Conventional septic systems for household waste treatment consist of a septic tank and drain field. This simple technology allows wastes to be disposed of in a manner that minimizes noxious odors, surface contamination, and spread of waterborne diseases. Effluent entering groundwater from septic systems often contains nitrate, phosphate, fecal indicators, and micropollutants such as personal care products, caffeine, pharmaceuticals and hormones. Advanced treatment systems are used in cases where drain fields are not effective due to high water tables or low soil porosity, in densely populated areas, and in environmentally sensitive areas. Examples of improvements to traditional septic systems that are considered to be advanced or alternative technologies include modifications to the tank, the incorporation of filters such as sand filters, the addition of aerobic, anaerobic, and/or electrochemical treatment units, and improvement to drain fields by addition of wood chips and/or other microbial substrates. These modified septic systems are capable of expanding the range of housing sites for which septic systems can provide effective waste treatment, as well as providing more complete removal of contaminants in environmentally sensitive areas.
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