Managing biofilms in ultrafiltration membranes within a point-of-use drinking water system

The presence of biofilms in ultrafiltration [UF] membranes within drinking water treatment systems can result in shortened operational capability if not managed appropriately. The aim of this study was to demonstrate the use of electrochemically generated slightly acidic hypochlorous acid [HOCl] continually dosed in-situ within a decentralised point-of-use drinking water treatment system to manage biofilm formation, thus maintaining UF membrane permeability. This study demonstrated that continuous dosing of HOCl managed the UF membrane permeabilty over a 2.25 year period with varying flow rates and seasonal variations. Previous investigations have demonstrated HOCl’s superior efficiacy at managing biofilms in comparison to sodium hypochlorite [NaOCl], and with many UF membrane manufacturers advising against continuous dosing of chlorine solutions that damage materials, resulting in irreversible breakthrough. However, data presented here indicates no damage to material, resulting in extended operational periods without regular deep cleans of UF membranes.