oEPA

Anaerobic Digestion

Facilities Processing

Food Waste in the

United States in 2015

July 2018
EPA/903/S-18/001

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Author
Melissa Pennington, Sustainability Coordinator, EPA Region 3, Philadelphia, PA
Acknowledgements
EPA would like to thank all the facility operators who provided data. This report is based entirely on
information provided by all of you. The response rate to the survey was fantastic, especially considering
that completion of the survey was voluntary. EPA greatly appreciates receiving this valuable data. In
return, we hope that you find the information provided in this report to be useful.
This project would never have gotten off the ground without the outstanding technical support of David
MacFarlane in EPA Region 3's Information Systems Branch. David patiently and expertly assisted with
the design and implementation of the electronic surveys.
Document Review
This document was peer reviewed by:
Debra L. Forman, Ph.D., Information Management Team Leader/Toxicologist, EPA Region 3,
Philadelphia, PA
Anelia Milbrandt, Senior Researcher, National Renewable Energy Laboratory (NREL), Golden, CO
The following team from EPA's Office of Land and Emergency Management, Office of Resource
Conservation and Recovery, also reviewed the document:
Chris Carusiello, Environmental Engineer
Claudia Fabiano, Environmental Protection Specialist
Elana Goldstein, Environmental Protection Specialist
Ellen Meyer, Economist
Andrea Schnitzer, Environmental Protection Specialist
Quality Assurance
EPA conducted a quality assurance review of the data and calculations used to generate the information
in this report. This review was conducted by Sharon D. Kenny, Environmental Engineer, EPA Region 3's
Environmental Assessment and Innovation Division. No errors or inconsistencies were found in the
datasets.
Disclaimer
The anaerobic digestion facilities and their locations are provided for informational purposes only.
Companies mentioned in this database are not certified or approved by US EPA. EPA does not guarantee
the accuracy or completeness of this information.
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Table of Contents
List of Tables	iii
List of Figures	iv
Executive Summary	v
I.	Background	1
II.	Survey Data Collection	2
III.	Results	2
A.	Location Data and Response Rates	2
B.	Processing Capacity	7
C.	Operational Dates	9
D.	Food Waste Processed	10
E.	Non-Food Waste Processed	10
F.	Feedstock Types	11
G.	Feedstock Sources	13
H.	Tipping Fees	15
I.	Pre-processing/De-packaging	16
J. Operational Specifications	17
K. Biogas Production	17
L. Biogas Uses	18
M. Gas Cleaning Systems	21
N. Solid Digestate Uses	22
O. Liquid Digestate Uses	24
IV.	Conclusion	25
Appendix A - Operational Digesters and Co-Digestion Systems	A-l
Appendix B - Survey Questions	B-l
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List of Tables
Table ES-1: Number of Anaerobic Digestion Facilities Confirmed Operational, and Responding to
Survey by Digester Type (2015)	v
Table ES-2: Total Capacity for Processing Food Waste and Total Amount of Food Waste Processed by
Digester Type (2015)	v
Table ES-3: Total Amount of Non-Food Waste Processed by Digester Type (2015)	vi
Table ES-4: Summary of Biogas Data Reported by Digester Type (2015)	vi
Table 1: Number of Anaerobic Digestion Facilities Identified, Operational, and Responding to Survey
by Type (2015)	3
Table 2: States with Operating Anaerobic Digestion Facilities (Confirmed and Non-Confirmed) by
Facility Type (2015)	7
Table 3: Total Capacity for Processing Food Waste via Anaerobic Digestion by Digester Type (2015) ....9
Table 4: Total Amount of Food Waste Processed by Each Digester Type (2015)	10
Table 5: Total Amount of Non-food Waste Processed by each Digester Type (2015)	11
Table 6: Types of Food Waste and Non-Food Waste Feedstocks Processed at Stand-Alone Digesters
(2015)	12
Table 7: Types of Food Waste and Non-food Waste Feedstock Processed at On-Farm Digesters (2015)
	12
Table 8: Types of Food Waste and Non-Food Waste Feedstock Processed at Co-Digestion Systems at
WRRFs (2015)	13
Table 9: Sources of Food Waste and Non-Food Waste Feedstock Processed by Stand-Alone Digesters
(2015)	14
Table 10: Sources of Food Waste and Non-Food Waste Feedstock Processed by On-Farm Digesters
(2015)	14
Table 11: Sources of Food Waste and Non-Food Waste Feedstock Processed by Co-Digestion Systems
at WRRFs (2015)	15
Table 12: Pre-processing/De-packaging at Stand-Alone Digester Facilities (2015)	16
Table 13: Pre-processing/De-packaging at On-Farm Digester Facilities (2015)	16
Table 14: Pre-processing/De-packaging at Co-Digestion Facilities at WRRFs (2015)	16
Table 15: Temperature Range Data for each Digester Type (2015)	17
Table 16: Data on Wet vs. Dry Systems for each Digester Type (2015)	17
Table 17: Summary of Biogas Data Reported by Digester Type (2015)	18
Table 18: Uses of Biogas Produced at Anaerobic Digesters (2015)	20
Table 19: Gas Cleaning Systems at Anaerobic Digesters (2015)	21
Table 20: Solid Digestate Uses (2015)	23
Table 21: Liquid Digestate Uses (2015)	24
Table 22: Data Collection Results for 2015	26
Table 1A: Stand-Alone Anaerobic Digestion Facilities Digesting Food Waste in the U.S
Table 2A: On-Farm Digesters Co-Digesting Food Waste in the U.S	
Table 3A: WRRF Digesters Co-Digesting Food Waste in the U.S	
A-l
A-3
A-4

