Organics:
Anaerobic Digestion
History
Humans have been capitalizing on Anaerobic Digestion for centuries. Some famous examples include
- As early as 3,000 years ago, biogas Biogas a methane rich gas produced by the anaerobic digestion of animal dung, human sewage and/or organic waste. Biogas also contains carbon dioxide. was used to heat bath water in Assyria
- Starting in 1895, biogas recovered from a sewage treatment facility fueled street lamps in Exeter, Devon.
- In 1951 Germany, biogas from sewage sludge was converted and used for fuel in automobiles.
Present Day
Currently, anaerobic digestion is being used all over the world, and throughout Region 9
- 323 million gallons of sewage flow through The Los Angeles County Joint Plant in Carson each day; this facility uses anaerobic digestion to produce 140,000 metric tons (100% dry weight basis) of biosolidsBiosolids digested solids removed from wastewater., or 575,000 tons on a wet weight basis each year. More information »
- Marin County rancher Albert Straus runs his dairy farm, organic creamery, and electric car, from the manure generated by his herd of 270 cows. More information »
- East Bay Municipal Utility District (EBMUD) uses Anaerobic Digestion to treat 45,000 tons of sludge annually. While the sludge is primarily municipal sewage, they also digest 40 tons of food waste per day. Co-digestingCo-digestion: the simultaneous digestion of a homogenous mixture of two or more substrates. The most common situation is when a major amount of a main basic substrate (e.g. manure or sewage sludge) is mixed and digested together with minor amounts of a single, or a variety of additional substrates (e.g. food waste, yard waste, other putrescibles). these materials yields a whopping 4.5 MW of power annually. This is enough to provide power to about 4,500 homes. See the final report and a fact sheet summarizing EBMUD's project results.
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