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What is the difference between bod and cod
BOD (Biochemical Oxygen Demand) and COD (Chemical Oxygen Demand) are two important parameters used to measure the organic strength of wastewater. Both BOD and COD are used to indicate the amount of organic matter in wastewater, but they measure different aspects of organic matter and have some differences:
Comparison | BOD (Biochemical Oxygen Demand) | COD (Chemical Oxygen Demand) |
Definition | Measures oxygen required by microorganisms to decompose organic matter over a certain period of time (usually 5 days) | Measures oxygen required to chemically oxidize all organic matter |
Test Method | Incubates a sample of water with microorganisms for a specific period of time and measures the amount of oxygen consumed | Oxidizes the organic matter in water with a strong oxidizing agent (such as potassium dichromate) and measures the amount of oxygen required |
Sensitivity | More sensitive to biodegradable organic matter, such as sewage | More sensitive to non-biodegradable organic matter, such as chemicals and pesticides |
Timeframe | Takes 5 days to measure | Can be completed in a matter of hours |
Table : Difference between BOD and COD .
Definition Of Bod And Cod:
BOD is a measure of the amount of oxygen required by microorganisms to break down the organic matter in wastewater over a specific period (usually five days) at a specific temperature (20°C). In contrast, COD is a measure of the amount of oxygen required to chemically oxidize the organic matter in wastewater.
Test Procedure:
The BOD test involves measuring the dissolved oxygen (DO) in a wastewater sample at the start of the test and again after five days of incubation under specific conditions. The difference between the initial and final DO values is used to calculate the BOD. In contrast, the COD test involves chemically oxidizing the organic matter in a wastewater sample using a strong oxidizing agent (usually potassium dichromate) and measuring the amount of oxygen consumed during the oxidation process.
Time and Accuracy:
BOD takes a longer time to complete (usually 5 days) compared to COD, which can be completed in a matter of hours. However, BOD is more accurate in measuring the organic strength of wastewater because it simulates the natural degradation process of organic matter in the environment, while COD measures all chemically oxidizable substances, including both biodegradable and non-biodegradable organic matter.
Applications:
BOD is widely used to assess the effectiveness of biological treatment processes, while COD is used as an indicator of the overall organic strength of wastewater, including the presence of toxic and refractory organic compounds.
In summary, BOD and COD are both useful measures of the organic strength of wastewater, but they measure different aspects of organic matter and are used for different purposes. BOD is more accurate but takes longer, while COD is faster but less specific.
Difference between BOD and cod . Difference between BOD and cod . Difference between BOD and cod .