Treating method for sewage containing sodium sulfate and sodium chloride

Abstract

The invention provides a treating method for sewage containing sodium sulfate and sodium chloride. The method comprises a step of preparing sewage to be treated as raw water and a step of carrying out nanofiltration on the raw water. The method may also comprise a step of carrying out evaporative crystallization on concentrated water obtained after nanofiltration so as to obtain anhydrous sodium sulfate. The method may further comprise a step of carrying out reverse osmosis treatment on yielded water obtained after nanofiltration and using yielded water obtained after reverse osmosis treatment as diluting water in nanofiltration of the raw water. The method may also comprise a step of carrying out secondary nanofiltration on yielded water obtained after nanofiltration so as to obtain concentrated water and yielded water obtained after secondary nanofiltration, a step of carrying out reverse osmosis treatment on yielded water obtained after secondary nanofiltration and carrying out evaporative crystallization on concentrated water obtained after reverse osmosis treatment so as to obtain sodium chloride, a step of using yielded water obtained after reverse osmosis treatment as diluting water in nanofiltration of the raw water, and a step of carrying out evaporative crystallization on concentrated water obtained after secondary nanofiltration in the sequence of concentration so as to obtain anhydrous sodium sulfate or subjecting the concentrated water together with next batch of raw water to nanofiltration again . The method provided in the invention can be used for separating and purifying anhydrous sodium sulfate and sodium chloride and for purifying sewage.

Description

technical field [0001] The invention relates to a sewage treatment method, in particular to a sewage treatment method containing sodium sulfate and sodium chloride. Background technique [0002] Sewage treatment is a process of purifying sewage to meet the water quality requirements for reuse. Industrial sewage contains high salinity, including sodium sulfate and sodium chloride. The presence of these salts hinders the removal of other impurities in sewage, which is not conducive to water purification. Among them, U.S. Patent No. 4,242,312, which was authorized and announced on December 30, 1980, discloses a method for removing sodium sulfate from a sodium chloride solution containing sulfate in a process for separating zirconium and hafnium. In this method, acetone, ethanol, A variety of organic reagents such as methanol, although sodium sulfate and sodium chloride are separated, and the purity of sodium sulfate reaches 99.9%, the organic reagents introduced not only have ...

AI Technical Summary

Problems solved by technology

Industrial sewage contains high salinity, including sodium sulfate and sodium chloride. The presence of these salts hinders the removal of other impurities in sewage, which is not conducive to water purification.

Among them, U.S. Patent No. 4,242,312, which was authorized and announced on December 30, 1980, discloses a method for removing sodium sulfate from a sodium chloride solution containing sulfate in a process for separating zirconium and hafnium. In this method, acetone, ethanol, Various organic reagents such as methanol, although sodium sulfate and sodium chloride are separated, and the purity of sodium sulfate reaches 99.9%, but the organic reagents introduced not only have an impact on the further purification of industrial sewage, but also pollute the environment

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