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List of Figures
Figure ES-1: Confirmed Operating Food Waste Digesting Facilities by State (2015)	vii
Figure ES-2: Survey Respondents by State (2015)	vii
Figure ES-3: Top Five Sources of Digester Feedstock by Digester Type (2015)	viii
Figure ES-4: Top Five Feedstocks Accepted by Digesters Taking Food Waste by Digester Type (2015) viii
Figure ES-5: Top Five Uses of Biogas by Digester Type (2015)	ix
Figure ES-6: Top Five Constituents Removed by Digester Type (2015)	x
Figure 1: Operating Stand-Alone Food Waste Digesting Facilities by State (2015)	4
Figure 2: Operating On-Farm Food Waste Co-Digestion Systems by State (2015)	5
Figure 3: Operating WRRF Food Waste Co-Digestion Systems by State (2015)	6
Figure 4: Operating Food Waste Digesting Facilities by State (2015)	6
Figure 5: Distribution of First Year of Digester Operation by Digester Type	9
Figure 6: Top Five Feedstocks Accepted by Digesters Taking Food Waste by Digester Type (2015)	13
Figure 7: Top Five Sources of Digester Feedstock by Digester Type (2015)	15
Figure 8: Top Five Uses of Biogas by Digester Type (2015)	21
Figure 9: Top Five Constituents Removed by Digester Type (2015)	22
Figure 10: Top Five Uses of Solid Digestate by Digester Type (2015)	24
Figure 11: Uses of Liquid Digestate by Digester Type (2015)	25
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Executive Summary
In 2017, the United States (U.S.) Environmental Protection Agency (EPA) surveyed U.S. operators of
anaerobic digestion (AD) facilities that accept food waste to identify the number of facilities in the U.S.
and their locations, and to learn about their operations. This report is the first of three annual data
collections EPA will make through 2019. This first report covers data for calendar year 2015 and
summarizes data received for three types of anaerobic digestion facilities: (1) stand-alone food waste
digesters; (2) on-farm digesters that co-digest food waste; and (3) digesters at water resource recovery
facilities (WRRFs) that co-digest food waste. Future reports will summarize data for 2016, 2017, and
2018.
EPA determined the number of AD facilities known to accept food-based materials1 by reviewing
publicly available information. Based on this research, EPA offered the survey to all facilities for which
contact information was known. EPA also made the survey available on the Agency's website. EPA then
confirmed the operational status of the facilities through direct contact with operators, a portion of
which provided survey responses (Table ES-1).
Table ES-1: Number of Anaerobic Digestion Facilities Confirmed Operational, and Responding to
	Survey by Digester Type (2015)	
Digester type
Confirmed
Operational
Submitted
Survey
Survey Response
Rate
Stand-alone digesters
58
50
86%
On-farm digesters
18
15
83%
Co-digestion systems at WRRFs
78
72
92%
Total
154
137
89%
Processing Capacity and Amounts in 2015
Based on data submitted by 137 survey respondents, the total processing capacity for food waste and
food-based materials in all three digester types in 2015 was 15,809,647 tons per year and the total
amount of food waste processed in all three digester types was 12,730,657 tons (Table ES-2).
Table ES-2: Total Capacity for Processing Food Waste and Total Amount of Food Waste Processed by
	Digester Type (2015)	
Digester Type
Reported Capacity
(tons per year)
Reported Amount Processed
(tons per year)
Stand-alone digesters
12,563,687
9,828,081
On-farm digesters
210,754
112,879
Co-digestion systems at WRRFs
3,035,206
2,789,697
Total
15,809,647
12,730,657
1 For the purposes of this report, food-based materials include, but are not limited to: food scraps that have been
separated and collected by municipalities from residential sources; food scraps that have been separated and
collected from institutions or venues (e.g., prisons, hospitals, stadiums); food scraps from food preparation at
restaurants, cafeterias, and other food services; plate scrapings from restaurants, cafeterias, and other food
services; fats, oils and grease (FOG); unused food collected from grocery stores (e.g., bakery items, bruised fruit,
items past shelf life); and pre-consumer by-products of the food and beverage processing industries.
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The total amount of non-food waste2 processed in all three digester types combined was 2,219,988,176
gallons and 461,723 tons (Table ES-3).
Table ES-3: Total Amount of Non-Food Waste Processed by Digester Type (2015)
Digester Type
Amount
(liquid)
Amount
(solid)*
Stand-alone digesters
34,341,130 gallons
134,757 tons
On-farm digesters
2,940,000 gallons
2,103 tons
Co-digestion systems at WRRFs
2,182,707,046 gallons
324,863 tons
Total
2,219,988,176 gallons
461,723 tons
* Amounts were reported in liquid and solid units. Because there is no common conversion factor for
non-food waste, these values are separated.
Biogas Production
The total amount of biogas produced at digesters in 2015 was 358,742 standard cubic feet per minute
(SCFM), equivalent to 1,117 MW installed capacity, 8.361 billion kWh per year, or enough energy to
power 684,639 homes for a year.
Table ES-4: Summary of Biogas Data Reported by Digester Type (2015)
Digester type
SCFM*
MW
kWh/yr
(million)
Number of Homes
Powered for One Year
Stand-alone digesters
9,176
29
216
17,781
On-farm digesters
1,979
6
45
3,704
Co-digestion systems at WRRFs
347,587
1,083
8,064
663,812
Total
358,742
1,117
8,317
684,639
* SCFM values are reported by facility operators and added together to get total SCFM for 2015
(358,742). The MW, kWh/yr, and homes powered numbers are calculated using the LMOP interactive
conversion tool. These values are rounded to the nearest whole number, which accounts for the fact that
the column totals may not sum.
These figures likely underestimate actual processing capacity, food waste and non-food waste
processed, and biogas production because not all operational facilities provided a survey response.
Thirty-five states had at least one confirmed operating digester (Figure ES-1). States with ten or more
confirmed operating digesters included California (30), Wisconsin (17), Ohio (13) and New York (13).
Figure ES-2 shows the actual number of survey respondents by state.
2 Non-food waste feedstocks include, but are not limited to: mixed yard waste, crop residues, manure, wastewater
solids (sludge), septage, de-icing fluid, lab (or pharma) wastes, paper mill wastes, and crude glycerin.
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Figure ES-1: Confirmed Operating Food Waste Digesting Facilities by State (2015)
Figure ES-2: Survey Respondents by State (2015)
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Operational Specifications and Pre-Processing Activity
In terms of operational specifications, the majority of the digester types were found to be mesophilic
and were wet digester systems. The top pre-processing/de-packaging activity for both stand-alone
digesters and on-farm digesters was manual or mechanized de-packaging, and for co-digestion facilities
at WRRFs, screening for debris or sorting.
Feedstock Sources and Types
Figure ES-3 aggregates the top five feedstock sources by digester type in 2015, and Figure ES-4
aggregates the top five feedstocks accepted by digester type in 2015.
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Figure ES-4: Top Five Feedstocks Accepted by Digesters Taking Food Waste by Digester Type (2015)
viii

