Food Waste Co-Digestion Full-Scale

Demonstration at Newtown Creek WRRF

NYWEA 91st Annual Meeting and Exhibition

Session 20 | Resource Recovery Solutions | February 6th, 2019

Mikael Amar – NYC DEP

Jane Atkinson Gajwani – NYC DEP

Robert Sharp – Manhattan College

James Ecker – Waste Management

2

Landfill Methane

WRRF Fugitive Nitrous Oxide

Cars, Trucks, Marine Vessels, Helicopters

Distillate Fuels, Kerosene, Propane

Utility Steam

Natural Gas

Purchased Electricity

WRRF ADG - Beneficial Use

WRRF ADG - Flared

WRRF ADG - Fugitive

Drivers for Change

• OneNYC + Paris Climate Agreement Goals:

o Energy- and carbon-neutral wastewater

resource recovery facilities by 2050

o 100% beneficial use of biosolids and 90%

reduction in landfilled food waste by 2030

(Zero Waste “ZW” to landfills)

• DEP’s GHG and Energy Footprints:

2nd largest municipal emitter of GHG 3rd largest municipal energy consumer

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1

2

3

4

5

6

Trill

ion

Btu

Site Energy Usage by Fiscal Year

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100

200

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400

500

600

700

800

10

00

mtC

O2

e

GHG Emissions by Fiscal Year

3

Drivers for Change (cont.)

• Local Laws influencing DEP co-digestion

policy:

o Local Law 66 of 2014 (One City Built to

Last) and Executive Order 26 of 2017

▪ Codifies 80x50 + ECNx50

o Local Law 146 of 2013 (Commercial

Organics Law)

▪ Authorizes DSNY to require certain

food service establishments to recycle

organic waste

o Introduction 844 of 2018

▪ Codifies 0x30

• Other citywide initiatives influencing

DEP co-digestion program:

o Off-site pre-processing of source-

separated organics

0

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Cu

mu

lati

ve N

um

ber

of

Loca

l Law

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Sustainability Local Laws in NYC Impacting Water Supply and

Wastewater Resource Recovery

Waste Reduction Energy & Carbon

Green Buildings Landscaping & Stormwater

Water Environmental Justice

Air & Noise Climate Change

Hazards

4

Why Food Waste Co-Digestion

• Meet zero waste, energy-neutrality, and carbon-neutrality goals:

o Divert food waste from landfills to beneficial use (additional digester gas)

o Supplement digester gas production shortfall for energy neutrality

o Provide excess digester gas volumes for biogas-to-grid system

o Improve nutrient value of biosolids

Note: Baselines reflect FY18 electricity purchases. Generation potential assumes 40% cogeneration engine fuel-to-electrical-power efficiency.

0

50

100

150

200

250

300

350

400

450

26W BB CI HP JA NC NR OB OH PR RH RK TI WI

Bill

ion

Btu

s

Electricity Generation Potential of NYC DEP's Anaerobic Digester Gas

Baseline (from Electricity only)

Potential - Energy Generation (Off-site Use)

Potential - Energy Generation (On-site Use)

Planned - Energy Generation (Off-site Use)

Planned - Energy Generation (On-site Use)

Currently Used as Power

5

Why Food Waste Co-Digestion (cont.)

• Potential source of cost offsets in the form of tipping fees

• Co-digestion kinetics:

o Digestibility of different feedstock

o Off-site pre-treatment needed to increase biodegradability

o Methane potential, quantity, and quality

CO2

50%

CH4

50%

CO2

29%CH4

71%

CO2

38%

CH4

38%

NH4

18%

H2S6%

Sugars

Fats

Proteins

6

Bench-Scale Co-Digestion Demonstration

Observations:

