Performance and fouling characteristics in a pilot-scale reverse osmosis membrane system for microelectronic wastewater treatment

Abstract

The microelectronic industry faces the significant challenge of managing vast volumes of wastewater containing toxic and harmful pollutants. While the Ultrafiltration-Reverse Osmosis (UF-RO) system has gained recognition as a potential solution for the reclamation and reuse of such wastewater, there is a lack of comprehensive understanding on its performance and membrane fouling conditions in the context of actual microelectronic wastewater. In this study, we continuously monitored the performance of a pilot-scale UF-RO system treating microelectronic wastewater. The RO membrane was subject to autopsy characterization at the end of its operation. The UF pretreatment performance remained consistent, with the UF-RO system showcasing high removal efficiency (>99.5 %) for tetramethylammonium hydroxide (TMAH), the primary pollutant in the microelectronic wastewater. Inorganic, organic, and biofouling were identified on the membrane surface, with the biofouling as the predominant form. A microbial community analysis showed that Proteobacteria and Bacteroidetes were the dominant bacteria on the membrane surface at the phylum level, while Alicycliphilus, Chryseobacterium, and Flavobacterium were predominant at the genus level. Fouling characteristics and degrees varied across the four stages, with the fouling in the 2nd stage being the most severe. Interestingly, an increased concentration of TMAH in the influent of the 4th stage seemed to inhibit the development of biofouling to some extent. This study offers valuable insights into the practical performance of the pilot-scale UF-RO technology when treating microelectronic wastewater and lays the groundwork for developing strategies to address membrane fouling concerns within the microelectronics industry.