Chemical Oxygen Demand of Water
The chemical oxygen demand test determines the oxidizable material with strong oxidizing agents.
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, something like acetate or phenols.