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An aerobic treatment system or ATS, often called (incorrectly) an aerobic septic system, is a small scale sewage treatment system similar to a septic tank system, but which uses an aerobic process for digestion rather than just the anaerobic process used in septic systems. These systems are commonly found in rural areas where public sewers are not available, and may be used for a single residence or for a small group of homes. Unlike the traditional septic system, the aerobic treatment system produces a high quality secondary effluent, which can be sterilized and used for surface irrigation. This allows much greater flexibility in the placement of the leach field, as well as cutting the required size of the leach field by as much as half.〔U.S. Environmental Protection Agency (EPA), Washington, D.C. (2002). ("Onsite Wastewater Treatment Systems Manual." ) Document No. EPA-625-R-00-008.〕 ==Process== The ATS process generally consists of the following phases: *Pre-treatment stage to remove large solids and other undesirable substances from the wastewater; this stage acts much like a septic system, and an ATS may be added to an existing septic tank to further process the primary effluent. *Aeration stage, where the aerobic bacteria digest the biological wastes in the wastewater. *Settling stage to allow any undigested solids to settle. This forms a sludge which must be periodically removed from the system. *Disinfecting stage, where chlorine or similar disinfectant is mixed with the water, to produce an antiseptic output. The disinfecting stage is optional, and is used where a sterile effluent is required, such as cases where the effluent is distributed above ground. The disinfectant typically used is tablets of calcium hypochlorite, which are specially made for waste treatment systems.〔EPA (2003). ("Disinfection for Small Systems." ) Wastewater Technology Fact Sheet. Document No. EPA 832-F-03-024.〕 Unlike the chlorine tablets used in swimming pools, which is stabilized for resistance to breakdown in ultraviolet light, the tablets used in waste treatment systems is intended to break down quickly in sunlight. Stabilized forms of chlorine will persist after the effluent is dispersed, and can kill off plants in the leach field. Since the ATS contains a living ecosystem of microbes to digest the waste products in the water, excessive amounts of items such as bleach or antibiotics can damage the ATS environment and reduce treatment effectiveness. Non-digestible items should also be avoided, as they will build up in the system and require more frequent sludge removal.〔(Items to Avoid ), Hoot Aerobic Systems〕 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「Aerobic treatment system」の詳細全文を読む スポンサード リンク
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