What are the various constituents of domestic sewage? Discuss the effects of sewage discharge on a river.

(N/A) Domestic sewage is the waste originating from the kitchen,toilet,laundry,and other sources. It contains impurities such as suspended solids (sand,salt,clay),colloidal materials (fecal matter,bacteria,plastic,and cloth fibers),dissolved materials (nitrates,phosphates,calcium,sodium,ammonia),and disease-causing microbes.
When organic wastes from the sewage enter water bodies,they serve as a food source for microorganisms such as algae and bacteria. As a result,the population of these microorganisms in the water body increases. They utilize most of the dissolved oxygen for their metabolism. This leads to an increase in the levels of Biological Oxygen Demand $(BOD)$ in river water,resulting in the death of aquatic organisms. Additionally,the nutrients in the water lead to the growth of planktonic algae,causing algal blooms,which cause the deterioration of water quality and fish mortality.