Anaerobic Digestion

Anaerobic digestion (AD) is a process by which microorganisms break down organic matter, producing various gases and a reduced volume of semi-solid residue.  The gases produced, called "biogas" or "digester gas," include a high percentage of methane, which can be burned to produce heat and/or electricity.  Biogas from anaerobic digestion of biosolids and other organic residuals is a renewable, green fuel.  The semi-solid residue from the digestion process, called "digestate" (and/or "biosolids," if it is derived from wastewater solids and meets regulatory standards for use on land) is a stabilized material that can be used as a soil amendment, for animal bedding, or other uses, depending on the levels of further treatment.

Anaerobic digestion of organic residuals is a rapidly growing market, because it is a critical part of making communities sustainable.  In New England and eastern Canada, wastewater treatment facilities traditionally did not use AD.  Now there is booming interest in building more digesters.

See: 


Additional Resources

American Biogas Council (ABC)
AgStar Anaerobic Digestion Website
U. S. EPA Biosolids Program & Regulations
U. S. EPA - East Bay MUD Food Waste Digestion Info
Toronto Anaerobic Digestion System - "Going Green for Green" VIDEO
Disneyworld Food Scraps to Digestion - VIDEO (2014)


NEBRA Webinars & Workshops

Co- Composting & -Digestion of Organics - recording of a NERC/NEBRA webinar, Dec. 3, 2015 (1 hour, 17 mins.)  Discussion of co-composting & co-digestion by Jeff McBurnie (Casella Organics) and co-digestion by Natalie Sierra (Brown and Caldwell), with input by Mac Richardson, Lewiston-Auburn Water Pollution Control Association.


NEBRA / JETTC Anaerobic Digestion Workshop

Lewiston-Auburn WPCA, Maine • September 10, 2013

Georgine Grissop, CDM SMith:  Anaerobic Digesters 101: Process Description and Process Control
John Donovan, CDM Smith:  Basis of Design of LAWPCA Digestion / Energy Recovery Facilities
John Reilly, Hoyle Tanner & Associates:  Biogas
Dan Kelly, Tom Schwartz, Woodard and Curran:  NEWEA 2013 - Combined Heat and Power
Ned Beecher, NEBRA:  Co-Digestion: The Path to Net-Zero Energy Consumption
Travis Peaslee, LAWPCA:  Stakeholder Concerns 


Massachusetts Digester Day - May 2012

May 8, 2012.  The agenda for the day's presentations is here.
All presentations are courtesy of presenters; please contact them for permission to utilize for other than personal use.

Digester Basics - Paul Greene, American Biogas Council (ABC) / O'Brien & Gere
Biosolids Digestion - John Donovan, CDM Smith
Biosolids Regulations - Natalie Sierra, RMC Water and Environment
Digester Gas: Uses & Considerations - Michael Bullard, Hazen & Sawyer
CoDigestion of Biosolids - Natalie Sierra, RMC Water and Environment
Manure and Food Waste Digestion - Paul Greene, ABC / O'Brien & Gere
Stakeholder Concerns - Ned Beecher, NEBRA
Case Study: East Bay Municipal Utility District (EBMUD) - Natalie Sierra / Ned Beecher
Overcoming the Challenges / Discussion Slides - Wayne Davis, Harvest Power
Summary Comparison of MA DEP Biosolids Regulations v. U. S. EPA
Summary of Biosolids Recycling in MA

The egg-shaped anaerobic digester at the Nashua, NH Wastewater Treatment Facility.