Question

What would happen if a large volume of untreated sewage is discharged into a river? 
 

Hint:

High BOD = High water pollution. The BOD test measures the rate of uptake of oxygen by micro-organisms in a sample of water.

Answer 1

Step 1: Discharging untreated sewage increases the organic matter in the water, which leads to a sharp increase in the Biochemical Oxygen Demand (BOD).
Step 2: Microorganisms consume the dissolved oxygen to decompose the organic waste, leading to a decline in Dissolved Oxygen (DO).
Step 3: This lack of oxygen results in the mass mortality of fish and other aquatic organisms, and the water becomes a source of waterborne diseases like Cholera.