Method and system for treating flue gas desulfurizing wastewater by stages and qualities

Abstract

The invention discloses a method and a system for treating flue gas desulfurizing wastewater by stages and qualities. The method comprises the following steps: A, using a water softening device to remove heavy metal ions and suspension matters in the desulfurizing wastewater; B, using an ultrafiltration device to treat a supernatant in step A; C, using a nanofiltration device to treat a supernatant in step B, and separating non-monovalent ions and monovalent ions, so as to obtain nanofiltration clear liquid and nanofiltration concentrated liquid; D, using a reverse osmosis device to respectively treat the nanofiltration clear liquid and the nanofiltration concentrated liquid which are obtained in step C, so as to obtain first reverse osmosis concentrated liquid, second reverse osmosis concentrated liquid and purified water; E, removing silica gel matters out of the first reverse osmosis concentrated liquid and the second reverse osmosis concentrated liquid which are obtained after step D; F, evaporating and concentrating, so as to obtain sodium and potassium crude salt, calcium and magnesium crude salt and purified water. The treatment method has the advantages that by adopting two-stage water softening, two-stage membrane treatment and two-stage evaporation and concentration, an S2M2E2 treatment technology is formed; the blockage of a filtering membrane and the scaling of an evaporator in the flue gas desulfurizing wastewater treatment process are reduced, and the utilization rate of a product and the treatment efficiency are improved.

Description

technical field [0001] The invention relates to the technical field of waste water treatment, in particular to a method and system for classifying and classifying waste water from flue gas desulfurization. Background technique [0002] The impurities in desulfurization wastewater come from flue gas and limestone for desulfurization, mainly including suspended solids, supersaturated sulfite, sulfate and heavy metals, many of which are the first category of pollutants required to be controlled in the national environmental protection standards. , Salt concentration and impurity enrichment in waste water, desulfurization waste water treatment is difficult and costly, resulting in serious water pollution. [0003] The flue gas desulfurization process determines the high concentration of suspended solids in desulfurization wastewater, Ca 2+ , Mg 2+ 、Na + 、K + Isocations and SO 4 2- , CO 3 2- , SiO 3 2- , Cl - The anion content is high, and there are a lot of silica gel...

AI Technical Summary

Problems solved by technology

At present, membrane treatment is mainly used for flue gas desulfurization wastewater, and there are the following problems: (1) Different degrees of membrane clogging; (2) Scaling phenomenon during evaporation; (3) Large energy consumption; (4) The use value of products is low Low

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