• Food waste addition significantly increases total energy value of biogas

• Increase in ammonia and a reduction in volatile acids

• Stable process based on pH, CH4 generation, % VSR, and VA/Alk

• No foaming or process issues even at 25% food waste replaced

• Small impacts on gas quality – function of source

Reactor

A

Control

Reactor

B

Reactor

C

7

Full-Scale Co-Digestion Demonstration

Objective: Determine full-scale energy benefits of food waste (Engineered Bio-

Slurry® or “EBS®”) co-digestion while evaluating whole-plant impacts, including:

• Digestion process: performance, stability, and upsets

• Fate of solids, including biosolids dewatering, quantity, quality, and beneficial

reuse of biosolids

• Return streams: ammonia content, struvite potential

4 Control Digesters

3 Test Digesters

02468

101214161820222426283032

10

00

Gal

lon

s Pe

r D

ay

Total EBS® Feed Rate

Phase 1 IntensiveSampling @ 13% VSLoad

Phase 2 IntensiveSampling @ 19% VSLoad

EBS Feed Rate(30-day rolling avg.)

EBS Feed Rate(Forecasted)

8

Phase 1 Digester Performance

Food Waste Loading

• Engineered Bio-Slurry (EBS®) injected at around 20,000 gallons per day

during intensive sampling period.

• EBS® accounted for ~13% of the VS loading in the test digesters.

0%

5%

10%

15%

20%

25%

17.0

17.5

18.0

18.5

19.0

19.5

20.0

20.5

12/21 12/31 1/10 1/20 1/30 2/9 2/19 3/1 3/11

% EBS VS Loading

1000 Gallon / day Food Waste Loading

Food Waste Feed (1000 Gal/day) % VS Loading EBS

9

0

10

20

30

40

50

60

12/21 12/31 1/10 1/20 1/30 2/9 2/19 3/1 3/11

10

00

lb

sV

S /

da

y

Average VS Loading (1000 lbs VS / day)

Control Test

Phase 1 Digester Performance (cont.)

Total Volatile Solids Loading (TWAS + EBS®)

• Test digesters had on average ~150% more total VS load.

• Test digesters had more VS load variability due to variable TWAS flow.

• Test digesters had ~33% lower SRT.

10

40%

45%

50%

55%

60%

65%

70%

12/21 12/31 1/10 1/20 1/30 2/9 2/19 3/1 3/11

% V

SR

Average VS Reduction (%)

Control Test

Phase 1 Digester Performance (cont.)

% Volatile Solids Reduction

• EBS® VSR was ~72% assuming control digesters’ (all TWAS) VSR was ~56%

and test digesters’ (TWAS + EBS®) VSR was ~58%.

11

Phase 1 Digester Performance (cont.)

Gas Production

• Test digesters produced ~60% more biogas.

• Test digesters experienced most variable TWAS VS loading.

• Individually, test digesters experienced variable EBS® and TWAS distribution.

• Test digesters removed ~160% more in lbs VS.

0

100

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400

500

12/11 12/31 1/20 2/9 3/1 3/21

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00

Cu

bic

Feet

/ D

ay

Avg. Gas Production per Digester(1000 ft3 / day)

Control Test

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00

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s V

SR

Avg. VS Reduction(1000 lbs / day)

Control Test

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0

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Cu

bic

Feet

Gas /

lb

sV

SR

Average Specific Gas Production (ft3 gas / lbs VSR)

Control Test

Phase 1 Digester Performance (cont.)

Specific Gas Production vs. VS Reduction

• Test digesters had about equal specific gas production vs. VSR as control.

• Specific gas production vs. VSR was not temperature related (all at ~100°F).

13

Phase 1 Digester Health

Foaming Potential & Instability

• Test digesters had ~13% lower foaming potential and produced less unstable

foam.

1.5

2.0

2.5

3.0

3.5

4.0

4.5

5.0

5.5

6.0

11/11 12/31 2/19 4/10

Sta

ble

Fo

am

Rati

o

Average Foaming Potential

Control Test

1.5

2.0

2.5

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3.5

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4.5

5.0

5.5

6.0

11/11 12/31 2/19 4/10

Un

sta

ble

Fo

am

Rati

o

Average FoamInstability

Control Test

Foam testing equipment

14

Phase 1 Digester Health (cont.)

