Zero discharge of electroplating wastewater The system mainly uses membrane separation technology. Because membrane separation technology has the advantages of low energy consumption, no phase change, no pollution, and high separation efficiency and concentration times, appropriate membrane separation is used to concentrate the rinse water of electroplating solution, and the concentration times can reach 100 times (in volume). The concentrated solution after membrane separation returns to the electrolytic cell after proper treatment to reach a certain nickel ion concentration, that is, nickel recovery. The permeate of the membrane system, that is, pure water, can be directly returned to the bath of the plating parts, thus realizing zero discharge of electroplating wastewater. Therefore, the zero discharge system of electroplating wastewater not only does not cause secondary pollution, but also recovers harmful heavy metals in the wastewater, turning harm into treasure and reusing water resources.
(a) Treatment of pickling wastewater:
Adjust the pH value of pickling wastewater to 6~9 with sodium hydroxide solution, aerate it with air for 2~12 hours, remove the precipitation, remove the metal cations through the adsorption of hydrogen type strong acid cation exchange resin, and then concentrate and recover the low salt water through the reverse osmosis device; The regeneration liquid of hydrogen type strong acid cation exchange resin is transported to the acid dissolving tank; After being concentrated by the reverse osmosis device, the high salt water is evaporated and concentrated to the solid after chelating resin and activated carbon adsorption, pH adjustment and flocculation treatment, and becomes harmless solid impurities. The condensed water is recycled for use, or the high salt water is treated by chelating ion exchange resin, and then discharged directly after the wastewater COD reaches the standard through ultraviolet photocatalytic oxidation;
(b) Treatment of cyanide containing wastewater:
The pH value of cyanide containing wastewater is controlled at 7~10, and the cyanide ion in wastewater is removed by the anion exchange resin treated by the meridian anion, Electroplating wastewater treatment equipment Then the copper and zinc ions in the wastewater are removed by cation exchange resin adsorption, and enter the reverse osmosis system. The low salt water is reused. The high salt water is removed heavy metal ions by chelating ion exchange resin. After pH adjustment and flocculation treatment, it is evaporated and concentrated to the solid to become harmless solids. The condensate is recycled for use, Or the high salt water is treated by chelating ion exchange resin, and then discharged directly after the COD reaches the standard through ultraviolet photocatalytic oxidation;
The anion exchange resin treated with complex anion is saturated after adsorption and regenerated with 4~6mol/L hydrochloric acid. The regenerated solution is recycled after removing hydrogen cyanide;
(c) Treatment of mixed wastewater from passivation and electroplating rinsing:
Control the pH value of the mixed wastewater of passivation and electroplating rinsing at 0~5, and remove hexavalent chromium ion through anion exchange resin adsorption; Adjust the pH value of wastewater to 5~10 to form sediment, and the sediment will be sent to the acid dissolving tank after pressure filtration and cleaning; The clarified solution is adsorbed and removed by the anion exchange resin with complex anion treatment, and then the metal cation is removed by the hydrogen type strong acid cation exchange resin. The low salt water is reused by the reverse osmosis system, and the high salt water is removed by the chelating type ion exchange resin. The high salt water is evaporated and concentrated to the solid after pH adjustment and flocculation treatment to become harmless solid impurities. The condensate is recycled for use, Or the high salt water is treated by chelating ion exchange resin, and then discharged directly after the COD reaches the standard through ultraviolet photocatalytic oxidation;
The zero discharge system of electroplating wastewater gives full play to the advantages of special membranes. After the electroplating and circuit board wastewater is treated by this process, valuable metal ions (nickel, copper, chromium, etc.) in the wastewater can be recycled after membrane concentration. The permeate of the wastewater after membrane treatment can be reused as process water, which not only saves costs but also realizes zero discharge of wastewater. The zero discharge system of electroplating wastewater adopts electromechanical integration design, with high degree of automation, simple operation and maintenance, easy standardized management, small floor area, few auxiliary facilities, reasonable equipment configuration, low investment and low operation cost.
