In order to make the electroplating waste water reach the national discharge standard, people not only carried out a lot of research on the method of waste water treatment, but also carried out reforms both from the plating liquid itself and the post-plating rinsing method.
In electroplating process, research and exploration of non-cyanide plating, low-chromium plating and chromium-free passivation, low-chromium chrome plating, trivalent chrome plating or chrome-plating, and cadmium oxide plating have been carried out. Progress. If no cyanide galvanizing, low chromium passivation, chromium chrome plating and other processes have been widely used throughout the country to use, significantly reducing the national electroplating industry, the use of sodium cyanide, chromium anhydride. The commissioning of these new processes fundamentally eliminates or reduces the environmental pollution caused by the highly toxic cyanide and chromate.
In the cleaning method, the simple cleaning method in the past was changed, and a combination of multiple recovery, multi-stage countercurrent rinsing, and spray leaching was used. This rinsing method not only can save a large amount of cleaning water, but also can recover most of the plating solution while reducing the concentration of harmful substances in the rinsing water and making the wastewater treatment easier.
In addition to reforming the plating solution itself and the rinsing method, the electroplating wastewater treatment method has also been further studied, and many gratifying results have been obtained. Currently widely used in the production of methods are: ferrous sulfate ferrous wastewater treatment method, sodium bisulfite method, electrolytic method, ion exchange method, surfactant method, activated carbon adsorption method, ferrite method, Iron powder filtration method, coke iron scrap method, electrodialysis method, reverse osmosis method, etc.alkaline oxidation method for the treatment of cyanide-containing wastewater, electrolytic method, ion exchange method, etc.; wastewater containing chromium and copper is mostly ion exchanged, etc. For a variety of metal ion mixed wastewater, air floatation is used. The production operation shows that the above methods have their own characteristics and can effectively treat the electroplating wastewater. Everyone can choose according to the actual situation of the unit.
With the continuous development of science and technology, processing equipment, detection and control instruments are also more complete, enabling people to combine several single processing technologies and apply them to electroplating wastewater treatment to achieve the recycling of resources and the closed cycle of rinse water.