Organics: Anaerobic Digestion

Why Focus on Food Scraps?

Food scraps account for 18% of waste currently reaching landfills in the United States.
Food scraps in landfills decompose to generate methane, a potent greenhouse gas.
Food scraps are a valuable resource with potential to create renewable energy and to be used as a valuable soil amendment.
Using food scraps as a resource rather than disposing of them in a landfill reflects cradle-to-cradle, closed loop approach.

For more information on food wasrte visit EPA's F- website.

Anaerobic digestion is a process where microorganisms break down organic materials, such as food scraps, manure, and sewage sludge, in the absence of oxygen. Anaerobic digestion produces biogas and a solid residual. Biogas, made primarily of methane and carbon dioxide, can be used as a source of energy similar to natural gas. The solid residual can be land applied or composted and used as a soil amendment. The benefits of anaerobic digestion include renewable energy generation, greenhouse gas emissions reduction, and waste diversion.

Anaerobic digestion occurs at:

Co-Digestion is a process whereby additional, energy-rich organic waste materials (e.g. Fats, Oils, and Grease (FOG) and/or food scraps) are added to a dairy or wastewater digester with excess capacity. Co-digestion uses existing infrastructure to divert food scraps and FOG. In addition to diverting food scraps and FOG from landfills and the public sewer lines, these high-energy materials have at least three times the methane production potential of biosolids and manure. Methane production potential correlates to the amount of energy that the material produces when digested anaerobically.

Permitting Tool Kit for Food Waste Anaerobic Digesters - Based on the experience of Humboldt Waste Management Authority (HWMA) in California, this report provides an overview of key permitting steps and regulatory requirements for anaerobic digesters processing wasted food. It includes:

Key Permitting Steps
Overview of the Current Regulatory Environment
List of Potential Impacts and Mitigations Measures
Lessons Learned Throughout the Permitting Process

While permitting and regulatory requirements differ by geographic location, site characteristics, and the size of the project, this provides general information about permitting and specific information about HWMA’s experience. The purpose is to help other cities and project developers move through the permitting process with more ease.

Co-Digestion Financial Analysis Tool – New tool to help assess initial economic feasibility assessment of food waste co-digestion at wastewater treatment plants for the purpose of biogas production.

Turning Food Scraps Into Energy- Learn more about how East Bay Municipal Utility District (EBMUD) is co-digesting food scraps from restaurants in the San Francisco Bay Area at their wastewater treatment plant to generate renewable energy.