Method for recycling high-salt waste water containing sodium chloride and sodium sulfate

Abstract

The invention discloses a method for recycling high-salt waste water containing sodium chloride and sodium sulfate, and belongs to the field of industrial waste water treatment. The method comprises the steps of filtering by a nanofiltration membrane, evaporating and crystallizing filtrate penetrating through the nanofiltration membrane to obtain sodium chloride, evaporating and crystallizing trapped fluid which cannot penetrate through the nanofiltration membrane to obtain sodium sulfate, returning a primary mother solution to the system, and mixing the primary mother solution with raw materials to be continuously recycled. By adopting the method, sodium sulfate and sodium chloride in the high-salt waste water can be effectively recycled, a purpose of treating the high-salt waste water can be realized, and the current environmental-protection demand can be satisfied, waste can be converted into treasure, the recycling of salts can be realized, and the benefit of factories can be increased.

Description

technical field [0001] The invention relates to a method for treating waste water, in particular to a method for recycling and treating high-salt waste water containing sodium chloride and sodium sulfate. Background technique [0002] A large amount of sewage is discharged during the coal chemical production process. In addition to organic matter, these sewage also contain a large amount of salt. Coal chemical wastewater is biochemically treated to reduce organic matter, and filtered to remove solid matter. The remaining wastewater mainly contains sodium sulfate, sodium sulfide, and trace amounts of other salts, which is usually called high-salt wastewater. [0003] The treatment technology of high-salt wastewater has been studied for decades at home and abroad, and the methods commonly used at present mainly include biological method, SBR process method and evaporation desalination method. Among the many high-salt wastewater treatment technologies, the evaporative desalin...

AI Technical Summary

Problems solved by technology

However, the solids precipitated by the evaporative desalination method are all mixed salts containing multiple salts at the same time. The purity is low and cannot be reused in industry. Usually, the mixed salts are discarded directly or handed over to hazardous waste treatment institutions for a fee of 300-1000 tons per ton. The price of 5,000 yuan is professionally treated, which not only increases the pressure on environmental protection, but also greatly increases the cost of wastewater treatment in the factory

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