Anaerobic digestion is a collection of processes by which microorganisms break down biodegradable material in the absence of oxygen. The process is used for industrial or domestic purposes to manage waste and/or to produce fuels. Typically, three things come out of an anaerobic digester for beneficial reuse: Biogas (which can be turned into electricity and heat, or fuel), Solid Fertilizer (from the digestate, the materials after they have been digested) and Liquid Fertilizer (from the centrate, the liquids after they have been digested).

Many types of organic material can be used as feedstock to produce biogas. Animal manures, wastewater solids, food scraps, restaurant fats, oils, and greases, and by-products from food and beverage production are some commonly digested materials. An anaerobic digester may be built for a single material or a combination of them. However, the feedstocks must be properly controlled to ensure that the system remains healthy and functioning.

Most municipalities are investing in ways to divert materials from landfills. This is usually due to reduced landfill space and/or recycling goals. Wastewater treatment facilities offer the opportunity to divert large amounts of food waste, one of the largest waste streams still going to landfills.

Food waste is one of the single largest constituent of municipal solid waste stream. In a typical landfill, food waste is one of the largest incoming waste streams and responsible for the generation of high amounts of methane. Diversion of food waste from landfills can provide significant contribution towards climate change mitigation, apart from generating revenues and creating employment opportunities.

Reducing the amount of food wasted has significant economic, social & environmental benefits:

Environmental Benefits

There are many resources needed to grow food, including water, fertilizers, pesticides, and energy. By wasting food, you are also wasting the resources that when into growing it. Additionally, 13 percent of greenhouse gases in the United States are associated with growing, manufacturing, transporting, and disposing of food. By reducing the amount of food wasted, we can reduce greenhouse gas emissions.

Economic Benefits

Lower disposal costs by decreasing the amount of food wasted, businesses pay less to dispose of their trash. By making strides to prevent food waste, businesses can reduce costs by purchasing only the food that will be used, or decreasing improperly prepared foods. Additionally, reducing food waste can increase staff efficiency and reduce energy and labor associated with disposing of food. Finally, by donating wholesome and edible food to food banks or food rescue organizations, businesses can claim tax benefits as well as feed those in need.

Social Benefits

An estimated 50 million Americans do not have access to enough food. Organizations can donate safe and healthy food to a food bank or food rescue organization and both reduce food sent to landfills and feed people in need.

When food is disposed in a landfill it rots and becomes a significant source of methane – a potent greenhouse gas with 21 times the global warming potential of carbon dioxide. Landfills are a major source of human related methane in the United States, accounting for more than 20 percent of all methane emissions.

A wide variety of businesses can contribute foodwaste to an anaerobic digestor including grocery stores, restaurants, commercial food processing entities and industrial food processing companies.