Description

Wastewater treatment is a process used to remove contaminants from Wastewater
or sewage and convert it into an effluent that can be returned to the water cycle
with minimum impact on the environment, or directly reused. The latter is called
water reclamation because treated wastewater can be used for other purposes.
The treatment process takes place in a wastewater treatment plant (WWTP), often
referred to as a Water Resource Recovery Facility (WRRF) or a sewage treatment
plant (STP). Pollutants in municipal wastewater (households and small industries)
are removed or broken down.
The treatment of wastewater is part of the overarching field of sanitation.
Sanitation also includes the management of human waste and solid waste as well
as drainage management. By-products from wastewater treatment plants, such as
screenings, grit, and sewage sludge may also be treated in a wastewater treatment
plant.
Although disposal or reuse occurs after treatment, it must be considered first. Since
disposal or reuses are the objectives of wastewater treatment, disposal or reuse
options are the basis for treatment decisions. Acceptable impurity concentrations
may vary with the type of use or location of disposal. Transportation costs often
make acceptable impurity concentrations dependent upon the location of disposal, but
expensive treatment requirements may encourage the selection of a disposal location
on the basis of impurity concentrations. Ocean disposal is subject to international
treaty requirements. International treaties may also regulate disposal into rivers
crossing international borders.
Water bodies entirely within the jurisdiction of a single nation may be subject to
regulations of multiple local governments. Acceptable impurity concentrations may
vary widely among different jurisdictions for disposal of wastewater to
evaporation ponds, infiltration basins, or injection wells.