A kind of industrial sewage treatment system and sewage treatment method

Abstract

The invention relates to an industrial sewage treatment system and a sewage treatment method. The industrial sewage treatment system comprises a regulation pool which is used for collecting sewage, wherein a pretreatment system which mainly comprises a V-shaped filter tank is connected behind the regulation pool, and a first-stage ultrafiltration and reverse osmosis system is connected behind the pretreatment system. The industrial sewage treatment system is characterized in that behind a reverse osmosis unit in the first-stage ultrafiltration and reverse osmosis system, reverse osmosis concentrated water of one path enters an at-least-one-stage frequent-reverse-pole electrodialysis system connected with the path and is subjected to concentration, and plain water of another path is connected with a recycled water pool or communicated with a recycled plain water outlet pipe of the recycled water pool; and a concentrated water outlet behind the frequent-reverse-pole electrodialysis system is connected to a monovalent-bivalent-separation electrodialysis system which can be used for separating monovalent salt and bivalent salt, an MVR evaporation device which is used for concentrating and recovering the monovalent salt so as to obtain crystallized sodium chloride is connected behind the monovalent-bivalent-separation electrodialysis system, a plain water outlet behind the monovalent-bivalent-separation electrodialysis system is connected with an at-least-another-stage frequent-reverse-pole electrodialysis system, a plain water outlet behind the frequent-reverse-pole electrodialysis system is connected with the recycled water pool, and a concentrated water outlet behind the frequent-reverse-pole electrodialysis system is connected with another MVR evaporation device which can be used for obtaining sodium sulfate crystal salt.

Description

Technical field [0001] The invention relates to an industrial sewage treatment system and a sewage treatment method capable of realizing zero discharge, and belongs to the technical field of environmental protection water treatment. Background technique [0002] "Zero discharge" of sewage means that after reuse of industrial water, this part of the high salt content and pollutants is concentrated into sewage and all (over 99%) is recycled and reused, without any waste liquid discharged from the factory. Salts and pollutants in the water are concentrated and crystallized as solids and discharged from the plant to the waste treatment plant for landfill or recycled as useful chemical raw materials. [0003] The current zero-discharge sewage treatment technologies mainly include: pretreatment + ultrafiltration + reverse osmosis + multi-effect evaporation, see figure 1 As shown, the specific content is: [0004] After the biochemical treatment, each stream of influent first enters the wa...

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Problems solved by technology

[0016] The so-called "zero discharge" in the above-mentioned zero-discharge sewage treatment is not zero discharge in the true sense. It cannot realize the effective separation and utilization of various substances in the sewage; it just reuses the sewage, and the reused water Ions and solids are transformed into crystalline solids in the above process, which need to be safely landfilled as hazardous solid waste, requiring the construction of a high-investment hazardous solid waste landfill; in addition, a large-volume sewage temporary storage is also required Generally, the capacity of the sewage temporary storage pool needs to be hundreds of thousands or even nearly one million cubic meters, and the investment is hundreds of millions of yuan; and the secondary environmental pollution that may be caused by improper treatment of crystalline solids and the hidden environmental risks of the sewage temporary storage pool; this part of waste residue needs to be Safely landfill as hazardous waste; in addition, crystalline solids contain high concentrations of metal ions and organic matter. Once handled improperly, the toxic heavy metal ions contained in the buried solid matter will pollute our groundwater system once dissolved, so this This technology is only a "zero emission" technology at the economic level

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