Post on 07-Aug-2020
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
-
1
2
3
4
5
6
Trill
ion
Btu
Site Energy Usage by Fiscal Year
-
100
200
300
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
10
20
30
40
50
60
70
80
90
100
Cu
mu
lati
ve N
um
ber
of
Loca
l Law
s
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
200
300
400
500
12/11 12/31 1/20 2/9 3/1 3/21
10
00
Cu
bic
Feet
/ D
ay
Avg. Gas Production per Digester(1000 ft3 / day)
Control Test
0
5
10
15
20
25
30
35
40
12/11 12/31 1/20 2/9 3/1 3/21
10
00
lb
s V
SR
Avg. VS Reduction(1000 lbs / day)
Control Test
12
0
2
4
6
8
10
12
14
16
18
20
12/21 12/31 1/10 1/20 1/30 2/9 2/19 3/1 3/11
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
3.0
3.5
4.0
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
22
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