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How much is the BOD water quality tester (what does BOD mean in water quality)

by:BOQU     2022-07-31

Generally, people who are new to the sewage industry often hear several indicators in the discharge standard: BOD, COD, TP, TN, and SS. The latter three are easy to understand, total phosphorus, total nitrogen and suspended solids. But BOD and COD, one is Biochemical Oxygen Demand and the other is Chemical Oxygen Demand. These two are dizzy just by looking at their names. Friends who have just entered the business may not be able to tell them apart. In fact, these two oxygen demands represent is the content of organic matter in wastewater. So why use BOD and COD as pollutant indicators?

Most of the pollutants in sewage are organic matter, but there may be dozens of kinds of organic matter in wastewater, and there may be hundreds or even thousands of kinds. It is impossible for us to take every organic matter out as an indicator of effluent. At this time, we need a unified indicator to represent the organic matter in wastewater. We know that organic matter is composed of hydrocarbons, which can be oxidized by strong oxidants, or oxidatively decomposed by microorganisms, and the products are carbon dioxide and water. Oxygen will be consumed in the process of oxidation. The more oxygen consumption, the more organic matter in the wastewater. Therefore, chemical oxygen demand and biochemical oxygen demand, that is, COD and BOD, are used to represent the organic matter content in the wastewater.

So what exactly does BOD mean? BOD refers to the content of dissolved oxygen required by microorganisms to decompose organic matter. In the actual measurement of dissolved oxygen consumption in water, a period of 5 days is generally used, which is called BOD5. COD refers to the determination of the amount of oxidant consumed by reducing substances in a unit volume of water sample under certain conditions. Generally, the potassium dichromate method is used, which is called coder. The higher the BOD and COD values, the more serious the water pollution.

Organic matter in wastewater is divided into degradable organic matter and non-degradable organic matter. Microbes can only use degradable organic matter, while strong oxidants can oxidize all organic matter, so BOD means degradable organic matter, and COD means all organic matter. The difference between these two data indicates that the COD must be greater than the BOD of the non-degradable organic matter without measurement errors. Usually, the value of BOD/COD can be used to roughly represent the biodegradability of wastewater. Generally, when it is greater than 0.3, the wastewater is considered to be biodegradable. The larger the ratio of the two, the higher the biodegradability of wastewater.

Water quality COD detectors are relatively common, whether it is price or detection principle, everyone knows more, but little is known about BOD water quality detectors. Most of the BOD water quality analyzers on the market use a simple, safe and reliable mercury-free differential pressure sensing method to measure BOD in water.

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