When it comes to water quality testing, the requirements of each monitoring point are guaranteed. It is necessary to configure water quality testing instruments to measure the physical and chemical indicators of water quality. So, what are the common online water quality detectors? In this chapter, Modi-Tech will introduce some monitoring equipment for conventional sewage to everyone.
The general conventional sewage detection equipment includes: total nitrogen online analyzer, COD online analyzer, total phosphorus online analyzer, multi-parameter water quality online analyzer, ammonia nitrogen online monitor, permanganate index online analyzer, total phosphorus and total nitrogen online monitor, water quality color online monitor, etc.
The TN-8000 total nitrogen online analyzer uses the ultraviolet colorimetric method. Under high temperature and high pressure conditions, both the potassium persulfate oxidant and the water sample are oxidized and digested by potassium persulfate, and the nitrogen-containing compounds in the water sample are transformed into nitrates. Then adjust the acidity or alkalinity of the solution. When the depth of the solution’s color under ultraviolet light is directly proportional to the total nitrogen content in the water sample, measure the absorbance value of the reactants. In this way, the total nitrogen content can be determined.
Hangzhou Moody produces two types of COD online analyzers with different detection methods: one is the ultraviolet method, and the other is potassium dichromate high-temperature digestion and colorimetric determination. Which specific method is needed, of course, depends on the specific requirements of the customer.
The basic measurement principle of the ultraviolet colorimetric instrument is based on the absorption of ultraviolet rays by organic matter in sewage. Organic substances containing conjugated double bonds or polycyclic aromatic hydrocarbons have an absorbing effect on ultraviolet light when dissolved in water. Therefore, by measuring the degree to which these organic substances absorb ultraviolet light, we can assess the extent to which the water body is polluted by these organic substances. The application fields include drinking water, surface water, industrial process water, sewage treatment and other areas. It can be used for continuous monitoring of the degree of organic pollution in raw water, the inlet of sewage treatment plants, the removal rate of organic matter during the treatment process, as well as the degree of organic pollution in industrial circulating water, etc.
2) High-temperature digestion of potassium dichromate and colorimetric determination; The Cr (VI) in the mixed solution formed by water sample, potassium dichromate, silver sulfate (as a catalyst to oxidize linear aliphatic compounds more fully) and concentrated sulfuric acid is reduced to Cr (III) under high temperature and high pressure conditions, thereby changing the color of the mixed solution. The degree of color change of the solution corresponds to the concentration of COD (Chemical Oxygen Demand) of the water sample being measured. The instrument can directly determine the COD value of the water sample through photoelectric colorimetry. In addition, chloride ions in the water sample are the main interfering substances. This instrument can eliminate the interference of chlorine by adding mercuric chloride to complex the chloride ions in the water sample.
The above is a brief introduction to the working principle of the total nitrogen and COD detection instruments produced by Hangzhou Modi. If you want to know more about other instruments for conventional sewage monitoring, you can follow the Hangzhou Modi website!
