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Organics: Anaerobic Digestion
Benefits
Anaerobic Digestion produces 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.. Biogas is a combination of methane and carbon dioxide. Biogas gas can be captured for energy rather than released into to the environment. The methane is burned as an energy source, which means only CO2 is emitted. Methane, the largest anthropogenic source of which is landfills, is a greenhouse gas Greenhouse Gases that trap the heat of the sun in the Earth's atmosphere, producing the greenhouse effect. The two major greenhouse gases are water vapor and carbon dioxide. Other greenhouse gases include methane, ozone, chlorofluorocarbons, and nitrous oxide. 21x times more powerful than CO2.
Anaerobically digesting food waste and yard scraps prevents these materials from being sent to landfills; and the resultant biogas from anaerobic digestion can be harvested over a matter of weeks as opposed to decades.
Biogas is an alternative to using gas or coal as an energy source. Natural gas and coal emit greater quantities of greenhouse gases and other pollutants than biogas.
Anaerobic Digestion plants require less physical space than aerobic composting facilities. Comparatively smaller AD plants can reserve land for other purposes.
When material like food waste, manure, or sewage is anaerobically digested rather than trucked greater distances to a landfill, the associated transportation emissions are reduced.
Diverting organic waste from the landfill also reduces the production of leachateLeachate Water that collects contaminants as it trickles through wastes, pesticides or fertilizers. In landfills, leaching can occur and may result in hazardous substances entering surface water, ground water, or soil in the landfill.
Another byproduct of the anaerobic digestion process is acidogenicAcidogenesis The process by which simple monomers are converted into volatile fatty acids. digestateDigestate The "liquid" byproduct of the anaerobic digestion process., which is a lot like compostCompost decomposed organic material produced when naturally occurring bacteria break down organic waste, resulting in a nutrient rich soil amendment.. The byproduct is a valuable soil amendment that, when added to soil, can improve plant growth, reduce soil erosion and nutrient run-off, alleviate soil compaction, and help soil retain water.
Using the digestate can also reduce the need for chemical fertilizers. Not using chemical fertilizers further reduces greenhouse gas emissions, which are emitted during the chemical fertilizer manufacturing process.
