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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]
Kingston upon Hull, usually shortened to Hull, is a port city and unitary authority area in the East Riding of Yorkshire, England.[2] It lies upon the River Hull at its confluence with the Humber Estuary, 25 miles (40 km) inland from the North Sea and 37 miles (60 km) south-east of York, the historic county town.[2] With a population of 268,852 (2022), it is the fourth-largest city in the Yorkshire and the Humber region after Leeds, Sheffield and Bradford.
The town of Wyke on Hull was founded late in the 12th century by the monks of Meaux Abbey as a port from which to export their wool. Renamed Kings-town upon Hull in 1299, Hull had been a market town,[3] military supply port,[4] trading centre,[5] fishing and whaling centre and industrial metropolis.[4] Hull was an early theatre of battle in the English Civil Wars.[5] Its 18th-century Member of Parliament, William Wilberforce, took a prominent part in the abolition of the slave trade in Britain.[6]
More than 95% of the city was damaged or destroyed in the blitz and suffered a period of post-industrial decline (social deprivation, education and policing).[7] The destroyed areas of the city were rebuilt in the post–Second World War period.[8] In the early 21st century spending boom before the late 2000s recession the city saw large amounts of new retail, commercial, housing and public service construction spending.
In 2017, it was the UK City of Culture and hosted the Turner Prize at the city's Ferens Art Gallery.[9] Other notable landmarks in the city are the Minster, the tidal surge barrier, the Paragon Interchange and The Deep aquarium. Areas of the town centre include the old town (including its museum quarter) and the marina. Hull University was founded in 1927 and had over 16,000 students in 2022.[10] Rugby league football teams include clubs Hull F.C. and Hull Kingston Rovers. The city's association football club is Hull City (EFL Championship). Hull RUFC and Hull Ionians both play in the National League 2 North of rugby union.
