Explain the difference between ThOD, COD, and BOD in relation to sewage
ThOD (Theoretical Oxygen Demand), COD (Chemical Oxygen Demand), and BOD (Biochemical Oxygen Demand) are all parameters used to measure the amount of oxygen required to break down organic matter in a sample of water, such as sewage.
ThOD refers to the amount of oxygen required to completely oxidize all organic and inorganic substances present in a sample of water. It is calculated theoretically based on the chemical composition of the sample.
COD is a measure of the amount of oxygen required to chemically oxidize organic and inorganic substances in a sample of water. It is often used as an indicator of the overall pollution level in water, as it represents both biodegradable and non-biodegradable organic matter.
BOD is a measure of the amount of oxygen required by microorganisms to break down organic matter in a sample of water. It is a key indicator of the level of biodegradable organic pollutants in water, as it represents the oxygen demand of microorganisms during the decomposition process.
In relation to sewage, ThOD provides an estimate of the total oxygen demand of the wastewater, while COD gives a measure of the overall pollution level, and BOD specifically indicates the biodegradable organic pollutants present in the sewage that can be decomposed by microorganisms.