Biological Wastewater treatment is a process that uses natural processes of all living organisms to treat contaminated water. Its a complex process that takes place in the intersection of biology and biochemistry.Biological wastewater treatment harnesses the action of bacteria and other microorganisms to clean water.The Biological wastewater treatment plant cleans water in three stages. In the first stage, water is channeled to a settling tank and allowed to circulate, which causes some of the solid waste particles to settle out. In the second stage, water is treated at an aeration tank before moving on to the clarifier. Here, oxygen levels are moderated, living organisms consume the sewage, and remaining solid waste sinks to bottom and can be taken away.