient No specialized biological population

No flammability-related safety precautions as with methanol

Cost effective

• Some adjustments may be needed in dosing point and feed rate BioWin simulations could help preparation for

changes

Study Conclusions

• More stringent permit limits = consideration of varying influent conditions and biological population

BioWin™ modeling an important tool

Good practice to “bank” credits in case of storm event or other potential overrun of mass-based permit limit

Lessons Learned

• Keep an accurate record of changes

• Only change one thing at a time

• Be prepared for increased laboratory analysis

• Collect historical TKN data

Future Considerations

• Ethanol production wastewater as carbon supplement?

• WERF cold weather BNR study

Questions

Hazen and Sawyer, P.C. 11311 Cornell Park Drive

Suite 135

Cincinnati, Ohio 45242

Phone: (513) 469-2750

Mark D. Strahota, PE

mstrahota@hazenandsawyer.com

Will Martin

wmartin@hazenandsawyer.com