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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]
Watford (/ˈwɒtfərd/ ⓘ) is a town and borough in Hertfordshire, England, 15 mi (24 km) north-west of Central London, on the banks of the River Colne.
Initially a small market town, the Grand Junction Canal encouraged the construction of paper-making mills, print works, and breweries. While industry has declined in Watford, its location near London and transport links have attracted several companies to site their headquarters in the town. Cassiobury Park is a public park that was once the manor estate of the Earls of Essex.
The town developed next to the River Colne on land belonging to St Albans Abbey. In the 12th century, a charter was granted allowing a market, and the building of St Mary's Church began. The town grew partly due to travellers going to Berkhamsted Castle and the royal palace at Kings Langley. A mansion was built at Cassiobury in the 16th century. This was partly rebuilt in the 17th century and another country house was built at The Grove.
Clarendon Road, Watford
Clarendon Road
The Grand Junction Canal in 1798 and the London and Birmingham Railway in 1837 resulted in Watford's rapid growth, with paper-making mills such as John Dickinson at Croxley, influencing the development of printing in the town. Two brewers, Benskins and Sedgwicks, amalgamated and flourished in the town until their closure in the late 20th century. Hertfordshire County Council designates Watford to be a major sub-regional centre. Several head offices are based in Watford. International conferences and sporting events have also taken place in Watford, including the 2006 World Golf Championship, the 2013 Bilderberg Conference and the 2019 NATO summit which all took place at The Grove.[2]
Watford became an urban district under the Local Government Act 1894 and a municipal borough by grant of a charter in 1922. The borough, which had 102,246 inhabitants in the 2021 census (up from 90,301 inhabitants at the 2011 census, an increase of 13.23%), is separated from Greater London to the south by Three Rivers District. Watford Borough Council is the local authority with the Mayor of Watford as its head – one of only 18 directly elected mayors in England and Wales.
