Question

give the chart of a physical sewage system .

Answer 1

Sewage or municipal waste should not be directly passed into rivers, streams and other water bodies because it not only contains human excreta and other organic wastes but a number of pathogenic microbes. It is made less polluting by passing it through sewage treatment plants (STPs).Here heterotrophic microbes naturally present in sewage carry out the process of decomposition. There are three stages of this treatment; primary, second­ary and tertiary. Primary treatment is physical, secondary biological and tertiary chemical. Waste water can be passed into rivers after sec­ondary treatment.