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A marine outfall is a pipeline or tunnel that discharges municipal or industrial wastewater, stormwater, combined sewer overflows, cooling water, or brine effluents from water desalination plants to the sea. Usually they discharge under the sea's surface (submarine outfall). In the case of municipal wastewater, effluent is often being discharged after having undergone no or only primary treatment, with the intention of using the assimilative capacity of the sea for further treatment. Submarine outfalls are common throughout the world and probably number in the thousands. More than 200 outfalls alone have been listed in a single international database maintained by the Institute for Hydromechanics at Karlsruhe University for the International Association of Hydraulic Engineering and Research (IAHR) / International Water Association (IWA) Committee on Marine Outfall Systems.〔(Outfalls Database ) Click on "Activities", then "Outfalls repository", then "database", then "Output"〕 The World's first marine outfall was built in Santa Monica, United States, in 1910. In Latin America and the Caribbean there were 134 outfalls with more than 500 m length in 2006 for wastewater disposal alone, according to a survey by the Pan American Center for Sanitary Engineering and Environmental Sciences (CEPIS) of PAHO. According to the survey, the largest number of municipal wastewater outfalls in the region exist in Venezuela (39), Chile (39) and Brazil (22). The World's largest marine outfall is located in Boston, United States.〔http://www.bwsc.org/about_bwsc/systems/outfall_maps/outfall_maps.asp〕Currently, Boston has approximately 235 miles of combined sewers and 37 active CSO outfalls. Lots of outfalls are simply known by a public used name, e.g. Boston Outfall.〔(OUTFALLS DATABASE AND INFORMATION EXCHANGE )〕〔http://www.bwsc.org/ABOUT_BWSC/systems/outfall_maps/CSO_INNERHARBOR.pdf〕〔http://www.bwsc.org/ABOUT_BWSC/systems/outfall_maps/CSO_DORCHESTERBAY.pdf〕〔http://www.bwsc.org/ABOUT_BWSC/systems/outfall_maps/CSO_CHARLES.pdf〕 == Advantages == According to the Australian engineer Sharon Beder the main advantages of marine outfalls for the discharge of wastewater are: *the natural dilution and dispersion of organic matter, pathogens and other pollutants *the ability to keep the sewage field submerged because of the depth at which the sewage is being released *the greater die-off rate of pathogens due to the greater distance they will have to travel to shore.〔Beder, Sharon: (From Pipe Dreams to Tunnel Vision: Engineering Decision-Making and Sydney's Sewerage System ), Ph.D. Thesis, UNIVERSITY OF NEW SOUTH WALES, AUSTRALIA 1989, Chapter 8: The 'Science' and 'Metaphysics' of Submarine Outfalls〕 They also tend to be less expensive than advanced wastewater treatment plants, using the natural assimilative capacity of the sea instead of energy-intensive treatment processes in a plant. For example, preliminary treatment of wastewater is sufficient with an effective outfall and diffuser. The costs of preliminary treatment are about one tenth that of secondary treatment.〔Philip JW Roberts:"Underwater and underused: The case of marine outfalls in wastewater disposal", in Water21, Magazine of the International Water Association, October 2010, pp. 22-26〕 Preliminary treatment also requires much less land than advanced wastewater treatment. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Marine outfall」の詳細全文を読む スポンサード リンク
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