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BOD Full Form: Introduction, Measurement, Significance

The quantity of oxygen needed by aerobic microbes to decompose organic matter in water is known as the biochemical oxygen demand (BOD). It gauges how well the water can support aquatic life.

BOD is calculated as mg/L, or micrograms of oxygen per liter of water. More organic matter is present in the water’s surface and less oxygen is accessible for aquatic life the higher the BOD.

BOD is a significant indicator of water quality. It is used to evaluate the efficacy of wastewater treatment plants and to pinpoint pollutant sources.

There are two types of BOD: five-day BOD (BOD5) and 20-day BOD (BOD20). BOD5 is the more common type of BOD and is used to assess the immediate impact of pollution. BOD20 is used to assess the long-term impact of pollution.

Introduction to BOD

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BOD means “biochemical oxygen demand.” This phrase refers to the quantity of oxygen needed to decompose organic material in water. The amount of pollution in the water rises as the BOD level increases. As a result, it serves as a crucial water quality indicator.

BOD concentrations are frequently expressed in milligrams per litre (mg/L). Standards for permissible BOD levels in various kinds of water have been set by the Environmental Protection Agency.

Importance of BOD

The importance of BOD can be summarized as follows:

  • BOD is a measure of the amount of organic matter in water.
  • High BOD levels indicate that the water is polluted and may not be suitable for supporting aquatic life.
  • BOD can be reduced by a number of methods, including aeration, bioremediation, and physical treatment.
  • BOD monitoring is an important part of ensuring that water quality standards are met.
Bod Oxygen Bacteria Diagram Jpg

Effects Of High BOD Levels

High BOD levels can have a number of negative effects on aquatic ecosystems. These effects can include:

  • Decreased dissolved oxygen levels: The microbes require oxygen as they decompose the organic waste. This may result in lower water oxygen concentrations, which might be detrimental to aquatic life.
  • Increased nutrient levels: Additionally, nutrients like nitrogen and phosphorus can be released into the water as a result of the decomposition of organic waste. These nutrients may help algae and other aquatic plants prosper, which could further decrease dissolved oxygen levels and upset the ecosystem’s a state of equilibrium
  • Pollution: High BOD levels may also be a sign of water that is contaminated. There are multiple possible explanations for this, including sewage, industrial waste, and agricultural runoff. Aquatic life may be harmed by pollution, which also renders water unfit for human consumption.
  • Disease: Additionally, high BOD levels can foster an environment that is conducive to the development of harmful bacteria and other microbes. When people and animals come into touch with the water, these microbes may infect them with illnesses.

How Can BOD Levels Be Reduced?


Here are some ways to reduce BOD levels in water:

  • Aeration: The process of aerating water involves including oxygen. Air bubbles in the water or the use of mechanical aerators may achieve this. Aeration helps raise the water’s dissolved oxygen levels, which can lower BOD concentrations.
  • Bioremediation: The process of bioremediation involves using microorganisms to break down organic materials. Putting bacteria or additional microbes to the water will do this. If done correctly, bioremediation can be a time- and money-saving method of lowering BOD levels.
  • Physical treatment: Reducing pollution at the source is the most effective strategy to lower BOD levels. This can be achieved by managing wastewater treatment facilities, minimizing agricultural runoff, and regulating pollutants from industry.
  • Reduce pollution: Getting rid of pollution at the source is the greatest strategy to lower BOD levels. Controlling industrial pollutants, lowering runoff from agriculture, and managing wastewater treatment facilities can all help with this.

Benefits of Reducing BOD

Improved water qualityReduced BOD levels lead to cleaner water, which can support aquatic life and recreation.
Reduced risk of waterborne diseasesWhen BOD levels are low, there is less food available for bacteria and other microorganisms that can cause waterborne diseases.
Increased efficiency of wastewater treatment plantsReducing BOD levels can help wastewater treatment plants operate more efficiently and reduce their operating costs.
Protection of aquatic ecosystemsReduced BOD levels can help protect aquatic ecosystems by reducing the amount of pollution that enters rivers, lakes, and oceans.
Improved public healthReduced BOD levels can help improve public health by reducing the risk of waterborne diseases.


BOD stands for biochemical oxygen demand. It is a measure of the amount of oxygen that is required to break down the organic matter in water. BOD is expressed in milligrams of oxygen per liter of water (mg/L).
BOD is measured in a laboratory using a BOD test. The test involves collecting a sample of water and incubating it in a controlled environment for a period of time, typically five days. During this time, the microorganisms in the water break down the organic matter, using up oxygen. The amount of oxygen used is measured at the end of the incubation period.

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