A high-salt wastewater treatment system and process for salt separation and concentration

Abstract

The invention discloses a high-salt wastewater salt separation and concentration treatment system, which includes a pretreatment device, a selective ion electrodialysis device, a nano-membrane distillation device, a thin-film MVR evaporation device aiea, a first heating device, a second heating device, and a first crystallization device. Cation selective membranes and monovalent anion selective membranes are alternately arranged between the cathode and anode of the selective ion electrodialysis device; the pretreatment device is used for coagulation, precipitation and chemical conditioning of the high-salt wastewater to be treated. The nano-membrane distillation device is equipped with a block copolymer modified non-porous nano-membrane, and the thin-film MVR evaporation device is equipped with a polymer elastic film. The first crystallizer adopts evaporation crystallization, and the second crystallizer adopts freeze crystallization. Further, the invention also discloses a process for treating high-salt wastewater by separating and concentrating salt. The present invention can realize solid waste reduction and waste salt recycling through salt separation, use waste heat and high-efficiency evaporation to reduce concentration cost, and has simple operation, stable and reliable operation, and low investment and operation cost.

Description

technical field [0001] The invention belongs to the field of recycling waste water and waste salt and zero discharge, and in particular relates to a high-salt waste water salt separation and concentration treatment system and process. Background technique [0002] With the rapid development of industry and the rapid growth of population, the available fresh water resources are getting less and less, and the shortage of water resources and the pollution of water environment have become the bottleneck restricting economic development. To this end, the state has introduced water-saving policies and developed wastewater concentration and zero-discharge technologies to increase the water reuse rate and reduce the amount of water drawn by enterprises. The accompanying problems of safe and reasonable disposal and resource utilization of high-salt wastewater and waste salt, The salt content of flue gas desulfurization wastewater, oil and gas production water, and RO concentrated wat...

AI Technical Summary

Problems solved by technology

In the existing technology, the typical process adopted by domestic power plant wastewater "zero discharge" is the "front-end pretreatment + double-membrane concentration + evaporation crystallization" process, but there are some common problems: pretreatment softening dosage is large, and there are many sediments; Chloride ions contained in high-concentration brine are easy to cause corrosion to equipment; system leakage causes salt formation; calcium, magnesium, silicon, etc. cause scaling; organic matter in the medium is accompanied by inorganic precipitates. If clarification pretreatment is not good, micro / ultrafiltration cleaning is frequent; Using nanofiltration for salt separation, the performance of nanofiltration membrane decays quickly and the recovery rate is low; when conventional electroosmosis is used for concentration, the positive membrane only allows cations to pass through, and the anion membrane only allows anions to pass through, and the influent water will scale against hardness, etc. The requirements for active ions are high, otherwise the membrane surface is easy to scale

Moreover, in the process of membrane concentration or thermal concentration, there are long processes, difficult operation control, membrane fouling, evaporator scaling, and the system cannot operate stably; the operation cost is high; the amount of sludge waste is large, and crystallized miscellaneous salts are hazardous wastes. high cost issues

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