Sewage Treatment Plants

A Sewage Treatment Plant (STP) treats the sewage produced from various establishments to make it safe for disposal. It performs physical, chemical, and biological processes to remove contaminants and produce treated wastewater that is safe enough to dispose of into the environment.The basic principle of the working of a biological treatment plant is decomposition of the raw sewage. This process is done by aerating the sewage chamber with fresh air. The aerobic bacteria survive on this fresh air and decompose the raw sewage which can be disposed of in the sea.In a sewage treatment plant, sewage water is first allowed to pass through screens or grit chamber where large solids are removed. This step is followed by aeration/mixing in a tank and then primary sedimentation where suspended solids settle down.1) Aeration tank containing micro organisms in suspension in which reaction takes place. 2) Activated sludge recirculation system. 3) Excess sludge wasting and disposal facilities. 4) Aeration systems to transfer oxygen 5) Secondary sedimentation tank to separate and thicken activated sludge.