chemical oxygen demand test Secrets
chemical oxygen demand test Secrets
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Prepare the reagent blank by eradicating the COD vial cap and pipetting deionized h2o in lieu of sample to the vial.
The “cod” symbol will flash for three seconds, then the sample test result will appear during the Screen as element for every million COD. Record the test final result.
As a result, COD tests give a far more correct estimate of the full volume of natural and organic compounds in h2o.
The COD test is usually a handy measure of effluent high quality of the wastewater therapy plant. It provides A fast, approximate evaluate of all chemically oxidizable substances and can be utilized to determine performance challenges in treatment method services.
The dichromate oxidizes the organic subject in the sample, and the excess dichromate is then titrated by using a lessening agent to ascertain the level of dichromate that was consumed.
Over the digestion, It is necessary to own excess oxidant as this makes sure finish oxidation with the sample. Consequently, it’s essential to decide the amount of excess oxidant. The two most typical procedures for this are titration and colorimetry.
During the existence of a strong oxidising agent in an acidic setting, virtually any organic component will oxidise to carbon dioxide, based on the COD testing process.
One more problem is the inability of the traditional COD methods to differentiate involving biologically obtainable and inert natural and organic matter. This may result in overestimation of the quantity of oxygen demanded read more for Organic treatment method procedures.
The COD test utilizes a chemical (potassium dichromate inside a fifty% sulfuric acid Option) that “oxidizes” both natural and organic (predominate) and inorganic substances in a very wastewater sample, which ends up in a higher COD concentration than BOD focus for the same wastewater sample because only natural and organic compounds are consumed during BOD testing.
This glossary article aims to deliver an in-depth idea of Chemical Oxygen Demand, its importance in wastewater cure, as well as approaches used for its determination.
It consists of the oxidation of natural and organic and inorganic carbon compounds current in the click here h2o sample at significant temperatures.
Chloride is the main interference when testing for COD. Each COD vial utilised Using the dichromate system consists of mercuric sulfate that could eliminate chloride interference approximately the extent laid out in the procedure.
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Along with the potassium dichromate in fifty% sulfuric acid Remedy, pre-prepared COD vials also consist of silver sulfate like a catalyst and mercuric sulfate to eliminate chloride interference. Consequently, COD vials are deemed harmful squander and should be managed and disposed of within an accepted fashion.