Question

How is Biochemical Oxygen Demand (BOD) different from Chemical Oxygen Demand (COD)?

Answer 1

The oxygen required by bacteria and other microorganisms while disintegrating organic compounds during aerobic conditions at a particular temperature is referred to as biochemical oxygen demand (BOD). The chemical oxygen demand (COD) is a rough estimate of how much oxygen can be consumed by processes in a given solution.

Complete answer:
Biological oxygen demand and chemical oxygen demand differs from each other in the following ways:

Biochemical oxygen demand	Chemical oxygen demand
Aerobic organisms are crucial for BOD.	Organic solvents are used to execute COD.
BOD is determined by culturing a confined water sample for $5$ days at $20^\circ C$. The oxygen absorbed by aerobic organisms is determined by the reduction in oxygen concentration.	In a COD Experiment, a water sample is cultured for a predetermined amount of time and temperature with a powerful oxidizing agent in association with boiling sulphuric acid.
The BOD factor is obtained over a five-day period.	COD value can be assessed in a short period of time.
The value of BOD is lower than the COD value.	The COD number is always greater.
BOD is a phenomenon that is used to degrade natural organic substances and waste products in water.	The oxygen absorbed by acetates in the water sample is not quantified by COD.

Note:
The oxygen required by aerobic organisms to break down organic materials is measured by BOD. COD estimates the amount of oxygen consumed to chemically breakdown organic and inorganic materials in wastewater. Treated water can be categorized as weak, medium, strong, or extremely strong depending on the level of BOD and COD present.