The significance of COD analyzer

The reducing substances in water include various organic substances, nitrites, sulfides, ferrous salts, etc. But the main thing is organics. Therefore, chemical oxygen demand (COD) is often used as an indicator to measure the amount of organic matter in water. The greater the chemical oxygen demand, the more serious the water pollution by organic matter. The determination of chemical oxygen demand (COD) varies with the determination of reducing substances in water samples and the different determination methods.

At present, the most commonly used are the acid potassium permanganate oxidation method and the potassium dichromate oxidation method. Potassium permanganate (K2MnO4) method has a low oxidation rate, but is relatively simple, and can be used when determining the relative comparative value of organic matter content in water samples. Water containing a large amount of organic matter will contaminate the ion exchange resin when it passes through the desalination system, especially the anion exchange resin, which reduces the exchange capacity of the resin. When organic matter is pretreated (coagulation, clarification and filtration), it can be reduced by about 50%, but it cannot be removed in the desalination system, so it is often brought into the boiler through make-up water to reduce the pH value of the boiler water. Sometimes organics can also be brought into the steam system and condensate, lowering the pH and causing system corrosion. High levels of organic matter in circulating water systems can promote microbial reproduction.