5 Simple Techniques For chemical oxygen demand test
5 Simple Techniques For chemical oxygen demand test
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The dedication of wastewater quality set forth in environmental permits is proven Considering that the seventies inside of a number of laboratory tests centered on 4 key categories:
The change in DO focus in excess of 5 days represents the "oxygen demand" for respiration by the aerobic Organic microorganisms inside the sample.
The COD test should be thought of an independent evaluate with the natural make a difference inside a wastewater sample rather than a substitute with the BOD test.
The COD test is often a handy measure of effluent excellent of the wastewater treatment plant. It offers a quick, approximate evaluate of all chemically oxidizable substances and can be utilized to establish effectiveness complications in procedure services.
Do có nồng độ cao trong phần lớn các loại nước thải nên chloride thông thường là nguồn quan trọng nhất trong việc gây nhiễu. Phản ứng của nó với dicromat kali như sau:
Nhiều chính quyền đưa ra các quy định chặt chẽ liên quan tới nhu cầu oxy hóa học tối đa được phép trong nước thải trước khi nó được đưa trở lại môi trường.
Digest your samples in addition to a reagent blank. (The reagent blank is just a sample of deionized h2o that’s handled similar to your genuine samples. You can even reuse the blank for as long as your reagent batch lasts.)
Alternatively, the absorbance of hexavalent chromium at 420 nm can be utilized to determine the amount of extra chromium at the end of digestion to find out COD values.
Shake the flask vigorously to dissolve the contents, then insert a thousand ml of h2o and Mix totally.
The measurement of COD is usually performed by incorporating a robust oxidising agent, like potassium dichromate, to some sample under acidic disorders and heated for two hrs. The amount of dichromate left presents an indication of the amount here of natural make any difference was existing.
A COD reactor/heating (a hundred and fifty°C) block along with a colorimeter are turned on in order that both instruments are permitted to stabilize.
Conductivity Measurement: Conductivity measurement relies on the power of h2o to perform electrical present-day mainly because of the existence of ions.
Both equally solutions for COD testing need the digestion stage, so a heating block on your samples is very important for making certain precise and repeatable effects. For most effective success, look for a heating block that attributes numerous temperatures, so you've got utility for other tests, including whole phosphorus.
Knowledge the principle of COD is essential for Those people involved in environmental science, check here civil engineering, and wastewater treatment.