LARGE SCALE SEWAGE TREATMENT Sewage treatment on a large scale of populations of city is known as Large Scale Sewage Treatment. In Cities, Sewage and Garbage are generated in massive amount per day which is treated by Large Scale Sewage Treatment plants regularly. The principal objective of Wastewater treatment is generally to allow Human and Industrial effluents to be disposed of without danger to human health or unacceptable damage to the natural environment. Overall processes of conventional Large Scale Sewage Treatment plant can be divided into three steps: 1) Primary treatment (Physical method) - Physical separation of Insoluble materials to lower Biological Oxygen Demand (BOD) 2) Secondary treatment (Biological method) - Microbial decomposition of Organic materials in the Effluents. 3) Tertiary treatment (Chemical method) - Chemical removal of inorganic nutrients and pathogenic microbes. 4) Sludge Treatment (Anaerobic digestion of Sludge)