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93 rd Annual Fall Conference. Embassy Suites Charlotte | Concord, NC | November 10-13 | 2013. Sustainable Supplemental Carbon Sources. Hunter Long 1 , Katya Bilyk 1 , Wendell Khunjar 1 Jeff Nicholson 2 , Bill Balzer 2 , Charles Bott 2 James Grandstaff 3 Steven Chiesa 4 Jared Alder 5

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93rd Annual Fall Conference

Embassy Suites Charlotte | Concord, NC | November 10-13 | 2013

  • Sustainable Supplemental Carbon Sources

  • Hunter Long1, Katya Bilyk1, Wendell Khunjar1

  • Jeff Nicholson2, Bill Balzer2, Charles Bott2

  • James Grandstaff3

  • Steven Chiesa4

  • Jared Alder5

  • 1Hazen and Sawyer

  • 2HRSD

  • 3Henrico County DPU

  • 4Santa Clara University

  • 5OpenCEL


Outline
Outline

  • Nansemond TP Overview

    • Co-Fermentation Pilot

    • Results and Discussion

    • Future Work

  • Henrico County WRF Overview

    • OpenCEL Pilot

    • Results and Discussion

    • Future Work

  • Conclusions and Lessons Learned


Nansemond treatment plant suffolk va
Nansemond Treatment PlantSuffolk, VA

  • 30 mgd Design Flow

  • 5-StageBardenpho

  • Annual Average TN (5.0 mg/L) and P (1.0 mg/L) goals


Local conditions

Low sCOD:TKN PCE, high industrial load

Waste methanol: $1,800/d for denitrification

EBPR preferred over chemical P precipitation due to an Ostarastruvite reactor on site

Primary Solids are pumped at around 340,000 gpd (10 dT/day)

Grease Trap Waste (GTW) haulers regularly discharge 5,600 gpd on average (0 to 15,000 gpd)

Additional 2,000 – 9,000 gpd GTW could be diverted from other facilities

Low electrical energy cost does not justify installation of CHP, co-digestion of GTW is not needed

Local Conditions


Study overview
Study Overview

  • PS and GTW Fermentation:

    • Produce onsite carbon for denitrification

    • Offset supplemental carbon purchase

    • Remove GTW from NTP’s mainstream process

    • Enhance biological phosphorus removal

  • Pilot Objectives:

    • Determine VFA and rbCOD production from GTW and PS

    • Determine optimal ratio of GTW:PS (fermenter) and GTW:ADS (blend tank)

    • Evaluate effect of temperature and SRT on fermentation




Primary sludge feed characteristics
Primary Sludge Feed Characteristics

tCOD:TKN = 45.7 sCOD:TKN= 1.66

tCOD:TP= 205.6 sCOD:TP = 7.44


Grease trap waste feed characteristics
Grease Trap Waste Feed Characteristics

tCOD:TKN = 225 sCOD:TKN = 18.1

tCOD:TP= 2,298 sCOD:TP = 185.2


Primary sludge treatment train
Primary Sludge Treatment Train

  • Impeller Mixed

  • 200 rpm

  • 30 cm (12”) impeller

Elutriation

  • Gravity Thickener

  • 0.34 m3 (90 Gallon)

  • HRT: 9 hr

  • Underflow: 2% TS

  • Fermenter

  • Working Volume: 300 Gallon

  • HRT: 24 hr

  • TS: 1.4%

  • pH: 5.3-5.8

  • ORP: -350 - -500 mV

Recycle Pump

Waste Pump


Grease trap waste treatment train
Grease Trap Waste Treatment Train

Blend Tank - 5 gallons

Hydrolyzing lipids

40% GTW & 60% ADS (v:v)

HRT: 7-10 hr

Pump Mixed

pH: 5.6 - 5.9

Headspace Gas:

13% Methane

70 % CO2

17% Bal

Wet Tip Gas Meter


Operating criteria
Operating Criteria

Fermenter

Blend Tank


Evaluation criteria

Fermenter pH

pCOD conversion to sCOD

Effluent sCOD (lbs/day)

Effluent VFA (lbs/day)

Evaluation Criteria


Pcod conversion summary
pCOD Conversion Summary

2.75 day

26-30 C

2 day

25-28 C

5 day

19-25 C

5 day

19-22 C

6.5 day

17-20 C


Incremental gtw pcod conversion
Incremental GTW pCOD Conversion

15 minute blend tank SRT

PS + ADS + GTW

9 hour blend tank SRT

ADS + GTW


Incremental gtw pcod conversion1
Incremental GTW pCOD Conversion

13 hour blend tank SRT

ADS + GTW


Scod and vfa summary
sCOD and VFA Summary

lbs/day

lbs/day



Conclusions

6 to 14% of feed Primary Sludge pCOD can be converted to sCOD

VFAs generally make up 50% to 70% of effluent sCOD

A short HRT blend tank with 20:1 GTW:ADS allowed for an incremental degradation of up to 6%

A longer HRT blend tank with 7:10 GTW:ADS ratio allowed up to 20% incremental degradation of grease trap waste

Unknown whether grease degradation comes at the expense of some primary sludge degradation

PS and GTW is expected to offset ~50% of facility supplemental carbon demand

Conclusions


Next steps

Continue blend tank modifications to determine effect on LCFA degradation

Possible staged fermentation

Bench Scale SBRs to determine fermentate value as supplemental carbon source

Denitrification

Biological Phosphorus Removal

Business Case Evaluation

Next Steps


Henrico county water reclamation facility
Henrico County Water Reclamation Facility LCFA degradation

75 mgd Facility

Low TN and TP Limits


Henrico county wrf current operations
Henrico County WRF Current Operations LCFA degradation

  • GBT WAS thickening

  • Blended feed to digesters

  • BFP dewatering

  • Cake storage on site

  • Glycerol product used for denitrification carbon source

Hydrogen

Oxygen

Carbon


What is opencel
What is LCFA degradationOpenCEL?


