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Guilherme Mazui

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What is the Difference Between BOD and COD?

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The main difference between Biochemical Oxygen Demand (BOD) and Chemical Oxygen Demand (COD) lies in the processes used to measure the oxygen required to break down organic materials in water. Here are the key differences between BOD and COD:

  • Process: BOD is a biological oxidation process performed by aerobic organisms, while COD is a chemical oxidation process performed by chemical reagents.
  • Measurement: BOD is measured by keeping a sealed water sample for incubation for a period of 5 days at 20 degrees Celsius, whereas COD can be measured within a few days.
  • Value: COD is always greater than BOD because chemical oxidation is easier than biological oxidation. A good BOD level is an expected value of 1-2 ppm.
  • Purpose: BOD is used to oxidize natural organic matter and organic waste in water, while COD is used to measure the oxygen-demanding strength of wastewaters.

In summary, BOD measures the amount of oxygen required by aerobic organisms to decompose organic matter, while COD measures the amount of oxygen required to break down organic material via chemical oxidation. COD is always higher than BOD, and both parameters are used to assess the oxygen-demanding strength of wastewaters.

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  • What is the Difference Between BOD and COD?
  • Comparative Table: BOD vs COD

    • Comparative Table: BOD vs COD

    The main differences between Biochemical Oxygen Demand (BOD) and Chemical Oxygen Demand (COD) are presented in the following table:

    Parameter BOD COD
    Definition BOD measures the amount of oxygen required by aerobic microorganisms to break down organic matter in water. COD measures the total amount of oxygen needed for chemical oxidation to break down organic materials in water.
    Oxidation Process Biological oxidation process. Chemical oxidation process.
    Method BOD is determined by incubating a sealed water sample for 5 days at 20 degrees Celsius. COD is determined by incubating a water sample with a strong oxidant in combination with boiling sulfuric acid for a specific period of time and temperature.
    Time Taken for Determination BOD value is determined in 5 days. COD is estimated within a few days.
    Values of Measurement BOD value is lesser than COD. COD value is always greater than BOD.
    Test Procedure Aerobic microorganisms are used to oxidize the natural organic matter and organic waste in the water. COD utilizes a strong oxidizing reagent to oxidize materials in water.
    Complete Breakdown of Pollutants In BOD, a complete breakdown of pollutants does not occur. In COD, a complete breakdown of pollutants takes place.

    BOD and COD are both parameters used to measure water quality and the amount of organic pollution in water. BOD focuses on the amount of oxygen used by aerobic microorganisms to break down organic matter, while COD measures the amount of oxygen needed to oxidize all organic and inorganic pollutants in water chemically.

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    Guilherme Mazui

    Guilherme Mazui is graduated in journalism from the Federal University of Minas Gerais (UFMG) and a master's degree in Communication from the University of São Paulo (USP). In addition, he has experience in advertising writing and has worked as a content editor in several companies.