The Difference Between COD and BOD – An Explanation for Environmental Enthusiasts
When it comes to assessing the health of water bodies, two terms commonly come up – COD and BOD. These are acronyms that describe specific parameters used by environmental scientists to measure the level of pollutants in water resources. While COD and BOD are similar in terms of their purpose, they are different in their scope and measurement methods. In this article, we will explore the difference between the two terms and how they affect our water resources.
COD – Chemical Oxygen Demand
COD or Chemical Oxygen Demand is a measure of the total amount of oxygen required to oxidize all the organic and inorganic components present in water. Simply put, it measures the amount of organic and inorganic chemicals in the water that require oxygen to break down. The unit of measurement for COD is milligrams per liter (mg/L).
COD is important in assessing industrial wastewater treatment plants’ efficiency in removing pollutants from wastewater. This is because COD is a quick measurement and can provide insight into the general levels of pollutants present in industrial effluent. While COD doesn’t provide information on the specific types of pollutants present, it is useful in identifying the overall level of contamination.
BOD – Biochemical Oxygen Demand
In contrast, BOD or Biochemical Oxygen Demand, measures the amount of oxygen required to break down only the organic pollutants present in water. The measurement is taken by measuring the oxygen used by bacteria to break down organic matter over a specific time period, typically five days. The unit of measurement for BOD is also milligrams per liter (mg/L).
BOD measurement is often used to assess the health of natural water ecosystems, such as rivers and lakes. This is because it provides a more specific measure of organic pollution present that can be harmful to fish and other aquatic life. It also takes into consideration the effects of temperature, pH, and other environmental factors on the breakdown of organic matter.
Difference Between COD and BOD
While COD and BOD have different measurement methods and scope, they both serve the purpose of measuring the level of pollutants present in water resources. COD measures both organic and inorganic pollutants, while BOD only measures organic pollutants. COD is a quicker measurement and doesn’t take into consideration the environmental factors that may affect the degradation of organic matter. BOD, on the other hand, provides a more specific measure of organic pollution present that can be harmful to aquatic life.
In conclusion, COD and BOD are both crucial measurements in assessing and maintaining water quality. While they have different methods and scopes, they are complementary to each other in providing insight into the level of contamination in water resources. With proper monitoring, management, and regulation, we can safeguard our water resources and ensure the health and well-being of our ecosystems.
Table difference between cod and bod
| COD | BOD |
| — | — |
| Chemical Oxygen Demand | Biochemical Oxygen Demand |
| Measures the amount of oxygen required to chemically break down organic matter in water | Measures the amount of oxygen required by bacteria to decompose organic matter in water |
| Results can be obtained within hours | Results can take 5-7 days |
| Provides an indication of the overall organic pollution levels in water | Provides an indication of the amount of biodegradable organic matter in water |
| Can measure both biodegradable and non-biodegradable organic matter | Can only measure biodegradable organic matter |
| Can be influenced by inorganic substances in the water | Only influenced by the presence of biodegradable organic matter |
| Widely used in industries and municipal wastewater treatment plants to monitor and control water quality | Mostly used in environmental monitoring and research studies |