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Analysis for COD

Q. How to check raw water chemical oxygen demand? Tell me analytical process, sir.

dinesh kumar
engineer - Bhopal , madhyapradesh , India
April 2, 2016

Chemical Oxygen Demand

A. Hi Dinesh. Please review the relevant article in Wikipedia.
for an overview of the subject, and then obtain ISO 6060 which is the specific instructions for the analysis, and then get back to us with any questions. Good luck.

Regards,

Ted Mooney, P.E. RET
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
April 2016

A. DO must be field measured in-situ. Samples taken and sent to a lab will not yield the correct results.

Lyle Kirman
consultant - Cleveland Heights, Ohio
April 6, 2016

April 9, 2016

A. COD is measured in two ways: you can cook the wastewater up with a dichromate/sulfuric acid solution (plus a pinch of mercury), then determine the result via colorimetry; or, you can do it up in a similar solution, reflux, then back titrate the excess dichromate with sodium thiosulphate [on eBay or Amazon] or freshly standardized ferrous ammonium sulphate solution. The latter is more precise.

Dissolved oxygen is not the parameter being measured. One does that via Winkler titration (preferable) or electrode.

Dave Wichern
Consultant - The Bronx, New York

The COD can also be removed with a hook and line...
apologies, I couldn't resist.

Mark Lees
- fog encircled rock in the irish sea
June 23, 2016

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