<P> Sewage treatment is the process of removing contaminants from wastewater, primarily from household sewage . Physical, chemical, and biological processes are used to remove contaminants and produce treated wastewater (or treated effluent) that is safer for the environment . A by - product of sewage treatment is usually a semi-solid waste or slurry, called sewage sludge . The sludge has to undergo further treatment before being suitable for disposal or application to land . </P> <P> Sewage treatment may also be referred to as wastewater treatment . However, the latter is a broader term which can also refer to industrial wastewater . For most cities, the sewer system will also carry a proportion of industrial effluent to the sewage treatment plant which has usually received pre-treatment at the factories themselves to reduce the pollutant load . If the sewer system is a combined sewer then it will also carry urban runoff (stormwater) to the sewage treatment plant . Sewage water can travel towards treatment plants via piping and in a flow aided by gravity and pumps . The first part of filtration of sewage typically includes a bar screen to filter solids and large objects which are then collected in dumpsters and disposed of in landfills . Fat and grease is also removed before the primary treatment of sewage . </P>

What is the process of sewage treatment plant
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