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 safer treated wastewater (or treated effluent).
Municipal wastewater treatment plant cleans sewage and water so that they can be returned to the environment. Wastewater treatment plants remove solids and pollutants, break down organic matter and restore the oxygen content of treated water.
Drinking water must be free of suspended solids, microorganisms and toxic chemicals. Mineral concentration recommendation vary from country to country but most of the minerals have a maximum concentration recommended to ensure safe, equilibrated and pleasant water to drink.