{"id":213793,"date":"2022-01-26T16:59:10","date_gmt":"2022-01-26T15:59:10","guid":{"rendered":"https:\/\/www.ferrovial.com\/?page_id=213793"},"modified":"2022-09-22T18:54:48","modified_gmt":"2022-09-22T16:54:48","slug":"septic-tank","status":"publish","type":"page","link":"https:\/\/www.ferrovial.com\/en\/resources\/septic-tank\/","title":{"rendered":"Septic tank"},"content":{"rendered":" \n \n
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  1. Ferrovial<\/a><\/li>\n
  2. Resources<\/a><\/li>\n \n <\/ol>\n\n <\/c-breadcrumb>\n \n
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    \n Septic tank <\/h1>\n <\/div>\n <\/m-final-content-header>\n\n \n\n\n
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    What is a septic tank?<\/h2>\n\n\n\n

    Septic tanks are secure systems for storing and subsequently disposing of fecal waste. A simple decantation and sedimentation process eliminates any solids in the wastewater, thus preventing them from contaminating the soil or freshwater sources.<\/p>\n\n\n\n

    Septic tanks are very common in rural areas that aren’t on a municipal sewer network. Concrete or cement, fiberglass, plastic or high-density polyethylene, and steel can be used to build one. There are currently also prefabricated tanks that can be used as a temporary solution.<\/p>\n\n\n\n

    How does a septic tank work?<\/h2>\n\n\n\n

    To create a septic tank, a small well is dug, and a tank is built inside it. The wastewater generated in a house, group of houses, public toilets, rural school, or any other building that’s far away from a sewer system can be drained into it. There are one-chamber and two-chamber septic tanks, and each type works differently.<\/p>\n\n\n\n

    Single-chamber septic tanks:<\/strong><\/p>\n\n\n\n

    Gray wastewater (from kitchens, bathrooms, or laundry rooms) and black wastewater (from latrines or bathrooms) flow into the tank through a pipe. There, they separate and settle out, with content floating to the surface or sinking to the bottom, forming sludge and sediment. The sediments trapped in the tank are digested<\/em> and reduced by anaerobic fermentation, which causes the formation of gases like carbon dioxide (CO2) and ammonium (NH4).<\/p>\n\n\n\n

    Two-chamber septic tank: <\/strong><\/p>\n\n\n\n

    During the decantation and sedimentation process in the first chamber, the separated effluents flow into a second chamber. These waters are not completely purified since they still contain bacterial germs; they have gone through a pre-treatment process that lets about 30% of carbon pollution be eliminated. This means that, under certain specific conditions, it is possible to evacuate the water from the second chamber to ceramic drains, cesspools, irrigation fields, sand beds, or mini purification stations that use bacterial filters. However, this is prohibited in many countries to prevent contamination, foul odors, and other complications. <\/p>\n\n\n\n

    How is a septic tank’s operation optimized?<\/h2>\n\n\n\n