VA / Alk Ratio

• Test digesters had ~14% higher VA/Alk ratio.

0.015

0.017

0.019

0.021

0.023

0.025

0.027

0.029

0.031

12/11 12/21 12/31 1/10 1/20 1/30 2/9 2/19 3/1 3/11

VA

/ A

lk

Average VA / Alk Ratio

Control Test

15

Phase 1 Gas Quality

Gas Composition (CH4 Content)

• Test digesters produced ~1% higher methane content.

60.5

61.0

61.5

62.0

62.5

63.0

63.5

64.0

64.5

12/11 12/21 12/31 1/10 1/20 1/30 2/9 2/19 3/1 3/11

Meth

an

e (

%)

Average CH4 Purity (%)

Control Test

16

Phase 1 Gas Quality (cont.)

Gas Composition (H2S Content)

• Test digesters produced up to 17% higher H2S content.

• Test digesters also had higher VS loading and lower SRT.

70.0

80.0

90.0

100.0

110.0

120.0

130.0

140.0

12/11 12/21 12/31 1/10 1/20 1/30 2/9 2/19 3/1 3/11

H2S

(p

pm

)

Average H2S (ppm)

Control Test

17

Phase 1 Gas Quality (cont.)

Siloxanes

• Test digesters produced 12% lower siloxanes.

Siloxane Control (ppb) Test (ppb)

Decamethylcyclopentasiloxane-D5 59 43

Decamethyltetrasiloxane-L4 -- --

Dodecamethylcyclohexasiloxane-D6 -- --

Dodecamethylpentasiloxane-L5 -- --

Hexamethylcyclotrisiloxane-D3 7.6 --

Hexamethyldisiloxane-L2 6.9 --

Octamethylcyclotetrasiloxane-D4 130 64

Octamethyltrisiloxane-L3 7.9 --

Trimethyl silanol 1500 1400

Total Siloxanes 1711 1507

18

Phase 1 Digestate Quality

Ammonia, sCOD, and Phosphorus

• Test digesters produced about equal ammonia concentrations as control.

• Test digesters produced ~19% higher concentration of sCOD.

• Test digesters produced ~17% lower concentration of soluble TP.

1978

749

291

1943

889

249

0

500

1,000

1,500

2,000

2,500

NH3-N (mg/L) sCOD (mg/L) Soluble TP (mg/L)

Co

nce

ntr

ati

on

(m

g /

L)

Ammonia, sCOD, and Phosphorus

Control Test

19

Phase 1 Summary of Findings

• 13% increase VS loading from EBS® increased biogas yield by 60%.

• Slight differences in biogas quality.

• No significant impacts to digester health or chemistry – and several benefits.

Digester% TS

(Feed)

% VS

(Feed)

% TS

(EBS)

% VS

(EBS)

% TS

(Digest-

ate)

% VS

(Digest-

ate)

QEBS

(1000

GPD)

% VS

Loading

(EBS)

Control5.77%

(0.56%)

83.6%

(1.62%)-- --

2.51%

(0.02%)

68.9%

(0.12%)-- --

Test6.47%

(0.84%)

84.6%

(1.29%)

12.5%

(0.39%)

90.5%

(0.25%)

2.69%

(0.02%)

69.5%

(0.23%)

19.1

(0.77)

12.9%

(2.09%)

DigesterVS

Loading% VSR

VSR

(1000

lb / day)

Gas Produced

(1000 ft3 gas

per day)

ft3 gas per

lbs VS Load

ft3 gas per

lbs VSR

Control28.8

(4.99)

56.4%

(5.07%)

17.9

(3.76)

232

(29.6)

8.18

(1.00)

13.6

(2.11)

Test43.4

(5.53)

58.3%

(4.06%)

27.9

(4.34)

362

(41.9)

8.40

(0.85)

13.4

(1.52)

20

Full-Scale Demonstration Phase 2

• Beginning next week at 30,000 gpd of EBS®

co-digested per day through March 2019.

