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China has continuously promulgated standards for drinking water, sewage and industrial wastewater. Over the years, China has continuously promulgated drinking water, sewage and industrial wastewater standards, some of which have been revised several times. From the point of view of water disposal standards, drinking water disposal standards are the highest, followed by ultra-pure water treatment equipment for township sewage disposal, and finally industrial wastewater. Wastewater from various industrial occupations needs to reach certain discharge standards before it can be discharged, or it can be discharged into township sewage collection pipes for further disposal.

Water disposal needs to be very extensive. From the point of view of drinking water supply, most raw drinking water in China needs to be disposed of before reaching the standard of drinking water. The planned size COD of town sewage is between 400 mg/L-600 mg/L and BOD5 is more than 200 mg/L. If we want to reach the first standard of town sewage disposal in China, the removal rates of COD and BOD are over 80%, the removal rates of other total suspended matter are over 90%, the removal rates of total nitrogen are over 50%, the removal rates of ammonia nitrogen are over 70%, and the removal rates of total phosphorus are over 70%. The drop rate is over 80%. Because of the higher concentration of COD, BOD and other harmful substances in industrial wastewater, some occupations have reached tens of thousands, and the need for water disposal is also higher. It can be said that water disposal needs to exist widely in all aspects of industrial and agricultural days.

Water disposal skills evolve with water disposal needs promotion. Drinking water disposal is a super-pure water treatment equipment with good water quality and relatively simple disposal skills. The water quality needs to be met through several processes, such as mixing, reaction, deposition, filtration and disinfection. Because of the high concentration of harmful substances, sewage disposal skills are much more disorderly, usually divided into mechanical first-level disposal, biochemical second-level disposal and three-level deep disposal. In the meantime, mechanical primary disposal is the necessary skill for pre-disposal; biochemical secondary disposal further purifies water quality on the basis of primary disposal in order to reach the discharge standard, and more activated sludge process and its derivative skills are selected; and the third-level advanced disposal is mainly used in high-concentration sewage disposal with water resources, reclaimed water reuse or difficult management. Select membrane skills. It can be said that the evolution of water disposal skills is following the development of wastewater reduction, sewage disposal, reclaimed water reuse and water resources.