Zero-emission sewage reutilization device and method

Abstract

The invention relates to the technical field of zero-emission sewage reutilization and provides a zero-emission sewage reutilization device. A zero-emission sewage reutilization method sequentially comprises steps as follows: miscellaneous salt is subjected to coagulative sedimentation, sodium carbonate is added and calcium carbonate precipitates are obtained; caustic soda is added, and magnesium hydroxide is obtained; membrane filtration is performed, the pH value is regulated, ion exchange softening, advanced oxidation, biochemical treatment with a biological membrane are performed, filtration with a membrane filter and nanofiltration are performed, lime milk is added to interception water obtained through nanofiltration, calcium sulfate is obtained, a supernatant flows back to a miscellaneous salt sedimentation basin, nanofiltration permeate water is concentrated through a reverse osmosis separator A and then is concentrated by a brine concentrator, fresh water produced by the brine concentrator is concentrated by a reverse osmosis concentrator B and flows back to the brine concentrator, concentrated water produced by the brine concentrator enters an crystallizing evaporator and is subjected to hot separation and cold separation, sodium chloride and sodium nitrate are obtained respectively, most crystallization mother liquor is subjected to refluxing treatment, and a small part of crystallization mother liquor is dried; reverse osmosis produced water and distilled water are reused. According to the invention, commercial calcium carbonate, magnesium hydroxide, calcium sulfate, sodium chloride, sodium nitrate salts and high-quality reused water are recycled, emission of solid waste is small, and the operating cost is low.

Description

Technical field [0001] The invention relates to the technical field of sewage treatment, and relates to a liquid zero discharge method for obtaining reclaimed water by treating sewage and separating the crystals of main salts in the water. Background technique [0002] With the intensification of human economic activities, water resources will surely become the bottleneck of economic development. Therefore, in more and more cases, it is necessary to regenerate sewage into reclaimed water that can replace raw water; in some cases, it is necessary to achieve zero liquid discharge. [0003] The common reclaimed water technology is to process the sewage after the traditional biochemical treatment or other sewage with low organic pollution, including flocculation sedimentation, ultrafiltration, and reverse osmosis. The current main problem is that the organic pollutants are not treated deeply before entering the membrane system. Pollutants are still at a high level, reverse osmosis cle...

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Problems solved by technology

[0007] The present invention solves the technical problem of frequent reverse osmosis cleaning in reclaimed water technology, and the reverse osmosis concentrated water cannot meet the discharge standard; the reverse osmosis membrane needs frequent chemical cleaning in the liquid zero discharge sewage treatment method, and the operation of concentrated water evaporation crystallization is difficult, and the obtained evaporation crystallization is A large amount of mixture of miscellaneous salts and organic pollutants, the whole system is difficult to run stably for a long time, the proportion of salt recovery is low, the amount of chemical sludge is large, and the problem of high operating costs

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