COD testing Secrets
COD testing Secrets
Blog Article
Biological Oxygen Demand (BOD) The amount of oxygen, taken up with the microorganisms that decompose the organic and natural squander issue in wastewater is recognized as biological oxygen demand or biochemical oxygen demand.
This oxidation is catalyzed by silver sulfate. The catalyst is needed, Specifically to oxidize low molecular body weight fatty acids. The oxidation from the acidified dichromate is often represented by the next equation:
Inspite of some troubles, COD continues to be a beneficial tool for monitoring and managing the cure procedures in the wastewater procedure plant and guaranteeing compliance with environmental restrictions.
WARNING! Given that O&G adheres to plastic, only glass sample collection containers can be employed to collect O&G samples!
At this time, most COD tests use potassium dichromate because the oxidant. Potassium dichromate can be a hexavalent chromium salt that's brilliant orange in coloration and may be very solid.
Various warmth and oxygen, ultraviolet radiation and chemical oxidant-based mostly methods can be found to measure TOC that are precise to the carbon examining instrument used.
The images or other third party product in the following paragraphs are A part of the post's Creative Commons licence, Except indicated usually inside a credit line to the fabric. If product just isn't A part of the short article's Imaginative Commons licence plus your meant use is not really permitted by statutory regulation or exceeds the permitted use, you will have to get authorization straight from the copyright holder. To see a copy of this licence, visit .
Note the distinction concerning this and the other oxygen demand test (BOD). COD is when all components are totally chemically oxidized; BOD is only that substance which happens to be oxidized by (sometimes uncooperative) germs over a period of five times. Any approach that is certainly capable of oxidizing compounds and makes it possible for the level of oxidation to generally be calculated could theoretically be applied to determine COD. The dichromate ion (Cr2O72-) has tested by itself for being greatest suited to common function COD and is required in all accredited techniques.
The h2o sample is boiled get more info with potassium dichromate within a strongly acidic medium underneath reflux. The natural and organic compounds current in the sample are oxidized through the dichromate.
The vital point is the fact that once you have founded a mean COD:BOD ratio to your wastewater stream, then the comparatively simple and brief COD test may be used to predict BOD with relative reliability.
COD describes the level of oxygen required to chemically break down pollutants, even though BOD indicates the amount of oxygen necessary to break down organic and natural pollutants biologically with microorganisms.
Pipet two milliliters of sample into Just about every vial. Be aware that adding the sample will induce an exothermic reaction plus the vial will develop into sizzling.
Which of our measuring devices is greatest fitted to the expense- and benefit-optimized Answer for your measuring task?
Combined with the potassium dichromate in 50% sulfuric acid solution, pre-prepared COD vials also incorporate silver sulfate as a catalyst and mercuric sulfate to eliminate chloride interference. Therefore, COD vials are regarded as dangerous waste and have to be handled and disposed of get more info in an approved fashion.