Closed cyclic processing method for low-concentration acid wastewater during industrial production

Abstract

The invention relates to a closed cyclic processing method for low-concentration acid wastewater during industrial production, which comprises the following steps of: allowing the low-concentration acid wastewater containing heavy metals to flow into an aeration tank and then throwing into a pH value adjusting pool after aeration treatment; adding a saturated sodium hydroxide solution or industrial solid sodium hydroxide into the pH value adjusting pool, adjusting a pH value of the solution to be 3-4, allowing a lower-layer turbid liquid containing precipitants to enter into a reaction tank I after filtering and deposition, allowing a supernatant clear solution to enter into an electrodialysis reactor for electrodialysis, and concentrated water dialyzed from the electrodialysis reactor to enter into the reaction tank I; adding waste acid into the reaction tank I, and feeding the fully-reacted liquid in the reaction tank I into a reaction tank II; adding lauryl sodium sulfate serving as a surfactant into the reaction tank II for reaction, and filtering off a lower-layer substance containing iron; and feeding the supernatant liquid into an electrolysis reaction tank to recover zinc through electrolysis, placing the recovered zinc into the reaction tank II to continuously perform the reaction to recover the iron, and recovering an electrolysis residual liquid to prepare sodium slat crystals. By the method disclosed by the invention, valuable metals in precipitation residues can be recovered, and the content of heavy metal ions in processed discharge water is low.

Description

technical field [0001] The invention relates to a method for treating acidic wastewater discharged during industrial production, especially for treating metal products, and belongs to the field of wastewater treatment. Background technique [0002] The acid wastewater currently produced in the metal products industry mainly comes from water washing after pickling, electroplating, and hot-plating. At present, the existing industrial acid wastewater treatment process mainly adopts the neutralization precipitation method. The method is mainly to increase the pH value of acidic wastewater by adding alkaline chemicals, and make the heavy metal ions in the wastewater oxidize, precipitate and flocculate to form hydroxide or carbonate precipitation, and landfill the precipitated sludge Disposal, discharge of the treated neutral alkaline wastewater. Commonly used neutralizers include quicklime, milk of lime and limestone. This kind of method can remove a variety of heavy metal ion...

AI Technical Summary

Problems solved by technology

The invention patent of the announcement CN1899985A provides a method for the treatment of copper, chromium, cadmium, nickel heavy metal electroplating waste liquid and the recycling of heavy metals. The steps of complexation, ultrafiltration, decomplexation, ultrafiltration, and reverse osmosis are used to recover heavy metal ions, and finally the waste water Meet the discharge standard, return the concentrated heavy metal ions to the electroplating bath, enrich and finally adopt the neutralization precipitation method to precipitate the iron ions, solve the problem of excessive iron ion concentration, and still produce a large amount of sludge that cannot be disposed of

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