Question

Explain the effect on the characteristics of a river when urban sewage is discharged into it.

Answer 1

Discharge of urban sewage will lead to a drastic increase in the BOD of the river. Due to the discharge of urban sewage into the river body, growth of micro-organisms involved in the degradation of organic sewage by utilising oxygen rapidly increases, leading to a huge increase in the BOD (Biological Oxygen Demand) of the river body. This will also generate anoxygenic conditions within the river body leading to the widespread death of aquatic lifeforms, resulting in the destruction of the aquatic ecosystem and degrading the water quality of the river.