Anaerobic Digestion

“Anaerobic digestion is a biological process that produces a gas principally composed of methane and carbon dioxide, otherwise known as biogas. 

These gases are produced from organic wastes such as livestock manure, food processing waste, etc.

The process of anaerobic digestion consists of three steps: 

1. The first step is the decomposition (hydrolysis) of plant or animal matter. This step breaks down the organic material to usable-sized molecules such as sugar.
2. The second step is the conversion of decomposed matter to organic acids.
3. Finally, the acids are converted to methane gas.“

 

Anaerobic digesters are machines that anaerobically compost, or “digest” organic waste. Through this process, methane and carbon dioxide are generated with the help of microbes in the waste. The gas produced by the digester is then burned as fuel to make electricity.

An estimated 40 percent of food goes uneaten in the United States. Americans are throwing out the equivalent of $165 billion each year. The uneaten food ultimately ends up rotting in landfills and makes for the single largest component of U.S. municipal solid waste (MSW).

According to the Environmental Protection Agency (EPA), in 2012 Americans threw out roughly 35 million tons of food. “That's almost 20 percent more than Americans tossed out in 2000, 50 percent more than in 1990, and nearly three times what Americans discarded in 1960, when the country threw out a now seemingly paltry 12.2 million tons.”

Since food waste is an excellent feedstock for anaerobic digesters, some, if not most, of the food wasted in America could be diverted from landfills and turned into valuable energy.  The energy produced can be used to heat homes, businesses, and even whole neighborhoods.

There are, of course, pros and cons to building and maintaining anaerobic digesters. Diverting food waste from rotting in landfills, producing an essentially renewable energy source, creating thousands of jobs, and becoming more sustainable are among the pros. The cons include a costly start-up to build the machines, constant maintenance, space to house such large machines, and odors associated with the anaerobic digestion process.

As more grant money is available and more cities begin to develop anaerobic digestion processes to divert food waste out of landfills, jobs can be created, costs of landfilling can be lowered, and America can become a more sustainable country.

For more information on waste and recycling options visit www.wasteawaygroup.com.

energy.ca.gov

nrdc.org

biostrainz.com

energyjustice.net