Wastewater treatment is the most common method used to recover purified water from wastewater or sewage. that treated water can be returned into the water cycle. Treated effluent creates an acceptable impact on the environment or it can be reused for different purposes.

There are two types of wastewater domestic and industrial. The wastewater is treated at suitable wastewater treatment plants (WWTP). For domestic wastewater (Municipal Wastewater), the treatment plant is known as a Sewage Treatment Plant(STP). Industrial wastewater treatment is in a mechanical wastewater treatment plant or a sewage treatment plant. Wastewater treatment is essential for the sanitation sector. Sanitation includes human waste and solid waste management as well as rainwater (drainage) management.

Wastewater generates from various sources, such as sanitary and domestic wastewater, commercial and institutional wastewater, manufacturing and industrial wastewater, construction wastewater, and stormwater.

Wastewater treatment removes contaminants from wastewater before it is discharged into a water body. Physical processes like sedimentation and filtration, chemical processes like precipitation, and biological processes like aerated lagoons or activated sludge systems are under this category.

Conventional wastewater treatment consists of combining physical, chemical, and biological processes and operations to remove solids, organic matter, and nutrients from wastewater. General terms used to describe different steps of wastewater treatment, in order of increasing treatment level, are preliminary, primary, secondary, tertiary, and advanced wastewater treatment.

Specifically, in the water industry, recover wastewater and turn it into a valuable source while limiting waste production. Water treatment facilities contribute significantly to the circular economy by creating clean water, fertilizers, renewable energy, and other functional bio-based materials. Water treatment facilities offer a unique potential to reduce energy needs, minimize costs, and improve renewable energy production by producing valuable resources from waste streams. These resources include water, energy, nutrients (phosphorus and nitrogen), and biosolids.