Jobs
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]
Peterborough (/ˈpiːtərbərə, -ˌbʌrə/ (About this soundlisten)) is a cathedral city in Cambridgeshire, England, with a population of 202,110 in 2017.[5] Historically part of Northamptonshire, it is 76 miles (122 km) north of London, on the River Nene which flows into the North Sea 30 miles (48 km) to the north-east. The railway station is an important stop on the East Coast Main Line between London and Edinburgh. Peterborough is also the largest city and borough in Cambridgeshire and the East Anglia area of England.
The local topography is flat, and in some places the land lies below sea level, for example in parts of the Fens to the east of Peterborough. Human settlement in the area began before the Bronze Age, as can be seen at the Flag Fen archaeological site to the east of the current city centre, also with evidence of Roman occupation. The Anglo-Saxon period saw the establishment of a monastery, Medeshamstede, which later became Peterborough Cathedral.
The population grew rapidly after the railways arrived in the 19th century, and Peterborough became an industrial centre, particularly known for its brick manufacture. After the Second World War, growth was limited until designation as a New Town in the 1960s. Housing and population are expanding and a £1 billion regeneration of the city centre and immediately surrounding area is under way. Industrial employment has fallen since then, a significant proportion of new jobs being in financial services and distribution.
