Investigation of Nanofiltration Process in Nickel, Chromium and Cadmium Removal from Industrial Wastewater

With developing technologies and various industrial activities, the produced wastewater from industrial activities makes a serious threat for environment. When this kind of wastewater, which includes heavy metals from miscellaneous industrial activities, enters to environment prepares adverse effects on human beings and food chain organisms. There are many investigations about heavy metals removal from industrial wastewater based on precipitation, ion exchange, and biological processes. However, these days, the performance of membrane processes such as nanofiltration is focused as an appropriate process and many investigators are working on it. The main purpose of this work is the evaluation of nanofiltration process on heavy metals such as nickel, chrome, and cadmium from synthetic industrial wastewater. Also, the effects of operating parameters on nanofiltration process are investigated. In this work, a nanofiltration pilot with capacity of 40 m3/day, which consists of 1 and 5 micron filters and a permeable polyamide membrane (NF90-4040), is used and the effect of heavy metals concentration increase on the removal efficiency of one or mixed of all heavy metals are evaluated. It is concluded that the performance of nanofiltration with increase of heavy metals concentration improved and the maximum heavy metals removal efficiency is occurred when the concentration of heavy metals is equal to 100 mg/L. The average removal efficiency of one and mixed of all heavy metals is 95.4 and 97.5%, respectively. Moreover, the operating pressure of nanofiltration process with increase of heavy metals concentration, decrease but the recovery rate of membrane increase. The average recovery rate of membrane in one and mixed of all heavy metals removal condition is 72.8 and 72.4%, respectively. Also, among the heavy metals the maximum recovery rate and the minimum operating pressure in nanofiltration process belong to cadmium.