Sewage treatment is the process of removing contaminants from wastewater, primarily from household sewage. It includes physical, chemical, and biological processes to remove these contaminants and produce environmentally safe treated wastewater (or treated effluent).

The sewage treatment plant uses chemical, physical, and biological processes to cleanse sewage in order to protect the environment and public health. Sewage treatment is a modern practice, the main reason for constructed sewage is to remove or decrease the dangerous pollutants such as nutrients, carbon inorganic, and organic elements.