Chemical Oxygen Demand of Water

The Chemical Oxygen Demand of Water (COD) in water test determines the oxidizable material with strong oxidizing agents.

COD increases as the concentration of organic material increases. It also increases if inorganic compounds susceptible to oxidation by the oxidant are present. Water with high COD typically contains high levels of decaying plant matter, human waste, or industrial effluent or combination of these.

The oxidant used in the determination oxidizes inorganic and organic compounds. The results can be expressed in terms of oxygen equivalent. However, H2S, Fe+2 and thiosulfate will also be measured by the COD test, along with the organic compounds.

Obviously, the results of the COD determinations may not correspond to the values of the BOD determinations, but may give some aid in estimating organic pollution loads. The COD of water will be higher than the BOD unless the water contains compounds not easily oxidized by chemical means but are biodegradable.

End of Chemical Oxygen Demand of Water

More about Dissolved Gases…
Total Organic Carbon in Water
Carbon Dioxide in Water

Next Topics…
Primary Nutrients in Water and Eutrophication
Toxic Constituents in Water
Pesticides in Water
Oil in Water

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