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Biogas Uses and Cleaning Systems
Figures ES-5 and ES-6 provide information on biogas uses and cleaning systems. The top use of biogas
among all three digester types was to produce heat and electricity (CHP). The next two highest uses by
digester type were:
•	Stand-Alone Digesters: to produce electricity (sold to the grid), and to fuel boilers and furnaces
to heat other spaces;
•	On-Farm Digesters: to produce electricity (sold to the grid), and to produce electricity used
behind the meter (including net metering); and
•	Co-Digestion Facilities at WRRFs: to fuel boilers and furnaces to heat digesters, and to fuel
boilers and furnaces to heat other spaces.
Over 60% of all digester types reported that they utilize gas cleaning systems. The top constituents
removed for all digester types overwhelmingly included moisture and sulfur. Another notable
constituent removed with gas cleaning systems in co-digestion facilities at WRRFs were siloxanes.
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electricity (CHP) furnaces to heat furnaces to heat electricity (sold to electricity used
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¦ Stand-Alone Digesters ¦ On-Farm Digesters ¦ WRRF Digesters
Figure ES-5: Top Five Uses of Biogas by Digester Type (2015)
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Figure ES-6: Top Five Constituents Removed by Digester Type (2015)
Solid and Liquid Digestate Uses
The top three solid digestate uses by specific digester type were:
•	Stand-Alone Digesters: composted into a reusable/salable product, other, and de-
watered/dried and land applied;
•	On-Farm Digesters: processed into animal bedding, de-watered/dried and land applied, and
composted into a reusable/salable product; and
•	Co-Digestion Facilities at WRRFs: de-watered/dried and land applied, landfilled, and
composted into a reusable/salable product.
The top uses of liquid digestate for stand-alone digesters, on-farm digesters, and co-digestion facilities
at WRRFs, respectively, were: discharged to a wastewater treatment plant, reused as fertilizer via land
application, and recirculated through the digester.
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I. Background
In the United States (U.S.), food is the greatest fraction of material, by weight, in the municipal solid
waste stream. In 2014, approximately 36 million tons of food from the residential, commercial, and
institutional sectors was sent to landfills and combusted for energy, imposing significant economic and
environmental costs.3 To help alleviate these costs, the U.S. Environmental Protection Agency (EPA)
encourages diversion of food waste from landfills, including to anaerobic digestion (AD) facilities.
In April 2014, EPA began building a database of names and locations of AD facilities processing food-
based materials,4 hereinafter referred to as food waste, to better understand more aspects of this
universe (e.g., the current amount of food waste being processed by digesters, available capacity, etc.).
EPA built the original database using publicly available information (e.g., American Biogas Council
project profiles, BioCycle articles, EPA AgSTAR5 database). To enhance the quality and quantity of
available data, EPA was granted authority to collect information through a survey for digesters (see
Appendix B for survey questions). The approval allows EPA to collect data annually for 3 years, from
2017 to 2019, and future reports will summarize data for 2016, 2017, and 2018. The survey itself
requests information about operational characteristics of three types of digesters, and only for those
which process food waste: (1) stand-alone food waste digesters; (2) on-farm digesters that co-digest
food waste; and (3) digesters at water resource recovery facilities (WRRFs) that co-digest food waste.
As part of the research and analysis for this effort, EPA searched for other studies assessing the quantity
and capacity of AD facilities in the U.S. EPA identified an August 2015 report by the Environmental
Research and Education Foundation (EREF), based on 2013 data, entitled "Anaerobic Digestion of
Municipal Solid Waste: Report on the State of Practice." The EREF report inventories the same three
types of AD facilities in the U.S.: stand-alone AD facilities; on-farm co-digestion facilities; and digesters at
WRRFs that co-digest food waste. Therefore, EPA used the EREF facilities list to help develop the list of
operating AD facilities that accept food waste, found in Appendix A of this document.
This report does not address whether the food waste processed at AD facilities could have been
prevented, donated to feed people, or used to feed animals. This report quantifies the capacity for
processing food waste, the amount of food waste processed at AD facilities, and additional relevant
information for calendar year 2015. By the time food that may at one time have been recoverable is
received by an AD facility, it is considered "food waste." Therefore, the term "food waste" is used
3	Advancing Sustainable Materials Management 2014 Fact Sheet, Table 1, page 8. Estimate includes residential,
commercial, and institutional sources of food waste, but not industrial or on-farm sources.
4	For the purposes of this report, food-based materials include but are not limited to food scraps that have been
separated and collected by municipalities from residential sources; food scraps that have been separated and
collected from institutions or venues (e.g., prisons, hospitals, stadiums); food scraps from food preparation at
restaurants, cafeterias, and other food services; plate scrapings from restaurants, cafeterias, and other food
services; fats, oils and grease (FOG); unused food collected from grocery stores (e.g., bakery items, bruised fruit,
items past shelf life); and pre-consumer by-products of the food and beverage processing industries.
5	AgSTAR is an EPA program that promotes the use of biogas recovery systems to reduce methane emissions from
livestock waste. For more information see: https:://www.epa.gov/agstar.
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throughout this document to describe the food waste or food-based feedstock being processed in
digesters.
II.	Survey Data Collection
Under ICR (No. 2533.01), EPA developed electronic data collection surveys for each digester type: stand-
alone food waste digesters, on-farm digesters that co-digest food waste, and digesters at WRRFs that
co-digest food waste. EPA emailed the surveys directly to digester operators and made the surveys
available on EPA's Anaerobic Digestion website. EPA collected data from January 2017 through
December 2017.
This data collection, which focused on the year 2015, allowed EPA to:
•	Identify the number and location of AD facilities processing food waste;
•	Document the total processing capacity at these AD facilities;
•	Document the types of food and non-food wastes, and the sources of these wastes, that are
accepted in AD facilities;
•	Document how much food waste was processed;
•	Document how much biogas was produced;
•	Analyze the end-uses of AD products (biogas and digestate); and,
•	Understand additional information about AD facilities such as pre-processing/de-packaging
activity, operational specifications, and gas cleaning systems.
Completion of the survey was voluntary and the data collected was voluntarily reported by survey
respondents. EPA identified the AD facilities included in this report using publicly available resources.
Information that survey respondents submitted that was not publicly available was not included in this
report. EPA aggregated the technical data collected for each facility (e.g., processing capacity) and
summarized it such that individual facility information could not be identified. Personally Identifiable
Information will be protected to the extent allowable under the Freedom of Information Act.
III.	Results
A. Location Data and Response Rates
EPA confirmed that 154 AD facilities processing food waste were operational. As described below,
another 30 facilities are believed to be operational, bringing the total operational (confirmed plus
unconfirmed) to 184. Surveys were returned by 137 of the 184 total operational facilities (Table 1).
EPA's research also identified facilities that have ceased operations, are in the planning, design and
construction phase, or did not advance beyond the pilot stage for a variety of reasons. A list of these
facilities is not included in this report.
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Table 1: Number of Anaerobic Digestion Facilities Identified, Operational, and Responding to Survey
	by Type (2015)	
Digester type
Operational
(Confirmed)
Operational
(Not Confirmed)
Operational
(Confirmed +
Non-Confirmed
Submitted
Survey
Survey
Response
Rate
Stand-alone
digesters
58
3
61
50
82%
On-farm digesters
18
25
43
15
35%
Co-digestion
systems at WRRFs
78
2
80
72
90%
Total
154
30
184
137
74%
Stand-Alone Digesters
Stand-alone digesters are primarily built to process food waste. While many of these digesters accept
other organic materials (e.g., manure, wastewater solids), they are typically designed to process food
waste. Stand-alone digesters are divided into two categories, as described below: multi-source food
waste digesters, and industry dedicated digesters.
Multi-Source Food Waste Digester: A digester that accepts and processes organic materials
(feedstocks), often obtained from multiple sources. These digesters are typically designed to
manage source-separated waste streams from a variety of sources including municipalities and
institutions. Other sources of feedstock may include processing waste from the food and
beverage industry, food waste from the food service or retail industries, or fats, oils, and grease
(FOG).
Industry-Dedicated Digester: A digester that is typically developed adjacent to a food-or
beverage- processing plant to process the waste from that plant. These digesters do not usually
accept organic materials from outside sources.
EPA received 50 survey responses from a field of 61 operational stand-alone facilities for a response rate
of 82%. The remaining 11 facilities did not submit data. EPA confirmed that eight of these 11 facilities
are operational. The last three are believed to be operational. See Appendix A, Table 1A, for a list of all
61 facilities.
According to the survey responses received from the 50 operating stand-alone digesters: 28 are multi-
source (56%); 20 are industry dedicated (40%); and two were identified by survey respondents as
"other" (4%).
Operational stand-alone digesters are located within 24 states. See Figure 1 for a map and Table 2 for a
list of operating stand-alone facilities (confirmed and non-confirmed) by state.
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Stand-Alone
Figure 1: Operating Stand-Alone Food Waste Digesting Facilities by State (2015)
On-Farm Digesters
According to EPA's AgSTAR program, there are approximately 250 anaerobic digester facilities operating
on livestock farms in the U.S. These digesters are primarily used for manure management. This survey
targeted only those digesters that are co-digesting food waste. EPA received 15 survey responses out of
the 43 operational on-farm digester facilities that are co-digesting food waste, for a response rate of
35%. The remaining 28 farms did not submit data. EPA confirmed that three of the 28 that did not
submit data are operational. Information on the other 25 farm digesters was found in BioCycle Magazine
articles, articles in other publications, American Biogas Council profiles, etc. As a result, these digesters
are believed to be operational. See Table 2A in Appendix A for a list of all 43 farms and Figure 2 for a
map of operating on-farm digesters (confirmed and non-confirmed) by state.
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On-Farm
Figure 2: Operating On-Farm Food Waste Co-Digestion Systems by State (2015)
Operational on-farm digesters co-digesting food waste were located within 14 states. At the time that
this data was collected, one of the six farm co-digestion systems in Vermont was in the planning, design
and construction phase.
Digesters at Water Resource Recovery Facilities (WRRFs)
The Water Environment Federation and the American Biogas Council built and maintain a database
(biogasdata.org) of information on WRRFs.6 This database identifies approximately 1,200 WRRFs in the
U.S. that have anaerobic digesters to manage wastewater solids, and roughly 20% of these facilities co-
digest materials, including food waste from offsite sources.
EPA received 72 survey responses from a field of 80 WRRFs with operational food-waste co-digestion
systems for a response rate of 90%. The remaining eight facilities did not submit data. EPA confirmed
that six of these eight facilities are operational. The last two are believed to be operational. See Table 3A
in Appendix A for a list of all 80 facilities and Figure 3 for a map of operating WRRF food waste co-
digestion systems (confirmed and non-confirmed) by state. WRRFs with operating co-digestion systems
are located within 25 states.
6 Please see http://www.resourcerecovervdata.org/blogasdata.php for a listing of those WRRFs with operating AD.
5

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WRRF
Figure 3: Operating WRRF Food Waste Co-Digestion Systems by State (2015)
Figure 4 and Table 2 summarize total operating digesters (confirmed and non-confirmed) by type and
location. Note that not all operating facilities provided survey responses.
Figure 4: Operating Food Waste Digesting Facilities by State (2015)

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Table 2: States with Operating Anaerobic Digestion Facilities (Confirmed and Non-Confirmed) by
	Facility Type (2015)	

Number of Facilities
State
Stand-Alone
On-Farm
WRRF
Alabama
0
0
1
Arizona
0
0
1
Arkansas
0
0
1
California
11
1
20
Colorado
0
0
1
Connecticut
1
0
0
Florida
2
0
3
Georgia
1
0
3
Idaho
1
1
0
Iowa
0
3
5
Illinois
0
0
3
Indiana
1
1
1
Kansas
0
0
2
Maine
2
1
1
Maryland
0
1
0
Massachusetts
5
3
1
Michigan
1
0
1
Minnesota
3
0
0
Missouri
1
0
0
Nebraska
0
0
1
New Hampshire
1
0
0
New Jersey
2
0
3
New York
4
5
6
North Carolina
1
0
0
North Dakota
2
0
0
Ohio
8
1
4
Oregon
2
0
3
Pennsylvania
2
8
4
South Carolina
0
0
1
Tennessee
1
0
0
Texas
1
0
2
Vermont
2
6
1
Virginia
0
0
2
Washington
1
6
0
Wisconsin
5
6
9
Total
61
43
80
B. Processing Capacity
Processing capacity refers to the maximum amount of food waste feedstock an anaerobic digester can
accept per unit time. In this survey, that unit of time was one year. EPA collected data on food waste
7

