Validation of UF membrane plants for water recycling in Victoria: A test program using challenge organisms to determine reduction in virus removal performance due to compromised membrane integrity

All Class A water recycling schemes in Victoria require endorsement from the Victorian Department of Health (Vic DH), in addition to approval from EPA Victoria. Vic DH has published validation guidelines for Class A treatment processes to ascertain that the adopted treatment processes are achieving the targeted pathogen reduction. South East Water recently constructed three recycled water treatment plants, all of which use ultrafiltration systems supplied by Pall Corporation. These were pre-validated in the US for compliance with USEPA Long Term 2 Enhanced Surface Water Treatment Rule Toolbox Guidance Manual (lT2ESWTR) and USEPA Membrane Filtration Guidance Manual (MFGM). However, these validation studies were carried out on intact systems; there was a lack of adequate information demonstrating the performance of the membrane modules with compromised integrity, i.e. broken fibre(s). Accordingly, a test program was undertaken using challenge organisms (MS2 bacteriophage) to determine the reduction in virus removal performance resulting from cut fibre(s). The results were compared with calculated values using bubble point theory for protozoa removal, as per the MFGM. The results apparently showed 'that the calculated value for protozoa was more conservative than the measured value using MS2. This paper gives details of the methodology adopted and results obtained, and discusses the implications for plant monitoring and operation.