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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]
Colwick (/ˈkɒlɪk/ KOL-ik) is a village and civil parish, in the Borough of Gedling of Nottinghamshire, England. It is situated to the east of Nottingham's city boundary, and forms the Colwick ward. At the time of the 2011 census, the village had a population of 2,829, falling to 2,778 at the 2021 census.
The village is recorded in the Domesday Book of 1086,[4] since when the De-Colwick,Musters and Byron families have all owned the village. The etymology of the place-name is from Old English wic "specialised industrial farm" with an uncertain first element, possibly col "coal",[citation needed] although there have never been coal mines in the area. Another derivation is from the area being a dairy farm.
In 1844 there was a gruesome murder at 'Saville's Spinney', then part of Colwick Park and later part of Colwick Woods. William Saville murdered his wife and three children in the woods on Tuesday 21 May. Their bodies were found one day later by John Swinscoe of Carlton who fetched the parish constable to the spot. An open razor was found in the left hand of the dead woman. The crowd for Saville's execution numbered in the tens of thousands and twelve died in a panic in the moments after Saville was executed.
