A wastewater treatment plant(wwtp plant) or Wastewater Treatment Plant Effluent cleans sewage and water so that they can be returned to the environment. These plants remove solids and pollutants, break down organic matter and restore the oxygen content of treated water. They achieve these results through four sets of operations: preliminary, primary, secondary and sludge treatments. Normally, a network of sewers connected to homes, commercial buildings, schools and street grates delivers waste water and solids to a treatment plant's collection tanks and basins in a never-ending flow. Effluent treatment plant and wastewater treatment was also called etp and wwtp plant.The Activated Sludge Process (ASP) is a sewage treatment process or Sewage and effluent treatment plant, in which air or oxygen is blown into raw, unsettled sewage to smash the solids and develop a biological 'soup' which digests the organic content and pollutants in the sewage. These plants do not have a primary settlement chamber which is the chamber that needs emptying by tanker on a regular basis with most three stage sewage treatment plants and effluent treatment and wastewater treatment, industrial effluent wastewater treatment.

• Rigid construction