Method for separating sodium chloride and sodium sulfate in high-salinity wastewater in coastal industrial zone

Abstract

The invention discloses a method for separating sodium chloride and sodium sulfate in high-salinity wastewater in a coastal industrial zone. In the method, divalent salt and a part of organic mattersare separated from monovalent salt by utilizing characteristics of a nanofiltration membrane; thermal salt-sodium sulfate separation is performed to obtain sodium sulfate solid having high purity; a vibrating membrane is adopted as the nanofiltration membrane which has an advantage that the vibrating membrane can treat wastewater having extremely high salt concentrations; then a reverse osmosis system is adopted to effectively remove the monovalent salt, and sodium chloride solid having good purity is obtained after evaporative crystallization; nanofiltration is used for pretreatment of reverse osmosis, thus reducing the salinity of seawater entering a reverse osmosis membrane module, and creating conditions for improving the seawater desalination recovery rate. The method is reasonable inprocess, capable of recovering resources, economical, efficient, and stable to operate, can make up shortcomings of the existing high-salinity wastewater inorganic salt separating technology, and achieves the objective of 'zero emission of solid and liquid' for high-salinity concentrate treatment.

Description

technical field [0001] The invention relates to the technical field of inorganic salt separation in waste water, in particular to a method for separation of sodium chloride and sodium sulfate in high-salt waste water in coastal industrial belts. Background technique [0002] Nowadays, environmental issues are highly valued by human beings, and the effective utilization and treatment of high-salt wastewater has become the focus of more and more corporate projects. Some enterprises in the coastal industrial belt will produce a large amount of high-salt wastewater containing sodium chloride and sodium sulfate. At present, many enterprises are actively equipped with evaporation and crystallization devices to treat this kind of high-salt wastewater, but basically they obtain miscellaneous salts by direct evaporation and crystallization. As solid waste, even hazardous waste, further disposal is required. This will not only easily cause secondary pollution of the environment, but...

AI Technical Summary

Problems solved by technology

At present, many enterprises are actively equipped with evaporation and crystallization devices to treat this kind of high-salt wastewater, but basically they obtain miscellaneous salts directly by evaporation and crystallization. as solid waste, even hazardous waste, requiring further disposal

This will not only easily cause secondary pollution of the environment, but also cause high hazardous waste disposal costs to enterprises.

[0003] Based on this, Patent No. ZL201110461060.X announced a combined process based on nanofiltration membrane to treat sewage containing sodium sulfate and sodium chloride, but the raw water needs to be diluted with water, and the content of sodium chloride is higher than that of sodium sulfate, or The purity and yield of sodium chloride and sodium sulfate products obtained by using the published method for two kinds of high-salt wastewater with equivalent salt content will be limited

It can be seen that the prior art cannot guarantee high recovery rate and high purity for the inorganic salt content of high-salt wastewater.

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