Question

Multiple Choice Questions
BOD in river water

• A. Remains unchanged when algal bloom occurs
• B. Increases when sewage gets mixed up with river water
• C. Has no relationship with concentration of oxygen in water
• D. Give a measure for Salmonella in water.

Answer 1

The correct option is B Increases when sewage gets mixed up with river water

Biochemical Oxygen Demand or BOD is the amount of dissolved oxygen needed by aerobic microbes to break down organic matter present in a particular water sample at a certain temperature over a specified period of time. Value of BOD increases, given that the organic matter content is high in the water sample. Sewage is rich in organic residues thus it increases BOD of river water upon mixing.

So, the correct answer is option B, increases when sewage gets mixed up with river water.