OPSC 2017 Solved Paper

Biochemical Oxygen Demand (BOD, also called Biological Oxygen Demand) is the amount of dissolved oxygen needed (i.e. demanded) by aerobic biological organisms to break down organic material present in a given water sample at certain temperature over a specific time period. Microorganisms such as bacteria are responsible for decomposing organic waste. It a pond ecosystem, the BOD increase due to increase in the population of bacteria.