Pre-filtration for enhancing direct membrane filtration of graywater from washing machine discharges

Direct membrane filtration is a candidate technology with great potential for treating and reusing domestic graywater. However, membrane performance and fouling remain as a main problem in direct membrane filtration processes. In this work pre-filtration by using common materials was evaluated as a potential alternative to deal with fouling, increase contaminants removal and improve performance of direct membrane filtration of graywater. Pre-filtration by itself reached removals of total solids and total COD greater than 30% for powder detergent graywater, but was less effective on liquid detergent graywater. Pre-filtration improved microfiltration and ultrafiltration performance; it was denoted by flux increase and reduction of fouling rate. In addition, pre-filtration is cost-effective, is easy to conduct, and there is no sludge generation. Therefore, pre-filtration is recommended as a pre-treatment process for micro- and ultrafiltration systems.