Anaerobic Digestion

Anaerobic digestion is a series of processes in which microorganisms break down biodegradable material in the absence of oxygen. It is used for industrial or domestic purposes to manage waste and/or to release energy. Much of the fermentation used industrially to produce food and drink products, as well as home fermentation, uses anaerobic digestion. Silage is produced by anaerobic digestion.

The digestion process begins with bacterial hydrolysis of the input materials to break down insoluble organic polymers, such as carbohydrates, and make them available for other bacteria. Acidogenic bacteria then convert the sugars and amino acids into carbon dioxide, hydrogen, ammonia, and organic acids. Acetogenic bacteria then convert these resulting organic acids into acetic acid, along with additional ammonia, hydrogen, and carbon dioxide. Finally, methanogens convert these products to methane and carbon dioxide. The methanogenic archaea populations play an indispensable role in anaerobic wastewater treatments.

It is used as part of the process to treat biodegradable waste and sewage sludge. As part of an integrated waste management system, anaerobic digestion reduces the emission of landfill gas into the atmosphere. Anaerobic digesters can also be fed with purpose-grown energy crops, such as maize.

Anaerobic digestion is widely used as a source of renewable energy. The process produces a biogas, consisting of methane, carbon dioxide and traces of other ‘contaminant’ gases. This biogas can be used directly as cooking fuel, in combined heat and power gas engines or upgraded to natural gas-quality biomethane. The use of biogas as a fuel helps to replace fossil fuels. The nutrient-rich digestate also produced can be used as fertilizer.

Anaerobic digestion facilities have been recognized by the United Nations Development Programme as one of the most useful decentralized sources of energy supply, as they are less capital-intensive than large power plants. With increased focus on climate change mitigation, the re-use of waste as a resource and new technological approaches which have lowered capital costs, anaerobic digestion has in recent years received increased attention among governments in a number of countries, among these the United Kingdom (2011), Germany and Denmark (2011).

Read more about Anaerobic Digestion:  History, Process, Feedstocks, Applications

Other articles related to "anaerobic digestion, anaerobic, digestion":

Balage - Anaerobic Digestion
... Silage is a useful feedstock for anaerobic digestion ... Here silage can be fed into anaerobic digesters to produce biogas that, in turn, can be used to generate electricity and heat ...
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... Anaerobic digestion can minimize odor, generate biogas, and allow more effective nutrient use by crops ... To realize the potential energy, environmental, and cost saving benefits of anaerobic digestion, farmers need information to evaluate the energy, labor, land, and equipment costs ... sn The anaerobic digester project at SUNY Morrisville involves the design and construction of a hardtop plug-flow digester ...
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... The final output from anaerobic digestion systems is water, which originates both from the moisture content of the original waste that was treated and water produced during the ... The wastewater exiting the anaerobic digestion facility will typically have elevated levels of biochemical oxygen demand (BOD) and chemical oxygen demand (COD) ... is termed 'hard COD', meaning it cannot be accessed by the anaerobic bacteria for conversion into biogas ...
Sewage Sludge Treatment - Digestion - Anaerobic Digestion
... Anaerobic digestion is a bacterial process that is carried out in the absence of oxygen ... The process can either be thermophilic digestion in which sludge is fermented in tanks at a temperature of 55°C or mesophilic, at a temperature of around 36°C ... retention time, thus smaller tanks, thermophilic digestion is more expensive in terms of energy consumption for heating the sludge ...
Food Waste In The United Kingdom - History
... Five flagship anaerobic digestion plants that will demonstrate "cutting-edge technology" are to be built before the end of March 2011 they will together receive a grant of £10 million from WRAP's "Anaerobic ... Between them, they demonstrate how anaerobic digestion can help the UK efficiently meet the challenges of reducing carbon emissions and improving ...

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