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printech, December, 2001
Re: C.O.D.


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From: Gary Jones (gjonesprinting@aol.com )
Date: Mon, 3 Dec 2001 15:19:22


COD is an acronym that stands for Chemical Oxygen Demand. COD is used in the waste water discharge area and represents both a specific technique for measuring the amount of oxygen required to oxidize all compounds, both organic and inorganic, in water as well as a discharge limit. 

Oxygen demand is important with waterways that receive discharges from business, industry, and homes as the need to preserve the dissolved oxygen balance is critical to the long term survival of aquatic ecosystems. Unless sufficiently treated, materials that have a high COD level will cause a depletion in available oxygen in the waterway which can cause all of the living things depending upon that dissolved oxygen such as fish, bacteria, etc., to die. 

COD is measured by titrating a sample of the wastewater so that all of the organic and most inorganic materials are converted to carbon dioxide and water with strong oxidizing agents, under acidic conditions. The COD test is generally more reproducible than the BOD (Biological Oxygen Demand) test, and will result in a higher number than the BOD test. The BOD and COD results do not necessarily correlate as they do not measure the same materials in the wastewater.



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