BOD is indirect measures of biodegradable organics in water. COD is indirect measures of total organic pollution in water. COD – BOD = Total non biodegradable organics. In this way, by measuring both BOD and COD we will get a clear picture of water pollution.
How can COD and BOD be used to assess water quality?
Like COD, biochemical oxygen demand (BOD) measurement can be used to estimate the amount of pollution in a water sample. COD describes the amount of oxygen required to chemically break down pollutants, while BOD indicates the amount of oxygen required to breakdown organic pollutants biologically with microorganisms.
How does BOD indicate water quality?
The dissolved oxygen readings are usually in parts per million (ppm). Higher BOD indicates more oxygen is required, which is less for oxygen-demanding species to feed on, and signifies lower water quality. Inversely, low BOD means less oxygen is being removed from water, so water is generally purer.
What is BOD and COD used for?
The Biochemical Oxygen Demand (BOD) and the Chemical Oxygen Demand (COD) tests are the main methods used in the determination of the concentration of organic matter in a sample of water.
How will you Analyse BOD and COD in polluted water?
BOD analysis is similar in function to chemical oxygen demand (COD) analysis, in that both measure the amount of organic compounds in water. However, COD analysis is less specific, since it measures everything that can be chemically oxidized, rather than just levels of biologically oxidized organic matter.
Can BOD and COD infer the quality of water?
Yes, both are important. BOD is indirect measures of biodegradable organics in water. COD is indirect measures of total organic pollution in water.
What is the purpose of COD?
COD is a measure of the oxygen equivalent of the organic matter in a water sample that is susceptible to oxidation by a strong chemical oxidant. COD is widely used as a measure of the susceptibility to oxidation of the organic and inorganic materials present in water bodies and in the municipal and industrial wastes.
How do you measure BOD and COD in water?
Testing for BOD involves incubating a sealed water sample at 20C for five days, followed by measuring the difference in oxygen content before and after incubation. COD measures how much DO is consumed by the oxidation of organic matter and inorganic compounds such as ammonia or nitrite under controlled conditions.
What is the relationship between the COD and BOD values in waste water?
The only relation between COD & BOD is – COD > BOD. For most industrial process waste water, community sewage, drains and even some hetrogeneous sources, COD/BOD ratio has been found to be in a defined range and hence, COD result gives more or less BOD value range for such identifiable waste water.
What is BOD test used for?
The test for biochemical oxygen demand (BOD) is a bioassay procedure that measures the oxygen consumed by bacteria from the decomposition of organic matter (Sawyer and McCarty, 1978). The change in DO concentration is measured over a given period of time in water samples at a specified temperature.
What is COD how COD is measured in polluted water state the significance of COD?
The chemical oxygen demand (COD) is a measure of water and wastewater quality. The COD test is often used to monitor water treatment plant efficiency. This test is based on the fact that a strong oxidizing agent, under acidic conditions, can fully oxidize almost any organic compound to carbon dioxide.
How COD is measured in polluted water?
COD Test. A COD test indirectly measures the concentration of organic compounds in a sample of water by measuring the amount of oxygen required for oxidation of all the organic compounds present. The common technique uses COD vials for measurement and results are typically achieved within 2 – 3 hours.
Why is COD analysis important?
COD analysis is used as an indirect measure of pollutants (organics) in a water sample. It is an important parameter in water quality analysis, helping to reduce risk to humans and the environment. COD is an excellent way of monitoring the efficiency of water treatment plants.
What are the two methods of determining the COD value of a water sample?
There are two methods available for COD determination namely open reflux and closed reflux.
Why is COD value higher than BOD value in polluted water?
COD is always higher than BOD because chemical oxidation is easier than biological oxidation.
Is there any correlation between COD and BOD?
COD typically correlates to BOD, which is one of the reasons the method was initially developed. It has been found to be a very useful tool in municipal wastewater treatment process monitoring and modeling, and to aid in process control.
What if COD is high in water?
When the COD levels are higher, there is a greater demand for oxygen. This means that there is likely more oxidizable organic material in water with high COD levels. This also means that there are reduced Dissolved Oxygen (DO) concentrations in wastewater with high COD levels.
What is the significance of the COD value of wastewater?
In wastewater treatment, the Chemical Oxygen Demand (COD) is an important measurement for the amount of oxygen that is required to break down pollutants (organic substances) in water. The chemical oxygen demand can be measured using different methods, direct or indirect.
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