How is wastewater treated in a wastewater treatment plant?

Wastewater is treated in a wastewater treatment plant by first passing it through a series of steps called physical, chemical and biological processes. In the physical process, screens and grit chambers remove large particles such as plastics, rags and gravel.

The chemical process involves the addition of chemicals such as alum to separate out particles, while the biological process uses microbes to break down organic material into harmless end products. Finally, the treated water is disinfected with chlorine or ultraviolet light to kill bacteria and other microorganisms before the water is released back into the environment.