COD Testing

COD Removal – Chemical Oxygen Demand

What is COD Removal in Wastewater?

COD or Chemical Oxygen Demand is the total measurement of all chemicals in the water that can be oxidized. TOC or Total Organic Carbon is the measurement of organic carbons.

How is COD measured?

COD TestingAt the GPC Clear solutions Laboratory, Our trained laboratory technicians test for Chemical Oxygen Demand using a spectrophotometer. The method involves using a strong oxidizing chemical, potassium dichromate Cr2O72-, to oxidize the organic matter in solution to carbon dioxide and water under acidic conditions. Often, the test also involves a silver compound to encourage oxidation of certain organic compounds and mercury to reduce the interference from oxidation of chloride ions. The sample is then digested for approximately 2 hours at 150°C. The amount of oxygen required is calculated from the quantity of chemical oxidant consumed.

Why is the reduction of COD important?

The reduction of Chemical Oxygen Demand is important because Higher COD levels mean a greater amount of oxidizable organic material in the sample, which will reduce dissolved oxygen (DO) levels. A reduction in DO can lead to anaerobic conditions, which is detrimental to higher aquatic life forms.

 Key Advantages of COD Removal

  • To keep your company’s trade effluent discharge in consent with the local water authorities MOGDEN formula.
  • Avoid breaching discharge consents resulting in heavy fines.
  • Reducing your company’s environmental impact.

How To Remove COD from Wastewater – The Solution

The use of GPC Clear Solutions coagulants and flocculants will remove most of the suspended solids from the effluent. All COD values associated with these solids will also be removed.

Any dissolved COD that is left will need to go forward for biological treatment.


COD Removal - Chemical Oxygen Demand 1



To learn more about Flocculation -> Visit Here

To learn more about Coagulation -> Visit Here




Removal of Suspended Solids and COD
You coagulate and flocculate effluent to remove the suspended solids from wastewater at the end of a manufacturing process. The coagulant changes the electrical charge of the suspended solids so they start to attract each other to form small particles. Flocculation brings these small particles together to form flocs, using mechanical processes (eg DAF) these flocs can be made to either rise or fall to allow them to be removed from the wastewater. Once these suspended solids and the COD values associated with them are removed, the clean effluent can then be let to sewer, potentially saving your company thousands of pounds annually in trade effluent charges.

Gpc Clear Solutions provide a FREE on-site assessment of your wastewater treatment requirements.

For more information on our products or to improve plant performance, fill in our enquiry form.

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