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"Analysis for COD"

April 2, 2016

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

dinesh kumar
engineer - Bhopal , madhyapradesh , India

Chemical Oxygen Demand
April 2016

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


pic of Ted Mooney
Ted Mooney, P.E. RET
Aloha -- an idea worth spreading
finishing.com - Pine Beach, New Jersey

April 6, 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 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 backtitrate the excess dichromate with thiosulfate or freshly standardized ferrous ammonium sulfate 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
Dave Wichern
Consultant - The Bronx, New York

June 23, 2016

thumbs up sign 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

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