Process and equipment for separating salt and nitrate without industrial wastewater discharge

Abstract

The invention discloses a process for separating salt and nitrate without industrial wastewater discharge. The process includes evaporating and concentrating sodium sulfate in high-temperature states until the sodium sulfate is in near saturation states; crystallizing out mirabilite under low-temperature freezing conditions; evaporating and crystallizing out sodium chloride under high-temperature conditions; carrying out hot melting on the mirabilite and crystallizing and dehydrating the mirabilite to dissolve out the sodium sulfate. The invention further discloses equipment for implementing the process. The process and the equipment have the advantages that the sodium sulfate and the sodium chloride in industrial wastewater with the salt and the nitrate can be separated and recycled, accordingly, the wastewater is free of impurity salt, the impurity contents can be reduced, the process and the equipment are free of discharge substances which can cause pollution of water systems, and technical effects of recycling resources without pollution liquid discharge can be realized; the process is low in energy consumption, the treated wastewater can be recycled, and the process and the equipment are suitable for industrially treating the wastewater; industrial-grade sodium sulfate and sodium chloride products further can be obtained, and the solid waste or hazardous waste production probability can be lowered; the equipment is high in heat efficiency and automation degree and low in power consumption and operation cost, and sustainable development requirements can be met by the equipment.

Description

technical field [0001] The invention belongs to the technical field of sewage treatment, and in particular relates to a treatment process and equipment for industrial waste water, in particular to a salt and nitrate separation process and equipment for zero discharge of industrial waste water. Background technique [0002] In recent years, environmental and energy issues have become the most prominent issues affecting the long-term stable development of the country and enterprises. With the rapid development of industry, the types and quantities of wastewater have increased rapidly, and the pollution of water bodies has become increasingly widespread and serious, threatening human health and safety. The hazards of industrial wastewater are mainly: heavy metals and other difficult-to-degrade toxic and harmful substances are continuously enriched as sewage enters the soil, resulting in excessive heavy metals in farmland and endangering food safety; sludge from sewage treatment...

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Problems solved by technology

[0003] In the process of zero discharge of industrial wastewater in salt chemical industry, chlor-alkali chemical industry, coal chemical industry, wet smelting, pharmaceutical and other industries, the wastewater contains sodium chloride and sodium sulfate components at the same time. If this wastewater directly enters the evaporation crystallization system The generation of mixed salt will not only not be able to be used as resources, but will generate a large amount of solid waste, which must be disposed of qualitatively as hazardous waste, resulting in high processing costs and poor economic efficiency. This high cost will seriously affect the project progress of the enterprise, and at the same time , using the above-mentioned traditional treatment method, because the crystalline salt in this kind of wastewater is miscellaneous salt, the impurity content is high, the product cannot be reused, it is difficult to recycle, and there is still waste liquid discharge and high energy consumption

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