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processing capacity in either gallons or tons.7 Capacity reported in gallons was converted to tons to
quantify the total capacity available for processing food waste.8 EPA recognizes that most anaerobic
digesters typically process a liquid slurry. However, for food waste processing capacity, EPA converted
the data from gallons per year to tons per year because tons are the industry standard for measuring
food waste.
Based on a survey response rate of 95% for information about food waste processing capacity, EPA
documented that the total capacity for processing food waste in all three digester types combined is
15,809,647 tons per year (Table 3). Note that the actual processing capacity is likely to be higher than
the values reported in Table 3 because not all facilities known to be operating responded to the survey.
Stand-Alone Digesters
All 50 (100%) of the survey respondents provided data on processing capacity. The total current
processing capacity reported for food waste at stand-alone digesters in the U.S. is 12,563,687 tons per
year.
On-Farm Digesters
EPA asked operators of on-farm digesters to consider the following when calculating available food
waste processing capacity:
Taking into account the average volume of manure from your livestock processed in your
anaerobic digestion system, please identify the available capacity to co-digest other feedstocks.
EPA's goal was to determine how much outside food waste feedstock could potentially be processed at
on-farm digesters in the U.S. All 15 survey respondents provided data on processing capacity, which
totals 210,754 tons per year. This number only represents 35% of the on-farm co-digestion systems
potentially operating in the U.S. Therefore, the actual capacity is likely to be greater than this amount.
Co-Digestion Facilities at WRRFs
Determining the capacity for WRRFs to co-digest food waste is more challenging because there are more
factors to consider than just the size of the tanks. EPA asked plant operators to consider the following
when calculating available food waste processing capacity:
Please identify your facility's available capacity to accept feedstocks from offsite sources for all
digesters combined. When calculating this available capacity, please take into account the
average volume of wastewater solids processed at your facility and the total capacity of your
digesters. Assume that your facility has all the necessary equipment to receive additional
feedstocks (e.g. a receiving station, storage, mixing equipment, etc.)
Again, EPA's goal was to determine how much outside food waste feedstock could potentially be
processed at WRRFs in the U.S. The data in this report directly reflects the information provided by the
7	Throughout this document "ton" refers to a US ton, which equals 2,000 lb.
8	The gallons to tons conversion for food waste was calculated based on a factor of 3.8 lbs/gallon. This factor
comes from VMuwertf>WeightSonyersjon_Fa^ors, USEPA ORCR, April 2016).
8

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plant operators that responded to the survey. For operating WRRF co-digestion systems, 90% of
respondents (65 out of 72) provided data on processing capacity. The total current processing capacity
reported for food waste at co-digestion systems at WRRFs in the U.S. in 2015 was 3,035,206 tons per
year.
Table 3: Total Capacity for Processing Food Waste via Anaerobic Digestion by Digester Type (2015)
Digester Type
Reported Capacity
(tons per year)
Mean
(tons per year)
Median*
(tons per year)
Respondents
Providing Data
Total Surveys
Received
Stand-alone
12,563,687
251,274
45,000
50
50
digesters





On-farm
210,754
14,050
7,600
15
15
digesters





Co-digestion
3,035,206
42,156
9,595
65
72
systems at





WRRFs





Total
15,809,647


130
137
* Amounts were reported by facility response
C. Operational Dates
The general perception is that processing food waste via anaerobic digestion is a relatively new practice.
Most of the facilities that provided data for this survey began operations well before 2015 (Figure 5). For
co-digestion at WRRFs, the earliest start date reported was over 50 years ago (1966), and stand-alone
digesters were not that far behind (1969). Twenty stand-alone and WRRF digesters began processing
food waste in the 1980s and 1990s. In the early 2000s, AD of food waste and co-digestion of food waste
with other waste streams started to become more prevalent in the U.S. The practice took a little longer
to reach the farming sector. According to the survey responses received from farmers, co-digestion at
on-farm digesters did not begin until 2005.
20
15
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D. Food Waste Processed
EPA requested data on the amount of food waste processed via AD, reported in either gallons or tons.
Capacity reported in gallons was converted to tons.9 As with information about capacity, the amount of
material processed is reported in tons because tons are the industry standard for measuring food waste.
Note that the actual amount of food waste processed in 2015 was likely to be higher than the value
reported in Table 4 because not all facilities known to be operating provided data. Projecting or
predicting volumes processed at non-reporting facilities was not within the scope of this report.
Table 4: Total Amount of Food Waste Processed by Each Digester Type (2015)
Digester Type
Reported Amount
Processed (tons)
Mean
(tons per year)
Median*
(tons per year)
Respondents
Providing Data
Total Surveys
Received
Stand-alone
9,828,081
189,002
13,361
41
50
digesters





On-farm
112,879
6,640
790
14
15
digesters





Co-digestion
2,789,697
37,699
3,126
58
72
systems at





WRRFs





Total
12,730,657


113
137
* Amounts were reported by facility response
E. Non-Food Waste Processed
EPA also collected data on the amount of non-food waste processed via AD, in either gallons or tons.
Non-food waste feedstocks include, but are not limited to: mixed yard waste, crop residues, manure,
wastewater solids (sludge), septage, de-icing fluid, lab (or pharma) wastes, paper mill wastes, and crude
glycerin. Given that the content of non-food waste feedstocks is highly variable and can be liquid or
solid, there is no suitable conversation factor to combine values reported in different units. Therefore,
both liquid volume and solid weight amounts reported by facility operators are presented in Table 5.
The scope of this project is limited to include only the non-food waste feedstocks at anaerobic digesters
that digest food waste. It does not include documentation of non-food waste at facilities that do not
process any food waste. For example, this project does not include the large amount of manure being
digested at farm digesters that do not co-digest food, or the large amount of wastewater solids being
digested in digesters at WRRFs that do not co-digest food. Therefore, the numbers below represent only
a portion of non-food waste being digested in the U.S. The non-food waste data collected was intended
to provide additional information about the types of wastes being processed via AD.
9 The gallons to ton conversion for food waste was calculated using 3.8 lbs/gallon (See Volume-to-Weight
Conversion Factors, USEPA ORCR, April 2016).
10
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Table 5: Total Amount of Non-food Waste Processed by each Digester Type (2015)
Digester Type
Amount
(liquid)
Amount
(solid)*
Respondents
Providing Data
Total Surveys
Received
Stand-alone digesters
34,341,130 gallons
134,757 tons
23
50
On-farm digesters
2,940,000 gallons
2,103 tons
5
15
Co-digestion systems at WRRFs
2,182,707,046 gallons
324,863 tons
32
72
Total
2,219,988,176 gallons
461,723 tons
60
137
* Amounts were reported in liquid and solid units. Because there is no common conversion factor for non-food waste, these
values are separated.
As mentioned previously, not all operational digesters provided data for this project. The actual amount
of non-food waste processed at anaerobic digesters that digest food waste in 2015 is likely to be higher
than the value reported above.
F. Feedstock Types
A wide variety of feedstocks are processed in digesters throughout the U.S. Some feedstocks are more
common than others, which varies based on local availability, demand, and type of digester accepting
the feedstock. Tables 6, 7 and 8 and Figure 6 show the types of food waste and non-food waste
feedstocks processed at each of the three types of digesters. Figure 6 shows the top five feedstocks
accepted by digester type. EPA did not collect data on the quantity of individual feedstocks processed.
Feedstocks are classified as follows:
•	Food: beverage processing industry waste; food processing industry waste; FOG;
fruit/vegetative wastes; food service waste pre- & post-consumer; retail food waste; rendering
wastes; and source-separated commercial, institutional or residential organic wastes.
•	Non-Food: crude glycerin; manure; wastewater solids (sludge); septage; crop residues; mixed
yard waste; de-icing fluid; lab (or Pharma) wastes; and paper mill wastes.
Respondents from 48 of the 50 stand-alone facilities, all 15 on-farm digesters, and all 72 WRRFs
provided data on the type of feedstocks processed in 2015. Figure 6 indicates a summary of the top five
food waste and non-food waste feedstocks for all digester types. The top five are: FOG, food processing
industry waste, beverage processing industry waste, fruit/vegetable wastes, and pre-and-post-
consumerfood services waste.
11
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Table 6: Types of Food Waste and Non-Food Waste Feedstocks Processed at Stand-Alone Digesters (2015)

Number of Stand-Alone
Percentage of Stand-Alone
Feedstock
Facilities processing
Facilities processing this

this feedstock
feedstock*
Beverage processing industry waste
38
79%
Food processing industry waste
30
63%
FOG
27
56%
Fruit/vegetative wastes
25
52%
Food service waste, pre- & post-consumer
22
46%
Retail food waste
17
35%
Source-separated commercial, institutional or
17
35%
residential organic wastes


Crude glycerin
16
33%
Manure
16
33%
Wastewater solids (sludge)
11
23%
Rendering wastes
10
21%
Septage
6
13%
Other (please specify)*
6
13%
Crop residues
5
10%
Mixed yard waste
5
10%
De-icing fluid
2
4%
Lab (or Pharma) wastes
2
4%
Paper mill wastes
1
2%
* Percentage calculated based on the 48 facilities providing data on the type of feedstocks processed in 2015.
+ Other reported feedstocks include dairy processing wastes, landfill leachate, and poultry processing waste.
Table 7: Types of Food Waste and Non-food Waste Feedstock Processed at On-Farm Digesters (2015)

