Edi Chromium Electroplating Rinse Wastewater Treatment Research

At present, research on EDI mainly focused on treatment of wastewater containing divalent heavy metal cations,but few research on treatment of wastewater containing hexavalent chromium species.Because of high separation efficiency、convenience mutipation and low cost,EDI technology will make development of treatment of the chrome plating rinse wastewater.In this paper,on the basis of the ordinary three-compartment EDI device,An EDI device was assembled using the ion exchange resin as the anode chamber medium,which was applied in treatment of the chrome plating rinse wastewater.The results showed that applicability of EDI treatment for simulated chrome plating rinse wastewater was excellent, and the best parameters appeared with current density of1.2mA/cm2, influent flow of4L/h and pH of4.8.Under this condition,separation efficiency of Cr (VI) reached99.5%, and the current efficiency reached20.6%.Influence of EDI structure and operating parameters on its operation is as follows:(1)Anode chamber medium had a significant effect on EDI operation.Compared with dichromate solution as the anode chamber medium of EDI device,EDI with Resin as the anode chamber medium had a lower effluent concentration value and a higher current efficiency value.(2) Type of ion exchange resin in freshwater chamber had a significant effect on EDI operation. Compared with D301resin as the freshwater chamber medium of EDI device,EDI with D201resin as the freshwater chamber medium had a lower effluent concentration value and a higher current efficiency value,also had a shorter time to the stable period.(3)The current density had a significant effect on EDI operation.There would be a lower effluent concentration value and a higher current efficiency value for the EDI device in a high current density.(4) Influent flow had a significant effect on EDI operation. The greater the influent flow is, the higher effluent concentration is.At the beginning,the current efficiency of EDI with different inflow,which showed a decreasing trend and eventually reached a stable value,equaled each other constantly. This showed Influent flow had no effect on EDI operation.The result of EDI treatment of chrome plating rinse wastewater showed that:The presence of coexisting anions in the wastewater had no effect on the total current efficiency,and yet reduced the effective current efficiency of electro-migration of Cr(VI),meanwhile the separation efficiency of electro-migration of Cr(VI) declined when the effluent flow was4L/h; Because of the presence of coexisting cations in the wastewater,the total current efficiency and the effective current efficiency of electro-migration of Cr(VI) all reduced,and the separation efficiency declined when the influent flow was3L/h; The separation efficiency reached99.3%and the current efficiency reached20.4%when the effluent concentration of Cr(VI) was0.70mg/L,after foreign ions were pretreatment removed, which got closed to the result of EDI treatment of simulated chrome plating rinse wastewater.Above all, the process of EDI treating chrome plating rinse wastewater was applicable.