Crossflow electro-microfiltration of oxide-CMP wastewater

In this work, an electrically enhanced crossflow microfiltration (EECMF) system was used for the treatment of oxide-CMP wastewater under different operating conditions to investigate their effects on filtration rate. Oxide-CMP wastewater was obtained from a wafer fab and characterized by various standard methods. A membrane with a cut size of 0.1mum was used in the EECMF system. Operating parameters studied include crossflow velocity, transmembrane pressure, mode of electric field, electric field strength, and mode of backwashing. The filtration rate was found to increase with increasing crossflow velocity, electric field strength, and transmembrane pressure when operated below the critical electric field strength. Experimental results indicated that intra-filtration-run backwashing outperformed inter-filtration-run backwashing in terms of filtration rate. Experimental results also showed that the filtration rate for pulsed mode operation was greater than that of no electric field application, but worse than that of continuous mode operation. Using the present EECMF system, a fairly good quality of filtrate was obtained. It was found that the filtrate having a turbidity of 0.39 NTU is achievable. Thus, the filtrate could be reused for non-process applications. (C) 2002 Elsevier Science Ltd. All rights reserved.