Number of On-Farm
Percentage of On-Farm
Feedstock
Facilities processing this
Facilities processing this

feedstock
feedstock*
Food processing industry waste
11
73%
FOG
10
67%
Beverage processing industry waste
7
47%
Fruit/vegetative wastes
6
40%
Food service waste, pre- & post-consumer
6
40%
Retail food waste
4
27%
Source-separated commercial, institutional or
3
20%
residential organic wastes


Crude glycerin
3
20%
Wastewater solids (sludge)
2
13%
Crop residues
1
7%
De-icing fluid
1
7%
Rendering waste
1
7%
* Percentage calculated based on 15 farms providing survey responses.
12
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Table 8: Types of Food Waste and Non-Food Waste Feedstock Processed at Co-Digestion Systems at
	WRRFs (2015)	
Feedstock
Number of WRRFs
Percentage of WRRFs
processing this feedstock
processing this feedstock*
FOG
62
86%
Food processing industry waste
36
50%
Septage
27
38%
Wastewater solids (sludge)
21
29%
Beverage processing industry waste
17
24%
Food service waste, pre- & post-consumer
16
22%
Fruit/vegetative wastes
13
18%
Crude glycerin
9
13%
Retail food waste
8
11%
De-icing fluid
7
10%
Rendering wastes
7
10%
Other (please specify)f
6
8%
Source-separated commercial, institutional or
5
7%
residential organic wastes


Lab (or Pharma) wastes
1
1%
Manure
1
1%
* Percentage calculated based on 72 WRRFs providing survey responses.

+ Other reported feedstocks include landfill leachate, poultry blood, non-toxic antifreeze, propylene glycol, and water
soluble industrial polymer waste.


100
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feedstock by digester type. Respondents from 48 of the 50 stand-alone facilities (96%), all 15 on-farm
digesters (100%), and 71 of 72 WRRFs (99%) provided data on sources of feedstocks processed in 2015.
Table 9: Sources of Food Waste and Non-Food Waste Feedstock Processed by Stand-Alone Digesters (2015)
Source
Number of Facilities Receiving
Feedstock from Specified Source
Percentage of Facilities
Receiving Feedstock from
Specified Source*
Food/beverage processors
36
75%
Restaurants and food service
23
48%
Grocery stores/supermarkets
22
46%
Biodiesel production
16
33%
Industrial
16
33%
Municipal/residential
15
31%
Schools
15
31%
Retail stores
13
27%
Livestock farms
12
25%
Sports and entertainment venues
12
25%
Wastewater treatment plants
12
25%
Corporate complex
10
21%
Hospitality
10
21%
Fruit/vegetable farms
7
15%
Prisons
6
13%
Airports
5
10%
Healthcare
5
10%
Laboratories/ pharmaceutical
companies
5
10%
Farmers markets
4
8%
* Percentage calculated is based on 48 facilities providing data on feedstock sources.
Table 10: Sources of Food Waste and Non-Food Waste Feedstock Processed by On-Farm Digesters (2015)
Source
Number of Facilities Receiving
Feedstock from Specified Source
Percentage* of On-farm
Digesters Receiving Feedstock
from Specified Source
Food/beverage processors
14
93%
Biodiesel production
5
33%
Grocery stores/supermarkets
5
33%
Restaurants and food service
4
27%
Hospitality
3
20%
Retail stores
3
20%
Corporate complex
2
13%
Healthcare
2
13%
Schools
2
13%
Airports
1
7%
Farmers markets
1
7%
Fruit/vegetable farms
1
7%
Industrial
1
7%
Prisons
1
7%
Wastewater treatment plants
1
7%
* Percentage calculated based on 15 farms providing survey responses.
14
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Table 11: Sources of Food Waste and Non-Food Waste Feedstock Processed by Co-Digestion Systems
	at WRRFs (2015)	
Source
Number of Facilities Receiving
Feedstock from Specified Source
Percentage of WRRFs
Receiving Feedstock
from Specified Source*
Restaurants and food service
52
73%
Food/beverage processors
43
61%
Municipal/residential
25
35%
Industrial
22
31%
Other wastewater treatment plants
22
31%
Grocery stores/supermarkets
18
25%
Schools
15
21%
Biodiesel production
10
14%
Retail stores
10
14%
Corporate complex
7
10%
Airports
6
8%
Healthcare
6
8%
Hospitality
6
8%
Prisons
6
8%
Sports and entertainment venues
6
8%
Fruit/vegetable farms
5
7%
Laboratories/pharmaceutical companies
3
4%
Farmers markets
2
3%
Livestock farms
1
1%
* Percentage based on 71 WRRFs providing data on feedstock sources.

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tipping fees to gain a better understanding of how digesters may be using them to offset capital
expenditures and maintenance costs. EPA recognizes that tipping fee data may be considered
proprietary and therefore made these questions optional as part of completing the survey.
Most survey respondents for all three digester types either did not answer the questions about tipping
fees, or indicated "$0.00" or "prefer not to say/' as the answer. Therefore, not enough information was
collected to draw meaningful or useful conclusions about tipping fee trends in 2015.
I. Pre-processing/De-packaging
EPA asked operators about the types of pre-processing and de-packaging performed at their facilities.
Respondents from 15 of the 50 stand-alone facilities, 6 of the 15 farm digesters, and 30 of the 72 WRRFs
provided data on pre-processing/de-packaging of feedstocks processed in 2015. Multiple types of pre-
processing or de-packaging can occur at any one facility. Tables 12, 13 and 14 show the number of
facilities that reported the use of each type of pre-processing/de-packaging activity in 2015.
Table 12: Pre-processing/De-packaging at Stand-Alone Digester Facilities (2015)
Pre-processing/De-packaging Activity
Number of Facilities with Specified Pre-
processing or De-packaging Activities
Manual or Mechanized De-packaging
10
Grinding and/or Maceration
6
Screening for Debris or Sorting
3
Third-Party Processing
2
Recyclable and Residue Removal System
1
Centrifugal Separation
1
Table 13: Pre-processing/De-packaging at On-Farm Digester Facilities (2015)
Pre-processing/De-packaging Activity
Number of Facilities with Specified Pre-
processing or De-packaging Activities
Manual or Mechanized De-packaging
3
Third-Party Processing
2
Grinding
1
Shredding
1
Table 14: Pre-processing/De-packaging at Co-Digestion Facilities at WRRFs (2015)
Pre-processing/De-packaging Activity
Number of Facilities with Specified Pre-
processing or De-packaging Activities
Screening for Debris or Sorting
14
Third Party Processing
11
Grinding and/or Maceration
8
Heating
5
Manual or Mechanized De-packaging
2
pH Adjustment
2
Pulping with a paddle finisher
1
Liquid/Solid Separation
1
16
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J. Operational Specifications
EPA asked respondents to share information about the operational specifications of their digesters,
including temperature range and whether operations were wet or dry. The temperature ranges are
typically 86 - 100° F for mesophilic and 122 - 140° F for thermophilic. Wet and dry classifications of
digesters refer to the moisture content of the feedstocks. A wet digester generally processes feedstock
with less than 15% solids content, whereas a dry digester generally processes feedstock with greater
than 15% solids content.
Respondents from 48 of 50 stand-alone facilities (96%), all 15 on-farm digesters, and all 72 WRRFs
provided data on temperature range. Respondents from all 50 stand-alone digesters and all 15 on-farm
digesters provided data on whether their digester system was wet or dry. This question was not posed
to WRRFs because all WRRF digester systems are wet. Tables 15 and 16 show the data for temperature
range and wet versus dry facilities by facility type.
Table 15: Temperature Range Data for each Digester Type (2015)

Temperature Range
Response Rate
Digester
Type
Mesophilic
Thermophilic
Unheated
Number of Respondents
Providing Data for this
Survey Question
Total Surveys
Received
Stand-alone
30
8
10
48
50
digesters





On-farm
12
2
l
15
15
digesters





Co-digestion
66
5
l
72
72
systems at





WRRFs





Total
108
15
12
135
137
Table 16: Data on Wet vs. Dry Systems for each Digester Type (2015)

Wet vs. Dry Systems
Percentage
Response Rate
Digester
Type
Wet
Dry
Wet
Dry
Number of Respondents
Providing Data for this
Survey Question
Total Surveys
Received
Stand-alone
46
4
92%
8%
50
50
digesters






