What is sewage ? From what sewage water is passed before disposing?

Explanation

Large quantities of waste water are generated everyday in cities and towns. A major component of this waste water is human excreta. This municipal waste water is also called sewage. It contains large amount of organic matter and microbes. Many of which are pathogenic. This urban waste water cannot be discharged into natural water bodies like rivers and streams directly. Sewage is treated in sewage treatment plants (STPs) to make it less polluting. Treatment of waste water is done by the heterotrophic microbes naturally present in the sewage.