Process for treating sodium sulfate wastewater by using nanofiltration-reverse osmosis combined membrane

Abstract

The present invention relates to a process for treating sodium sulfate wastewater by using a nanofiltration-reverse osmosis combined membrane. According to the process, the pretreated sodium sulfate wastewater is conveyed to a nanofiltration membrane stack through a high pressure pump, and the nanofiltered concentrated solution is subjected to multiple effect evaporation crystallization to obtain an anhydrous sodium sulfate product and condensed water, wherein the condensed water is recycled; the nanofiltered producing water is conveyed to a reverse osmosis membrane stack through the high pressure pump, the resulting concentrated solution returns to the pretreated sodium sulfate stock solution to carry out the secondary nanofiltration, and the reverse osmosis producing water is recycled, wherein the concentrated solution is subjected to the reverse osmosis membrane stack. Compared to other pollution control technologies, the process of the present invention has the following advantages that: the equipment is compact, and the land occupation is small; no morphological and chemical influence is generated to the treated object; the process is a continuous process, and the automatic and uninterrupted operating can be achieved; the process has characteristics of low energy consumption, no phase change, no temperature change, easy control and simple operation; the process can be directly circulated on the site; the sodium sulfate is subjected to concentration, evaporation crystallization, and recovery utilization in the absence of chemical and physical changes, such that the zero discharge of the sodium sulfate wastewater is achieved; the reverse osmosis producing water is adopted as the process pure water to use so as to save a large amount of the process water.

Description

Technical field: [0001] The invention relates to a sewage treatment method, in particular to a treatment method for treating sodium sulfate wastewater produced in metallurgy, chemical industry and other fields by using membrane technology, comprehensively recovering sodium sulfate, and reusing produced water. Background technique: [0002] In the production process of metallurgical and chemical enterprises, due to the enrichment of ions caused by acid-base neutralization, a large amount of wastewater containing sodium sulfate is often produced. If it is reused, it will cause problems such as crystallization of equipment and affect product quality. In many cases, enterprises adopt direct The treatment method of discharge has caused the waste of water resources, and also caused pollution and damage to the environment, which is not conducive to the implementation of national guidelines and policies for energy conservation and emission reduction. According to incomplete statisti...

AI Technical Summary

Problems solved by technology

[0009] Among the above-mentioned various methods for treating sodium sulfate wastewater, the chemical method removes sulfate radicals and cannot effectively recycle sodium sulfate, and the physical method has the disadvantages of complicated operation, high equipment investment and high operating costs

Some treatment methods need to add chemical reagents, which is easy to cause secondary pollution to raw water. At the same time, the requirements are relatively strict and the treatment process is relatively complicated.

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