Organic Pollutants In The Electroplating Wastewater Treatment Compliance Emission Study

In this paper, we study the organic pollutants in the real wastewater from an electroplating factory. Through the exploration of the processes of coagulation, adsorption, micro electrolysis, Fenton, biochemical processes and their combined process, we design an economically visible process to provide reference to the discharge of the organic pollutant in EPWW to reach the new standard.It is suggested that there are significant differences in the content and types of the organic pollutants in EPWW from different electroplating processes. According to the actual effluent segregation system, the organic pollutants in the integrated wastewater are mainly from the oil removal process in the electroplating former treatment, in which COD is about 1300mg/L. The COD in the concentrated wastewater from Reverse osmosis (RO) is increased to 450mg / L after several times of concentration. Because the spent Electroless nickel plating bath has large amount of organic additives and lots of reducing agents such as HPO₂^- and HPO₃^-, the COD reaches 30g/L. So, It is hard to determine the featured organic pollutants because the wide range of sources of the pollutants in EPWW.To study the integrated wastewater, we compare the coagulation-biochemical process and the micro electrolysis-biochemical process. It is suggested that the removal rate of COD is lower by the method of coagulation, but the micro electrolysis-biochemical process can remove COD efficiently. It is determined that at the optimum conditions: the ratio of iron to carbon is 1:2, pH=3, he ratio of iron to wastewater is 1:3, the contact time is 20min and after aeration for 6h, the COD of effluent can reduced to 40.3mg/L.To study the concentrated wastewater from RO, it is suggested to use the Fenton-adsorption or biochemical process. The former's optimum conditions is: pH=3, H₂O₂=4.5mL/L, n(H₂O₂):n(FeSO₄)=1.1:1, the reaction time is 2h, the amount of activated carbon is 50g/L, the absorption time is 30min.The COD of effluent can reduce to 100 mg/L. The salinity has some effect to the biochemical process. Through the domestication of the activated sludge, the COD of effluent can reduce to 80 mg/L after aeration for 6h.Nickel and phosphorus resources have a certain value recycling from the Electroless nickel plating bath. With the addition of 40% NaOH=100mL/L, the recycling rate of Ni²⁺ is up to 96%; at the room temperature, with the addition of Ca(ClO)₂=240g/L, pH=8 and the reaction time is 48h, the rate of removal of TP is up to 99%. Based on the above experiments, an economically and technically feasible method is designed to treat EPWW. It is basically proven by calculating that the technical process possesses distinct social and economic benefits.