Wastewater refers to any water that is not clean or is adversely affected in quality by human-induced activities. Wastewater originates from a combination of domestic, industrial, commercial, or agricultural activities.
Wastewater treatment or management refers to the processes used to convert wastewater into an effluent that can be either returned to the water cycle with negligible environmental impact or can be reused.
The major objective of wastewater treatment is generally to allow human and industrial effluents to be disposed of without danger to human health or unacceptable damage to the natural environment.
Phase Separation − It transfers impurities into a non-aqueous phase.
Sedimentation − Sedimentation is a physical water treatment process using gravity to remove suspended solids from water. Solid particles entrained by the turbulence of moving water may be removed naturally by sedimentation in the still water of lakes and oceans.
Filtration − Suspension of fine solids may be removed by filtration through physical barriers such as coarser screens or sieves.
Oxidation − This process diminishes the biochemical oxygen demand of wastewater and may reduce the toxicity of some impurities. Advanced Oxidation Processes (AOPs) are a set of chemical treatment of wastewater purported to remove organic and also inorganic materials in waste water by oxidation through reaction with hydroxyl radicals.
Chemical oxidation may remove some persistent organic pollutants and concentrations remaining after biochemical oxidation.
Wastewater treatment plants are set up for effective treatment of wastewater. They may be distinguished by the type of wastewater to be treated. They are as follows.