Sewage treatment plant (WWTP)

A sewage treatment plant (WWTP), also known as waste water treatment plant (AWZI), treats the waste water from households and businesses that is supplied via the sewer. In a sewage treatment plant, waste water is treated from sewers before entering surface water. The incoming dirty water, the influent, is purified in the plant in a number of steps. The purified water is called the effluent. Successively removes the coarser particles with a grate or a separator, than the finer particles in settling tanks, and finally the dissolved substances. In addition to water, other substances are released, in particular sludge, which is sometimes redeployed. Waste water treatment is governed by national and international regulations.