On-farm
15
0
100%
-
15
15
digesters






Co-digestion
-
-
100%
-
-
-
systems at






WRRFs*






Total
61
4


65
65
* This question was not posed to WRRFs because all WRRF digester systems are wet.
K. Biogas Production
Biogas production data was collected in, or converted to, standard cubic feet per minute (SCFM), which
is the industry standard unit of measurement for biogas. The total biogas produced is summarized
17
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below as reported by facility type. SCFM was then used to estimate installed capacity in megawatts
(MW), and generation potential in kilowatt-hours per year (kWh/yr) using methods described in the
interactive conversion tool10 on EPA's Landfill Methane Outreach Program (LMOP) website.11 The LMOP
interactive conversion tool assumes landfill gas is 50% methane. The calculation for SCFM landfill gas to
MW capacity was revised for the purposes of this report to reflect that biogas tends to be about 60%
methane. To provide a frame of reference, EPA presents the kWh/yr values for each type of digester in
terms of powering homes.12 Table 17 shows biogas production data by facility type.
	Table 17: Summary of Biogas Data Reported by Digester Type (2015)	
Digester Type
Respondents
Providing
Data
Surveys
Received
SCFM*
MW
kWh/yr
(million)
Number of
Homes
Powered for
One Year
Stand-alone digesters
43
50
9,176
29
216
17,781
On-farm digesters
12
15
1,979
6
45
3,704
Co-digestion systems at
WRRFs
67
72
347,587
1,083
8,064
663,812
Total
122
137
358,742
1,117
8,317
684,639
* SCFM values are reported by facility operators and added together to get total SCFM for 2015 (358,742). The MW,
kWh/yr, and homes powered numbers are calculated using the LMOP interactive conversion tool. These values are
rounded to the nearest whole number, which accounts for the fact that the column totals may not sum.
L. Biogas Uses
Most facilities have more than one use for the biogas, and the survey permitted multiple responses.
Respondents from 49 of 50 stand-alone facilities (98%), all 15 on-farm digesters, and all 72 WRRFs
provided data on biogas uses. Table 18 summarizes the ways in which respondents reported using the
biogas produced and Figure 8 shows the top five uses of the biogas produced at AD facilities as reported
by each type of respondent.
Stand-Alone Digesters
The stand-alone digester survey asked respondents if the biogas produced was used onsite, sold, or
both. The data reported show that in 2015, 62% used the biogas onsite, 10% sold it, and 26% used it
both onsite and sold it. The survey also asked respondents if they were able to utilize all the biogas
produced at their facility. Eighty-two percent (82%) reported that all the biogas produced was used.
Sixteen percent (16%) reported that they did not use all the biogas produced. Facilities that did not use
all the biogas produced uniformly reported that they flared the unused biogas.
10	https://www.epa.gov/sites/production/files/2016-05/interactiveconversiontool.xls
11	Anaerobic Digestion and its Applications, EPA, October 2015, page 9.
12	The average home consumed 12,148 kWh of delivered electricity in 2016, the most recent date for which data is
available (https://www.epa.gov/energy/greenhouse-gases-equivalencies-calculator-calculations-and-references).
18
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On-Farm Digesters
The survey asked on-farm digester respondents if the biogas produced was used onsite, sold, or flared.
The reported data show that in 2015, 80% used the biogas onsite, 27% sold it, and 60% flared at least
some of the biogas.
Co-Digestion Systems at WRRFs
The WRRF co-digester survey asked respondents if the biogas produced was used onsite, sold, or flared.
The reported data show that 94% used the biogas onsite, 8% sold it, and 63% flared at least some of the
biogas. Two WRRFs out of 72 flared all the biogas they produced. The survey also asked WRRF
respondents if they utilized all the biogas produced at their facility. All 72 WRRFs provided data for this
question. Exactly 50% of the facilities reported that they used all the biogas produced for onsite
purposes. The other 50% confirmed that they flared the unused biogas.
WRRF operators also reported the following other uses, stated verbatim from the survey:
•	Jacket water from generators heats the anaerobic liquid through a heat exchanger;
•	Used exclusively by sludge pelletizing process;
•	Fuel steam boiler to produce steam for Class A dryer operation;
•	Absorption chiller, desiccant dehumidifier;
•	Fuel for thermal drying; and
•	Fuel for an off-site boiler.
19
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Table 18: Uses of Biogas Produced at Anaerobic Digesters (2015)

Stand-Alone Digesters
On-Farm Digesters
Co-Digestion Systems at
WRRFs
Biogas Use
Number of
Facilities
Reporting
Use
Percentage
of Facilities
using Biogas
as Specified*
Number of
Facilities
Reporting
Use
Percentage
of Facilities
using Biogas
as Specified*
Number of
Facilities
Reporting
Use
Percentage
of Facilities
using Biogas
as Specified§
Produce heat and
electricity (CHP)
32
65%
13
87%
51
71%
Fuel boilers and
furnaces to heat
digesters
9
18%
2
13%
44
61%
Fuel boilers and
furnaces to heat other
spaces
16
33%
1
7%
23
32%
Produce electricity
(sold to grid)
20
41%
10
67%
9
13%
Produce electricity
used behind the meter
(including net
metering)
14
29%
8
53%
16
22%
Produce mechanical
power
2
4%
2
13%
4
6%
Compressed to vehicle
fuels: used for
company
fleet/personal vehicles
4
8%
0
--
0
--
Compressed to vehicle
fuels: sold to customers
3
6%
0
--
1
1%
Renewable natural gas
(processed in order to
inject to pipeline)
2
4%
0
--
2
3%
*: Percentage out of the 49 facilities providing data on biogas uses.
+: Percentage out of the 15 farms providing survey responses.
§: Percentage out of the 72 WRRFs providing survey responses.
20
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mn
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Stand-Alone Digesters
On-Farm Digesters
Co-Digestion Systems at
WRRFs

Number of
Percentage
Number of
Percentage
Number of
Percentage
Constituent
Facilities
Reporting
Facilities
Reporting
Facilities
Reporting
Reporting
Removal of this
Reporting
Removal of this
Reporting
Removal of this

Removal
Constituent*
Removal
Constituent
Removal
Constituent
Oxygen &
1
3%
0
-
0
-
nitrogen






VOCs
1
3%
0
-
0
-
*: Percentage calculated based on 38 stand-alone digesters providing data on constituents removed via gas cleaning
systems.






+: Percentage calculated based on 11 farms providing data on constituents removed via gas cleaning systems.
§: Percentage calculated based on 47 WRRFs providing data on constituents removed via gas cleaning systems.
100

Sulfur	Moisture	Siloxanes Carbon Dioxide Hydrogen Sulfide
¦ Stand-Alone Digesters ¦ On-Farm Digesters ¦ WRRF Digesters
Figure 9: Top Five Constituents Removed by Digester Type (2015)
N. Solid Digestate Uses
EPA asked how facilities reused the solid digestate they produce, allowing respondents to provide more
than one answer. Respondents from 46 of 50 stand-alone facilities (92%), all 15 farm digesters, and all
72 WRRF digesters provided data on the uses of solid digestate. In 2015, 14 WRRFs landfilled all the solid
digestate they produced. The following uses/destinations of solid digestate were reported for the three
digester types surveyed at the frequencies specified in Table 20 below. Figure 10 shows the top five uses
of solid digestate by digester type.
Stand-alone digester operators also reported the following other uses, stated verbatim:
•	Solid onion remains are sold as cattle feed;
•	Dispersion in settling ponds; and
•	Land application of liquid digestate.
WRRF digester operators also reported the following other uses, stated verbatim:
22
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•	Third-party hauling and composting;
•	Used as backfill material in exhausted gypsum mines; and
•	Converted to fertilizer.
Out of the responses received from WRRF digester operators, 69 facilities out of 72 (96%) indicated that
they produce a Class A or Class B biosolid.13 Twenty percent of the responding facilities produced Class A
biosolids, and 80% produced Class B biosolids, in 2015.
Table 20: Solid Digestate Uses (2015)

