Research Of Treatment Technology Of Plating Wastewater By Heavy Metal Chelator And Its Engineering Practice

Reuse and resource of electroplating wastewater is essential to the reduction of heavy metal wastes in plating industry. The water quality can not meet the desired requirements for membrane system, which derived from the traditional alkaline precipitation. Heavy metal chelator is a kind of high molecular precipitant aiming at heavy metal ions, which is suitable for a deep purification treatment of heavy metal wastewater.DTC-E, a kind of heavy metal chelator, is synthesized with ethylenediamine, sodium hydroxide, carbon disulfide and other raw materials. We have confirmed dithiocarbamates as the active ingredient of this orange-red liquid product. Simulated copper wastewater has been treated with DTC-E. The results revealed that three factors have important impact on the removal efficiency of free copper ions, such as pH value, dosage of DTC-E and flocculant. Specifically, DTC-E can remove copper ions in a relative pH value wide, and the optimum dosage is 1.0 ratio of DTC-E to copper ions. Usage of flocculant will greatly improve the efficiency of Cu2+ by DTC-E.Besides, there is an engineering case that can be used to illustrate the applicability of heavy metal chelator. The rinse water and membrane concentrate can easily and reliably meet the emission standards set by "Emission standards for electroplating wastewater"(GB21900-2008), as long as which has been treaten by the united process of alkaline precipitation and following precipitation by heavy metal chelator.