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Anaerobic Digestion
Anaerobic digestion is a sequence of processes by which microorganisms break down biodegradable material in the absence of oxygen.[1] The process is used for industrial or domestic purposes to manage waste or to produce fuels. Much of the fermentation used industrially to produce food and drink products, as well as home fermentation, uses anaerobic digestion.
Anaerobic digestion occurs naturally in some soils and in lake and oceanic basin sediments, where it is usually referred to as "anaerobic activity".[2][3] This is the source of marsh gas methane as discovered by Alessandro Volta in 1776.[4][5]
The digestion process begins with bacterial hydrolysis of the input materials. Insoluble organic polymers, such as carbohydrates, are broken down to soluble derivatives that become available for other bacteria. Acidogenic bacteria then convert the sugars and amino acids into carbon dioxide, hydrogen, ammonia, and organic acids. In acetogenesis, bacteria convert these resulting organic acids into acetic acid, along with additional ammonia, hydrogen, and carbon dioxide amongst other compounds. Finally, methanogens convert these products to methane and carbon dioxide.[6] The methanogenic archaea populations play an indispensable role in anaerobic wastewater treatments.[7]
Anaerobic digestion 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.[8]
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.[1] This biogas can be used directly as fuel, in combined heat and power gas engines[9] or upgraded to natural gas-quality biomethane. The nutrient-rich digestate also produced can be used as fertilizer.
With the re-use of waste as a resource and new technological approaches that 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),[10] Germany,[citation needed] Denmark (2011),[11] and the United States.[12]
Bournemouth (/ˈbɔːrnməθ/ ⓘ BORN-məth) is a coastal resort town on the south coast in the Bournemouth, Christchurch and Poole unitary authority area in the ceremonial county of Dorset, England. The town's urban subdivision had a population of 187,503 at the 2011 census making it the largest town in the county; the town is part of the South East Dorset conurbation, which has a population of 465,000.
Founded in 1810 by Lewis Tregonwell, in an area of deserted heathland occasionally visited by fishermen and smugglers, as a health resort,[1] Bournemouth became a town in 1870, with growth from the arrival of the railway. Bournemouth lies in the historic county of Hampshire. Following the local government reorganisation in 1974 the town was transferred to the county of Dorset, governed by Dorset County Council. Although the borough gained unitary authority in 1997, it retained Dorset's ceremonial county functions and emergency services. In April 2019, the borough was replaced by the current borough, also with unitary authority status, governing the town, Poole, Christchurch and surrounding areas.
Victorian architecture is notable in the town centre. The 202-foot (62 m) spire of St Peter's Church, one of three Grade I listed churches in the borough, is a local landmark. The town's location has made it a popular destination for tourists, attracting over five million visitors annually with its beaches and popular nightlife. It is also a regional centre of business, home of the Bournemouth International Centre (BIC) and a financial sector that is worth more than £1 billion in gross value added.
