Compostable Materials

Anaerobic Digestion

Anaerobic digestion (AD) is the biological decomposition of organic matter with little or no oxygen. The anaerobic digestion process occurs naturally in marshes and wetlands. There are a variety of controlled systems where anaerobic technology is currently utilized in the United States, including wastewater treatment facilities (also Public-Operated Treatment Works or POTWs), and dairy manure digesters. In other countries (primarily Europe), anaerobic technology is utilized in municipal solid waste digesters to produce energy and to reduce the volume of solid waste that must be landfilled.

CalRecycle is encouraging the development of technologies that divert organic waste from landfills and comply with the Global Warming Solutions Act of 2006 (AB 32). AB 32 calls for the reduction of greenhouse gases and the use of low carbon fuels, and solid waste landfills are a significant source of greenhouse gases due to decomposition of organic material in landfills into methane. Anaerobic digestion is being considered for many projects to divert organic materials from landfills and produce low carbon fuels.

Current Initiatives

As interest in using anaerobic digestion to manage organic waste at various types of facilities grows, permitting questions are raised. To assist in the siting and permitting of these facilities in California, CalRecycle has several initiatives underway, including development of a Program Environmental Impact Report and guidance documents.

• Program Environmental Impact Report (EIR) for Anaerobic Digestion Facilities: This Program EIR assesses the environmental effects that may result from the development of anaerobic digestion facilities in California. The results of the Program EIR will inform future policy considerations related to anaerobic digestion facilities and provide background information on technologies, potential impacts, and mitigation measures. If you require assistance in obtaining access to these documents, call the Public Affairs Office at (916) 341-6300 or Ken Decio at (916) 341-6313.
  • Final Program EIR (PDF, 8.3 MB). The Final Program EIR was certified on June 22, 2011 after a June 21 public meeting to provide an update and overview of the EIR. Documents related to certification of the Final Program EIR include:
    • Guidance Document for CEQA Review of Municipal Organic Waste Anaerobic Digester Facilities in California (PDF, 372 KB)
    • Staff Recommendations (PDF, 136 KB) on CEQA Findings
    • Mitigation Monitoring and Reporting Plan (PDF, 85 KB),
    • Anaerobic Digestion Initiative (PDF, 44 KB)
    • Request for Certification of the Anaerobic Digestion Final Program EIR and Approve Anaerobic Digestion Initiative (PDF, 243 KB)
    • Notice of Determination (PDF, 261 KB)
    • Department of Fish and Game CEQA Filing Fee No Effect Determination (PDF, 270 KB)
  • Draft Program EIR (PDF, 2.3 MB) was available for public comment through April 4, 2011. Comments were also accepted at the CalRecycle Monthly Public Meeting on March 15, 2011 in Sacramento and at a special public meeting for southern California jurisdictions on March 30, 2011 in Lakewood.
  • Notice of Preparation (PDF, 138 KB), April 30, 2010.
• How Anaerobic Digestion Fits Current Board Regulatory Structure. This guidance document provides a detailed review of the way anaerobic digestion activities are to be regulated under the Integrated Waste Management Act.

Additional Guidance

• 2012 Bioenergy Action Plan

• Dairy Manure Digester And Co-Digester Facilities Draft Program Environmental Impact Report (PDF, 18.4 MB)
• Dairy Manure Digester And Co-Digester Facilities Final Program Environmental Impact Report (PDF, 8.7 MB)

• Permit Guidance for Anaerobic Digesters and Co-Digester Manual (California Environmental Protection Agency) (PDF, 1.32 MB)

• Anaerobic Digester Projects (California Environmental Protection Agency)

• Current Anaerobic Digestion Technologies Used for Treatment of Municipal Organic Solid Waste. (2007) Note: This document was written prior to the enactment of SB 1016 (Wiggins, Chapter 343, Statutes of 2008), which changed how jurisdiction diversion rates are calculated. As a result, portions of the discussion in this document about diversion calculations are out of date. They will be updated in the near future.
• New and Emerging Conversion Technologies: Report to the Legislature (442-05-016).
• Increasing Siting and Capacity of Organic Diversion Facilities.
• Safely Disposing of Waste Meat, Poultry, and Fish Material: Guidance and FAQs (PDF, 123 KB | Word, 64 KB).
• LEA Advisory 58, Methodology for Determining Compliance: In April 2003, CalRecycle issued this advisory to provide guidance to LEAs in implementing the three-part test.

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