Treatment of river water using modular gravity-driven ultrafiltration (GDU) for individual contingency water supply

In this work, hollow fibre ultrafiltration (UF) membrane operating under gravitational force were used to treat Escherichia coli bloomed water as well as contaminated surface water. The biofouling propensity of the UF membrane was investigated. The results showed that after the single filtration using the gravitational-driven UF unit, E. coli cells were accumulated on the membrane surface and gave fair rejection of 86.35–90.22% for initial E. coli cells concentrations of 5,000 and 10,000 MPN/ 100 mL, respectively. On the other hand, the double GDU membrane unit (filtration in series) could enhance E. coli removal up to 97.70–99.03% based on initial E. coli cell of 5,000 and 10,000 MPN/100 mL, respectively. For river water as feed, it was found that the permeate is free of pathogenic cells. No significant E. coli cells were found on the membrane surface of second filtration unit. Although there is ten-fold flux decrement by using a double filtration unit, the module is able to polish the contaminated water to potable water quality. The membrane could be cleaned using the simple backwash and the flux could be recovered up to 94%. In overall, this study has demonstrated the potential of using gravitational-driven UF to remove pathogens from contaminated river water.