Stand-Alone Digesters
On-Farm Digesters
Co-Digestion Systems at
WRRFs
Digestate Use
Number of
Facilities
Reporting
Use
Percentage
using Solid
Digestate
as Specified*
Number of
Facilities
Reporting
Use
Percentage
using Solid
Digestate as
Specifiedf
Number of
Facilities
Reporting
Use
Percentage
using Solid
Digestate as
Specified§
De-watered/
dried and land
applied
10
22%
7
47%
38
53%
Composted into
a reusable/
salable product
17
37%
2
13%
9
13%
Landfilled
6
13%
1
7%
18
24%
Other
16
35%
0
-
8
11%
Processed into
animal bedding
2
4%
12
80%
0
-
Dried into a
reusable/
salable product
(e.g., fertilizer)
0
-
0
-
8
11%
Land applied as
is with no
dewatering or
drying
0
-
0
-
7
10%
Incinerated
0
-
0
-
1
1%
* Percentage calculation based on 46 stand-alone facilities providing data on use of solid digestate.
+ Percentage calculation based on 15 farms providing survey responses.
§ Percentage calculation based on 72 WRRFs providing survey responses.
13 For additional information on biosolids, please see: https://www.epa.gov/biosolids
23
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60
50
40
30
20
10
De-watered/dried Composted into a
and land applied reusable/salable
product
¦ Stand-Alone Digesters
Landfilled
I On-Farm Digesters
Other
Processed into
animal bedding
WRRF Digesters
Figure 10: Top Five Uses of Solid Digestate by Digester Type (2015)
O. Liquid Digestate Uses
EPA asked how facilities manage liquid digestate, allowing respondents to provide more than one
answer. Respondents from 48 of 50 stand-alone facilities (96%), all 15 on-farm digesters, and all 72
WRRFs provided data on the management of liquid digestate, as summarized in Table 21.
Of the 20 stand-alone digesters that reused digestate as fertilizer via land application in 2015, only two
facilities further processed it prior to application (10%). Of the 14 on-farm digester operators that land
applied liquid digestate, only one on-farm digester operator indicated that the liquid was further
processed prior to application (7%). Six WRRF digesters indicated that the liquid digestate they produced
was land applied, and none of these facilities further processed it prior to application.
Table 21: Liquid Digestate Uses (2015)

Stand-Alone Digesters
On-Farm Digesters
Co-Digestion Systems at
WRRFs
Digestate Use
Number of
Facilities
Reporting
Use
Percentage
using Liquid
Digestate
as Specified*
Number of
Facilities
Reporting
Use
Percentage of
using Liquid
Digestate as
Specifiedf
Number of
Facilities
Reporting
Use
Percentage of
using Liquid
Digestate as
Specified§
Recirculated
through digester
10
21%
6
40%
62
86%
Reused as
fertilizer via land
application
20
42%
14
93%
6
8%
Discharged to a
wastewater
treatment plant
24
50%
0
-
0
-
Other
4
8%
0
-
8
11%
* Percentage calculation based on 48 stand-alone facilities providing data on use of liquid digestate.
+ Percentage calculation based on 15 farms providing survey responses.
§ Percentage calculation based on 72 WRRFs providing survey responses.
24
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Table 22: Data Collection Results for 2015
Area of Data Collection
Result
Total Processing Capacity
15,809,647 tons per year
Total Food Waste Processed
12,730,657 tons
Total Non-Food Waste Processed at Co-
2,219,988,176 gallons and 461,723 tons
Digesting Facilities

Total Biogas Produced
358,742 SCFM
Top-Three States with the Most Digesters
California, Wisconsin, New York
Top-Three Feedstock Types
FOG; Food Processing Industry Waste; Beverage
Processing Industry Waste
Top-Three Feedstock Sources
Food/beverage Processors; Restaurants & Food Services;
Grocery Stores/Supermarkets
Top-Three Biogas Uses
Produce Heat and Electricity (CHP); Fuel Boilers and
Furnaces to Heat Digesters; Fuel Boilers and Furnaces to
Heat Other Spaces
Top-Three Constituents Removed
Sulfur; Moisture; Siloxanes
Top-Three Uses of Solid Digestate
De-watered/dried and Land Applied; Composted into a
Reusable/Salable Product; Landfilled
Top-Three Uses of Liquid Digestate
Recirculated Through Digester; Reused as Fertilizer via
Land Application; Discharged to a Wastewater Treatment
Plant
EPA will continue to gather data and seek to verify data received in 2017 to clarify this information over
time. EPA will collect additional data for years 2016, 2017, and 2018 and will publish new reports in
2019 and 2020.
26
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Appendix A - Operational Digesters and Co-Digestion Systems
This appendix lists the facilities for each digester type surveyed regarding use of food waste and food-
based materials as a feedstock. The locations were identified using publicly available information. This
list is current as of December 2017. The tables are as follows:
Table 1A: Stand-Alone Anaerobic Digestion Facilities Digesting Food Waste in the U.S.
Table 2A: Farm Digesters Co-Digesting Food Waste in the U.S.
Table 3A: WRRF Digesters Co-Digesting Food Waste in the U.S.
Table 1A: Stand-Alone Anaerobic Digestion Facilities Digesting Food Waste in the U.S.


Multi-Source
Stand-Alone Facility Name
Location
(MS)/lndustry-
Dedicated
(ID)/Other*
Operational Facilities (Confirmed)
Ralphs Renewable Energy Facility
Compton, CA
ID
Fairfield Brewery BTS
Fairfield, CA
ID
MillerCoors Brewery
Irwindale, CA
ID
Monterey Regional Waste Management District
Marina, CA
MS
North State Rendering
Oroville, CA
MS
Gills Onions
Oxnard, CA
ID
CR&R Material Recovery Facility
Perris, CA
MS
Sacramento BioDigester
Sacramento, CA
MS
ZWEDC
San Jose, CA
MS
Blue Line Biogenic CNG Facility
South San Francisco, CA
MS
LA BTS
Van Nuys, CA
ID
Quantum Biopower
Southington, CT
MS
Jacksonville BTS
Jacksonville, FL
ID
Harvest Power Orlando
Lake Buena Vista, FL
MS
Cartersville BTS
Cartersville, GA
ID
J.R. Simplot Potato Processing Plant
Caldwell, ID
ID
Waste No Energy, LLC
Monticello, IN
MS
Stop & Shop Freetown Distribution Center
Assonet, MA
OTHER
Garelick Farms
Franklin, MA
ID
Garelick Farms
Lynn, MA
ID
Ken's Foods Inc
Marlborough, MA
ID
CRMC Bioenergy Facility
New Bedford, MA
MS
Exeter Agri-Energy
Exeter, ME
MS
Michigan State Univ. - South Campus Anaerobic Digester
Lansing, Ml
MS
American Crystal Sugar
East Grand Forks, MN
ID
Hometown BioEnergy
Le Sueur, MN
MS
American Crystal Sugar
Moorhead, MN
ID
St. Louis BTS
St. Louis, MO,
ID
Full Circle Recycle (Barham Farms)f
Zebulon, NC
MS
J.R. Simplot Potato Processing Plant
Grand Forks, ND
ID
American Crystal Sugar
Hillsboro, ND
ID
Merrimack BTS
Merrimack, NH
ID
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Multi-Source
Stand-Alone Facility Name
Location
(MS)/lndustry-
Dedicated
(ID)/Other*
Operational Facilities (Confirmed)
Newark BTS
Newark, NJ
ID
Lassonde Pappas
Seabrook, NJ
ID
CH4 Generate Cayuga LLC.
Auburn, NY
MS
AB-lnbev Baldwinsville
Baldwinsville, NY
ID
Buffalo BioEnergy
West Seneca, NY
MS
Niagara BioEnergy
Wheatfield, NY
MS
Emerald BioEnergy
Cardington, OH
MS
Central Ohio BioEnergy
Columbus, OH
MS
Columbus BTS
Columbus, OH
ID
Dovetail Energy
Fairborn, OH
MS
Haviland Energy
Haviland, OH
MS
Quasar
Independence, OH
MS
Buckeye Biogas LLC
Wooster, OH
MS
Zanesville Energy
Zanesville, OH
MS
Stahlbush Island Farms
Corvallis, OR
MS
D.G. Yuengling and Son, Inc.
Pottsville, PA
ID
Kline's Services
Salunga, PA
MS
Houston BTS
Houston, TX
ID
Vermont Tech Community AD
Randolph, VT
MS
Purpose Energy Digester at Magic Hat Brewery
South Burlington, VT
OTHER
J.R. Simplot Potato Processing Plant
Moses Lake, WA
ID
Bush Brothers & Company
Augusta, Wl
ID
Montchevre - Betin
Belmont, Wl
ID
Forest County Potawatomi Community Digester
Milwaukee, Wl
MS
UW-Oshkosh Urban Dry Digester
Oshkosh, Wl
MS
Greenwhey Energy
Turtle Lake, Wl
MS
Operational Facilities (Not Confirmed)§
Village Green Brunswick Landing
Brunswick, ME
MS
JC-Biomethane Biogas Plant
Junction City, OR
MS
Bush Brothers & Co.
Danridge, TN
ID
* "Other" reflects an industry dedicated digester that accepts outside feedstocks periodically, and a facility that
processes feedstocks from several of their own internal retail supermarkets.

