Explain the effect on the characteristics of a river when urban sewage is discharged into it
Answers
Answer:
The wastes generated from households – from toilet, kitchen, laundry and other related sources is termed as Domestic sewage. It contains contaminants in the form of disease-causing microbes, suspended solid (clay, salt, sand), colloidal matter (bacteria, plastic, cloth fiber, fecal matter), dissolved matter (phosphate, nitrate, ammonia, sodium, calcium). The organic wastes from the sewage entering the water bodies serve as a source of food for microbes such as bacteria and algae causing these microbes to multiply, hence their population increases. Almost all of the dissolved oxygen is utilized by them for their metabolism leading to the Biological Oxygen Demand (BOD) levels in river water to increase, causing the death of aquatic entities. Additionally, the nutrients present in water cause the planktonic algal growth, hence the algal bloom which leads to the decline in the quality of water and fish mortality.