An Experimental Study On The Typical Electroplating Wastewater Treatment And Engineering Implement In Jinhua

Based on the electroplating wastewater produced by a plating factoryin Jinhua, an experiment was conducted to investigate the parameters ofcyanide and organic pollutant removal in the comprehensive wastewaterby hydrogen peroxide catalytic oxidation and the feasibility of organicpollutant treatment by biochemical process. A wastewater treatmentproject was then designed and implemented on the basis of experimentalresults.Through the optimization of main factors on the catalytic oxidation ofcyanide by hydrogen peroxide, a better reaction condition with an initialconcentration of cyanide4.8mg/l and of COD_Cr530mg/l was determinedas follows: the initial pH is4.0, the dose of fH₂O₂is0.6g/l, and the reactiontime is120min. Under this condition, the removal ratio of cyanide was97.3%and the final concentration of cyanide was0.13mg/l, lower than thedischarge standard of0.3mg/l; the removal ratio of COD_Crwas42.1%andthe final concentration of COD_Crwas307mg/l.The treatment of pretreated wastewater by activated sludge methodwas investigated. The results showed that it is feasible to remove theorganic pollutant in the electroplating wastewater by biochemical process.When the influent COD_Crconcentration was253mg/l, the removalefficiency was76.8%after24h aeration.Based on the experimental study, the process flow of the electroplating wastewater treatment was designed as follows. Cyanide in cyanidewastewater and comprehensive wastewater were firstly destroyed byalkaline chlorination and hydrogen peroxide catalytic oxidation,respectively. All wastewater was then treated by the neutralization-flocculation-precipitation-biological contact oxidation process. Thedesign treatment capacity was100m3/d. Based on analysis of technologyand economic, the total engineering investment was RMB300thousandand the treatment cost was RMB7.62yuan/m3.The operation results indicated that the effluent concentration ofcyanide with hydrogen peroxide catalytic oxidation was lower than thedischarge standard of0.3mg/l when the influent concentration of cyanidewas2.2⁴.3mg/l. The effluent concentration of COD_Crwith hydrogenperoxide catalytic oxidation was268³46mg/l when the influent COD_Crwas450⁵64mg/l. The effluent COD_Crwas56⁷8mg/l, lower than thenew discharge standard of80mg/l, when the electroplating wastewater wastreated by the biological contact oxidation process.The experimental study and practical application showed that it iseffective to destruct the cyanide and organic pollutant by hydrogenperoxide catalytic oxidation and to remove the organic pollutant bybiochemical process.