+ Full Circle Recycle (Barham Farms) in Zebulon, NC was initially designated as a farm digester and is confirmed to be
operating. A stand-alone digester survey will be distributed during the 2018 data collection.

§These facilities are included in the operating count because they are believed to be operational (not confirmed).
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Table 2A: On-Farm Digesters Co-Digesting Food Waste in the U.S.
Farm Name
Location
Operational Co-Digestion Systems (Confirmed)
Link Energy
Riceville, IA
AgriReNew (Sievers Family Farms)
Stockton, IA
Bar-Way Farm
Deerfield, MA
Pine Island Farm
Sheffield, MA
Kilby's Inc
Colora, MD
Exeter Agri-Energy/Stonyvale Farm
Exeter, ME
Patterson Farms Inc.
Auburn, NY
Noblehurst Green Energy
Pavilion, NY
CH4/Synergy Biogas
Wyoming, NY
Mill Creek Dairy
West Unity, OH
Kish-view farm
Belleville, PA
Schrack farms
Loganton, PA
Reinford Farms Inc
Mifflintown, PA
Green Mtn Dairy
Sheldon, VT
Monument Farms Three-Gen
Weybridge, VT
Clean Fuel Dane, LLC
Dane, Wl
Five Star Dairy LLC
Elk Mound, Wl
Allen Farms Digester
Oshkosh, Wl
Operational Co-Digestion Systems (Not Confirmed
)*
Pixley Biogas (Four J Farms)
Pixley, CA
Amana Farms
Amana, IA
Big Sky West Dairy
Gooding, ID
Green Cow Power
Goshen, IN
Barstow's Longview Farm
Hadley, MA
Lamb Farms, Inc
Oakfield, NY
Lawn hurst Farm
Stanley, NY
Sensenig Dairy
Kirkwood, PA
Brubaker Farms
Mount Joy, PA
Benner's Yippee Farms
Mount Joy, PA
Kreider Farms
Quarryville, PA
Keefer Hard Earned Acres, Inc
Shippensburg, PA
Blue Spruce Farm
Bridport, VT
Maxwell Farm
Coventry, VT
Maplehurst Farm
Greenboro, VT
Chaput Family Farms
North Troy, VT
Van Dyk Holsteins
Everson, WA
Vander Haak Dairy/FPE Renewables
Lynden, WA
Qualco Energy
Monroe, WA
Farm Power Lynden (Enumclaw)
Mount Vernon, WA
Farm Power Rexville
Mount Vernon, WA
George Deruyter and Sons Dairy
Outlook, WA
Holsum Dairy (Irish Road)
Hilbert, Wl
Holsum Dairy (Elm Road)
Hilbert, Wl
Wild Rose Dairy
LaFarge, Wl
*These on-farm co-digestion systems are included in the operating count because they are believed to be
operational (not confirmed).
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Table 3A: WRRF Digesters Co-Digesting Food Waste in the U.S.
WRRF Name
Location
Operational Co-Digestion Systems (Confirmed)
Huntsville Spring Branch WWTP
Huntsville, AL
Fourche Creek Water Reclamation Facility
Little Rock, AR
Wildcat Hill Wastewater Treatment Plant
Flagstaff, AZ
Delta Diablo WWTP
Antioch, CA
Bakersfield Wastewater Treatment Plant # 2
Bakersfield, CA
Bakersfield Wastewater Treatment Plant # 3
Bakersfield, CA
Hill Canyon Wastewater Treatment Plant
Camarillo, CA
Encina Wastewater Authority WPCF
Carlsbad, CA
Joint Water Pollution Control Plant
Carson, CA
Sacramento Regional Wastewater Treatment Plant
Elk Grove, CA
Fairfield-Suisun Sewer District
Fairfield, CA
Fresno-Clovis RWRF
Fresno, CA
City of Hayward Water Pollution Control Facility
Hayward, CA
NapaSan Resource Recovery Facility
Napa, CA
East Bay Municipal Utility District Main Wastewater Treatment Plant
Oakland, CA
Silicon Valley Clean Water
Redwood City, CA
Oro Loma Sanitary District
San Lorenzo, CA
Central Marin Sanitation Agency
San Rafael, CA
El Estero WWTP
Santa Barbara, CA
Santa Rosa Regional Water Reuse Plant
Santa Rosa, CA
Victor Valley Wastewater Reclamation Authority
Victorville, CA
City of Watsonville
Watsonville, CA
City of Durango WWTP
Durango, CO
North Regional WWTP
Pampano Beach, FL
South Cross Bayou AWWTF
St. Petersburg, FL
Thomas P Smith WRF
Tallahassee, FL
F. Wayne Hill Water Resources Center
Buford, GA
South Columbus Water Treatment Facility
Columbus, GA
Lower Poplar Street WRF
Macon, GA
Ames WPC Plant
Ames, IA
Davenport WPC
Davenport, IA
Des Moines Metropolitan Wastewater Reclamation Authority
Des Moines, IA
Dubuque Water & Resource Recovery Center
Dubuque, IA
City of Waterloo, IA Anaerobic Lagoon
Waterloo, IA
Downers Grove Sanitary District
Downers Grove, IL
Rock River Water Reclamation District
Rockford, IL
Urbana & Champaign Sanitary District
Urbana, IL
West Lafayette WWRF
West Lafayette, IN
DLS Middle Basin
Overland Park, KS
Greater Lawrence Sanitary District
North Andover, MA
Lewiston-Auburn Water Pollution Control Authority
Lewiston, ME
Delhi Charter Township WWTP
Holt, Ml
Theresa Street WRRF
Lincoln, NE
Joint Meeting of Essex & Union Counties
Elizabeth, NJ
Village of Ridgewood WPCF
Glen Rock, NJ
Landis Sewerage Authority
Vineland, NJ
Newtown Creek Wastewater Treatment Plant
Brooklyn, NY
A-4
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WRRF Name
Location
LeRoy R. Summerson WWTF
Cortland, NY
Gloversville Johnstown Joint WTF
Johnstown, NY
Rome Water Pollution Control Facility
Rome, NY
Metropolitan Syracuse WWTP
Syracuse, NY
City ofWatertown Pollution Control Plant
Watertown, NY
City of London
London, OH
City of Newark WWTP
Newark, OH
Struthers waste water
Struthers, OH
Wooster WWTP
Wooster, OH
Gresham WWTP
Gresham, OR
City of Pendleton, WWTRRF
Pendleton, OR
Clean Water Services - Durham AWTF
Tigard, OR
Hermitage Municipal Authority
Hermitage, PA
Derry Township Municipal Authority
Hershey, PA
Milton Regional Sewer Authority
Milton, PA
New Castle Sanitation Authority
New Castle, PA
Mauldin Road WRRF
Greenville, SC
Southside Wastewater Treatment Plant
Dallas, TX
Waco Metro - Area Regional Sewage System
Waco, TX
Village of Essex Junction
Essex Junction, VT
North River Wastewater Treatment Facility
Mt. Crawford, VA
Opequon Water Reclamation Facility
Winchester, VA
Appleton Wastewater Treatment Plant
Appleton, Wl
Fond du Lac Regional Wastewater Treatment & Resource Recovery

Facility
Fond du Lac, Wl
City of Kiel
Kiel, Wl
MMD South Shore Water Reclamation Facility
Oak Creek, Wl
City of Port Washington WWTP
Port Washington, Wl
City of Rice Lake
Rice Lake, Wl
Stevens Point WWTP
Stevens Point, Wl
City of West Bend Wastewater Treatment Plant
West Bend, Wl
Wisconsin Rapids WWTF
Wisconsin Rapids, Wl
Operational Co-digestion Systems (Not Confirmed)*
Eastern Municipal Water District
Moreno Valley, CA
Lawrence Wastewater Treatment Plant 118
Lawrence, KS
*These WRRF co-digestion systems are included in the operating count because they are believed to be
operational (not confirmed).

A-5
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Appendix B - Survey Questions
This appendix provides the lists of questions asked via a survey for each digester type regarding their use
of food waste and food-based materials as a feedstock. EPA distributed the surveys via email directly to
facility contacts, when known, and made the survey available on EPA's website. When the survey for the
2018 data collection is available, it will be posted.
Survey 1: Stand-Alone Anaerobic Digestion Facility Survey Questions
Survey 2: On-Farm Digester Survey Questions
Survey 3: Co-Digestion Systems at Water Resource Recovery Facilities Survey
Questions
B-l
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