Separated flotation tank-capacitive deionization membrane distillation technology combined electroplating wastewater purification and recycling process system

Abstract

A separated flotation tank-capacitive deionization membrane distillation technology combined electroplating wastewater purifying and recycling process system belongs to the technical field of wastewater treatment and is formed by connecting a water inlet tank, a membrane distillation heating tank, a pH regulating tank, an air floatation tank, a capacitive deionization membrane distillation reactor, a condenser, a power supply, a computer and a clean water tank. High-salinity industrial wastewater such as electroplating wastewater is pretreated by using an air flotation method, volatile pollutants such as ammonia nitrogen and cyanide in the wastewater are efficiently removed, and heavy metals and salt substances in the wastewater are further adsorbed, intercepted and recycled through the process of a capacitive deionization membrane distillation reactor, so the heavy metals in the electroplating wastewater are efficiently intercepted and recycled, the effluent water quality is highly purified, the zero discharge treatment of the electroplating wastewater is achieved, the air flotation pretreatment process and the introduction of the electrode plate in the capacitive deionization membrane distillation reactor significantly alleviate the membrane pollution/membrane wetting trend of the distillation membrane, the service life of the distillation membrane is prolonged, and the operation cost of membrane cleaning/membrane replacement is reduced.

Description

technical field [0001] The invention belongs to the technical field of wastewater treatment, and relates to a method for treating and reusing high-salt industrial wastewater such as electroplating wastewater, in particular to a method of combining air flotation with capacitive deionization membrane distillation technology to improve the volatilization of ammonia nitrogen, cyanide, etc. The removal rate of permanent pollutants, improve the desalination efficiency of saline wastewater and slow down the membrane fouling / membrane wetting tendency of the distillation membrane, the purification and reuse process system that prolongs the service life of the distillation membrane. Background technique [0002] As one of the three major polluting industries in the world, electroplating may contain heavy metals such as chromium, nickel, copper, cadmium, and zinc, as well as toxic and harmful pollutants such as cyanide, acid and alkali, brighteners, and additives in the wastewater gener...

AI Technical Summary

Problems solved by technology

However, during MD operation, the high temperature on the hot side and the gradually rising pH (pH>7) will cause a large amount of ammonia nitrogen in the raw material liquid to be converted into gaseous ammonia (NH 3 ) (pH>7, NH 4 + +OH - →NH 3 ·H 2 O; and when pH > 11, mainly exists as gaseous ammonia), NH 3 It is very easy to pass through the pores of the MD hydrophobic membrane to reach the permeate on the cold side, thereby reducing the removal rate of ammonia nitrogen in the separation process of the MD membrane

Previous studies have found that the rejection rate of COD, protein, polysaccharide and other pollutants in the MD membrane separation process can reach more than 90%, and the rejection rate of phosphate is even as high as 100%, but the removal rate of ammonia nitrogen is only about 70%.

At the same time, electroplating wastewater contains a large amount of volatile and toxic pollutants such as cyanide, which can easily enter the permeation side of membrane distillation in gaseous form under the high temperature environment of membrane distillation, thereby deteriorating the quality of effluent water

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