Method for co-treating chromium-containing wastewater and acidic wastewater

Abstract

A method for co-treating chromium-containing wastewater and acidic wastewater includes the following steps: filtering pretreating of the acidic wastewater, to be more specific, filtering particulate matters of 5-30 mu m or more; (2) film concentration of the acidic wastewater, to be more specific, using a high-efficiency film concentration technology for concentration the filtered acidic wastewater; and heating the filtered cold-rolled acidic wastewater to 50 to 100 DEG C until the concentration of the acid in the concentrated liquid is greater than 2 to 10%; (3) mixing of the acidic wastewater concentrate with the chromium-containing wastewater, wherein the acid in the acidic wastewater concentrate can be used to adjust the pH of the chromium-containing wastewater to 2-5; and (4) neutralization and precipitation. According to the method, the operating cost of the waste water is saved, the amount of discharged waste water and the sludge production are reduced, the disposal cost of chromium-containing sludge is saved, and the method has good social and environmental benefits.

Description

technical field [0001] The invention belongs to the technical field of water treatment, and in particular relates to a method for co-processing chromium-containing wastewater and acidic wastewater. Background technique [0002] Chromium and its compounds are widely used in a series of industries such as metallurgy, chemical industry, mineral engineering, electroplating, chromium production, pigments, pharmaceuticals, light industry textiles, chromium salts and chromium compounds. These industries will produce a large amount of chromium-containing wastewater, and the compounds of chromium are mainly in the form of trivalent (such as Cr 2 o 3 ) and hexavalent (such as CrO 4 2- or Cr 2 o 7 2- ) form exists. The toxicity of hexavalent chromium is the strongest, which is about one hundred times that of trivalent chromium. [0003] Pickling is one of the indispensable processes in cold rolling mills. During the production process, the cold-rolled steel needs to be pickled...

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Problems solved by technology

[0010] However, the main problem of the lime neutralization process is that the treated wastewater has high conductivity and high calcium ion content, which is not conducive to subsequent desalination and reuse. The concentrated brine produced by desalination and reuse has no good outlet and can only be used Slag flushing and other occasions that do not require high water quality, but the impact on the subsequent use of slag needs further research; in addition, a large amount of sludge will be generated during the process of neutralization and sedimentation of wastewater, which cannot be utilized as a resource and can only be landfilled or for other treatment, and the cost of sludge disposal is increasing year by year

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