Question

Biochemical oxygen demand(BOD) is the amount of oxygen required(in ppm):
(A)for the photochemical breakdown of waste present in the volume of a water body
(B)by bacteria to breakdown organic waste in a certain volume of a water sample
(C)for sustaining life in a water body
(D)by anaerobic bacteria to break down inorganic waste present in a water body

Answer 1

The biochemical oxygen demand is a parameter of judging the quality of the water. Depending on the quantity of biological oxygen demand, the quality of water can be determined.

Complete solution:
We know that biochemical oxygen demand refers to the amount of oxygen required for the complete decomposition of organic matter present in the water body by decomposing bacteria. Higher the level of BOD higher will be the level of pollution in the water body.
It is defined as the amount of oxygen consumed by bacteria along with other microorganisms while they decompose on the organic mass matter under anaerobic conditions at a defined temperature. A value of biochemical oxygen demand means a high amount of oxygen is required by bacteria to decompose the organic matter. So the amount of organic matter present in water is also high. So biological oxygen demand is the amount of oxygen required by bacteria to break down organic waste in a certain volume of a water sample.

Thus, the correct option is (D).

Additional Information: Poorly treated wastewater results in higher levels of Biochemical oxygen demand. This allows less oxygen for the aquatic species.

Note: Biochemical oxygen demand is used in wastewater treatment plans. It tells us the amount of organic pollution in water. Chemical oxygen demand(COD) is also a way to measure the quality of water. Here the amount of oxygen required for chemical oxidation of organic matter is determined. In all both cases chemical oxygen demand is less than biological oxygen demand.