COD Removal – Chemical Oxygen Demand

What is COD 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? At 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...
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