Assessment of Ultrafiltration Cleaning Protocols in Drinking Water Treatment Processes

Abstract

Membrane-based processes efforts are focused on mitigating membrane fouling by optimizing operating conditions, especially when low quality surface waters are treated. The study conducted here was driven to evaluate the current measures applied to mitigate fouling in Ultrafiltration (UF) stages when integrated as a pre-treatment of the Reverse Osmosis (RO) in a Drinking Water Treatment Plant (DWTP). First, the effect of coagulants in fouling and water quality was evaluated by using synthetic and surface waters in bench-scale. Both aluminum and ironbased coagulants rejected the organic compounds when dosed above 1 mg·L -1 . Also, micro-coagulation with FeCl 3 previous to the UF impacted positively the membrane performance. Then, two modes of operation were proposed and tested in bench-scale to improve the cleaning strategies when filtering waters from different sources. The results highlighted the feasibility to apply a different cleaning protocol when groundwater was filtered as it would improve the water yield and production by elongating the filtration times. To conclude, an exploratory analysis reviewed the membrane performance and cleaning strategies in the Ultrafiltration stage at full-scale during 1 year of operation. The results showed high variations in Specific flux (Js) throughout the year and, also, suggested that chemical cleaning procedures were being applied in excess.