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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]
Poole (/puːl/ (audio speaker iconlisten)) is a large coastal town and seaport in Dorset, on the south coast of England. The town is 21 miles (34 km) east of Dorchester and adjoins Bournemouth to the east. Since 1 April 2019, the local authority is Bournemouth, Christchurch and Poole Council which is a unitary authority. Poole had an estimated population of 151,500 (mid-2016 census estimates) making it the second-largest town in the ceremonial county of Dorset. Together with Bournemouth and Christchurch, the conurbation has a total population of nearly 400,000.
Human settlement in the area dates back to before the Iron Age. The earliest recorded use of the town's name was in the 12th century when the town began to emerge as an important port, prospering with the introduction of the wool trade. Later, the town had important trade links with North America and, at its peak during the 18th century, it was one of the busiest ports in Britain. In the Second World War, Poole was one of the main departing points for the Normandy landings.
Poole is a tourist resort, attracting visitors with its large natural harbour, history, the Lighthouse arts centre and Blue Flag beaches. The town has a commercial port with cross-Channel freight and passenger ferry services, which connect with the Channel Islands of Jersey and Guernsey, as well as the French port town of Saint-Malo, Brittany.
The headquarters of the Royal National Lifeboat Institution (RNLI) is in Poole, and the Royal Marines have a base in the town's harbour. Despite their names, Poole is the home of The Arts University Bournemouth, the Bournemouth Symphony Orchestra and a significant part of Bournemouth University.