• Additional investigation:

o Microbial ecology changes: 16sRNA (DNA)

sequencing to characterize the microbial

community of control and test digesters.

o Biomethane potential (BMP) test: provide

supplemental data on the potential for food

waste to increase specific gas production,

biogas methane content, and threshold levels

of food waste addition specific for Newtown

Creek’s digestion process.

o Biosolids characteristics and alignment

with end-use options

o Off-gas testing: from EBS® storage tank

odor control system.

o Inert solids and grit analysis

Incubation unit

Absorption unit

Gas volume measuring unit

BMP System

21

Food Waste Co-Digestion Program Considerations

• Food waste availability, quality

o DSNY policies – Rollout timing

+ competition with composting

and on-site treatment

o Contamination and yard waste

• Feed-in station, WRRF design

o Preventive maintenance

schedules

o Training and SOPs

o Odor control

o Mixing (wet wells, feed-in

station, digesters)

o Digester gas metering and

outlets (foaming)

• Staff and knowledge transfer

Residual Detail

Food Wastewith < 10%

contamination

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Next Steps

• Continue and conclude Phase 2

• Identify additional feedstocks

o Scum & FOG

• Identify future locations

• Share research and best

practices with industry

• Develop commercial-scale

program

o Circular economy of organics

o 100% biosolids beneficial use

o Closing the loop with biogas-

to-grid

o Energy and carbon neutrality

EBS® Digesters & EBS®

storage tank at Newtown Creek

EBS® hauler making delivery

to Newtown Creek feed-in

station

23

Newtown Creek RNG and Organics Addition

• Enough capacity to digest up to 500 tpd of food scraps:

o 15% of the city’s residential organic waste

o 8% of the city’s total food waste

• Excess digester gas conditioned in renewable natural biogas-to-grid system

offsets GHG equivalents of:

o Heating needs of 2,500 homes

o Gasoline usage of 3,000 vehicles

Current production and in-plant use based on pre-co-digestion program data.

Organics ADG production estimated based on 13% VS loading in all active digesters.

ADG

Production

On-Site

Beneficial Use

Off-Site

Beneficial Use

24

Circular Economy of Organics

NYC DEPWastewater

ResourceRecoveryFacilities

Waste TransferStation

Agriculture

Natural GasUtilities

Residences& Schools

CommercialEstablishments

CommercialHaulers

NYC Departmentof Sanitation

WWT Process Digesters

Compost

Bio solids

Biogas

Food Waste(Source-

SeparatedOrganics)

Food Waste(Source-Separated

Organics)

Food Bioslurry

Food

Wastewater

Image Credit: NYC DEP Office of Energy & Resource Recovery Programs

25

The Authors Would Like To Acknowledge

Extra Slides

27

Phase 1 Digester Performance

Specific Gas Production vs. Applied VS Load

• Test digesters had ~2% higher specific gas production per VS load.

4

5

6

7

8

9

10

11

12/21 12/31 1/10 1/20 1/30 2/9 2/19 3/1 3/11

10

00

Cu

bic

Feet/

Day

Avg. Spec. Gas Production (ft3 / lbs VS Load)

Control Test

28

Phase 1 Digestate Quality

Digestate % Total Solids

• Test digesters produced digestate with ~8% higher TS content.

• Dewatering tests indicated no net impact in biosolids production at 20,000

gallons per day EBS® loading rate.

2.45%

2.50%

2.55%

2.60%

2.65%

2.70%

2.75%

2.80%

12/21 12/31 1/10 1/20 1/30 2/9 2/19 3/1 3/11

To

tal S

olid

s (

%)

% TS Digestate

Control Test