Opencel system
OpenCel LCFA degradation System

Images: OpenCel


Opencel theory
OpenCel LCFA degradation Theory

  • Focused electrical pulse treatment

    • Cyclic exposure to positive and negative charges weakens the cell wall

    • Eventually the cyclic forces cause cell rupture and release of internal contents


Opencel impacts
OpenCel LCFA degradation Impacts

Images: OpenCel


Pilot testing goals
Pilot Testing Goals LCFA degradation

  • Determine chemical and physical characteristics of TWAS before and after FP treatment.

  • Characterize the short-term impactof FP treated TWAS on denitrification activity.

  • Characterize the long-term impactof FP treated TWAS on denitrification activity.

  • Characterize the impact of FP treated TWAS addition on nutrient removal performance at HCWRF.

Oxygen

Nitrate

Denitrification

Carbon

Nitrification

Oxygen

Nitrite

NitrogenGas

Ammonia


Experimental configuration
Experimental Configuration LCFA degradation


Opencel container
OpenCel LCFA degradation Container


Focused pulse treatment releases soluble COD that can be used for denitrification

  • Sampled on two occasions in January and February 2013

ssCOD Yield ~ 7 to 9 % of TS


Short term batch test data suggests that treated twas has a superior nitrate reduction rate
Short term batch test data suggests that treated TWAS has a superior nitrate reduction rate

  • Note that non-treated TWAS also has higher nitrate reduction rate

31


Full scale cod characterization experiments were performed
Full-scale COD characterization experiments were performed superior nitrate reduction rate

  • Samples collected and filtered onsite immediately through 1.2 mm filters

  • Value were cross-checked with independent measurements

Yield from initial full-scale experiments = 0.01 mg ssCOD/mg TS

Predicted yield from bench-scale experiments = 0.09 mg ssCOD/mg TS

OpenCel working to increase ssCOD yield from full-scale pilot


Experimental configuration scenario 1
Experimental Configuration Scenario 1 superior nitrate reduction rate

30% of glycerol dose

  • Currently Henrico adds glycerol to pre-anoxic and post-anoxic zones for denitrification

  • OpenCel treated TWAS will be fed to the pre-anoxic zone

4.87 mgd PE

70% of glycerol dose

RAS


Experimental configuration scenario 2
Experimental Configuration Scenario 2 superior nitrate reduction rate

50% of glycerol dose

4.87 mgd PE

50% of glycerol dose

RAS


Implications for pilot testing
Implications for pilot testing superior nitrate reduction rate

  • Assume yield is 0.09 mg ssCOD/mg TS

  • 20 gpmOpenCel flow

  • Assume yield is 0.01 mg ssCOD/mg TS

  • 20 gpmOpenCel flow


Additional considerations
Additional Considerations superior nitrate reduction rate

  • FP treated TWAS will return significant TSS

  • MLSS will increase if wasting is not increased

  • Increased wasting will reduce cell residence time

    • May impact nitrification

  • TWAS recycle can act as bioaugmentation if cells are not inactivated


Insights from process modeling
Insights from Process Modeling superior nitrate reduction rate

  • At 23 deg C and 15 gpmOpenCel and assuming no biomass inactivation in the OpenCel stream

    • Fourfold increase in WAS rate is needed to maintain reasonable mixed liquor concentration

    • Despite this increase in WAS rate and corresponding SRT reduction, nitrification is not significantly impacted

    • Bioaugmentation from OpenCel stream is crucial for helping to maintain complete nitrification

  • At 12 deg C and 15 gpmOpenCel and assuming no biomass inactivation in the OpenCel stream

    • Fourfold increase in WAS rate is still needed to maintain reasonable mixed liquor concentration

    • Nitrification is not significantly impacted

    • Bioaugmentation from OpenCel stream helps maintain nitrification at lower temperatures


Insights from process modeling1
Insights from Process Modeling superior nitrate reduction rate

  • At 23 deg C and 15 gpmOpenCel and assuming 100% biomass inactivation in the OpenCel stream

    • Fourfold increase in WAS rate is needed

    • Nitrification is not significantly impacted at 23 deg C

  • At 12 deg C and 15 gpmOpenCel and assuming 100% biomass inactivation in the OpenCel stream

    • Fourfold increase in WAS rate is needed

    • Nitrification performance is lost at the low temperature

  • It is expected that there will be between 0 and 100% inactivation through the OpenCel process, therefore:

    • Actual impact on nitrification will closely depend on the degree of inactivation as well as the mass of solids that will be recycled


Next steps1
Next Steps superior nitrate reduction rate

  • SBRs, at the HRSD lab, will be used to determine long term impacts of FP treated TWAS on denitrification activity

  • Impact of FP treated TWAS addition on nutrient removal performance at HCWRF will be tested in Spring 2014

  • Business Case Evaluation


Conclusions and lessons learned
Conclusions and Lessons Learned superior nitrate reduction rate

  • Multiple sources of carbon within the wastewater treatment and collection system

  • High chemical costs and low energy costs can lead to GTW utilization or WAS pretreatment for supplemental carbon rather than biogas

    • GTW fermentation would still increase biogas production

      • ~60-85% of GTW COD is retained in wasted sludge

  • Evaluation must account for additional TSS, N, and P in “sustainable” supplemental carbon source


Acknowledgments
Acknowledgments superior nitrate reduction rate


Questions

Hunter Long superior nitrate reduction rate

[email protected]

(919) 833-7152

?

Questions


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