Water Journal : Water Journal September 2012-1
refereed paper membrane technology water SEPTEMBER 2012 63 Abstract Full-scale ultrafiltration membrane challenge testing with MS-2 bacteriophage was undertaken at the Glenelg Recycled Water Treatment Plant (GRWTP) as a validation activity to verify virus removal accreditation. Four out of eight membrane units were tested and tests repeated on three separate days at normal operating conditions. Based on using a paired feed filtrate LRV method and the 5th percentile, an LRV of 2.5 log10 was determined. Introduction Membrane technology is becoming widely used in Australia and ultra-filtration (UF) membrane technologies have been installed in several South Australian metropolitan alternative water schemes, including the Glenelg-Adelaide Recycled Water Scheme (GARWS), the Aldinga Southern Urban Reuse Scheme and the Christies Beach "C-plant" upgrade. UF membranes provide a physical barrier to pathogens including bacteria, protozoa and viruses, and the degree of removal is based on several factors including the organism, membrane, operating conditions and water quality (Jacangelo et al., 2006; Jacangelo et al., 2008; Humbert et al., 2011). The use of membrane systems is dependent on the pathogen log removal value (LRV) accredited by a regulatory authority. The LRV accreditation for specific installations may depend on the extent of validation testing by the supplier at a pilot or full- scale, the experience of the regulator and operator, and the existence of other comparable installations. Furthermore, the relationship between membrane integrity and LRV removal will influence operational monitoring to prevent passage of pathogens through the barrier. Direct (i.e. air pressure decay testing) and indirect (i.e. filtrate turbidity) monitoring are crucial for integrity monitoring (Crozes et al., 2002; Farahbakhsh et al., 2003) and compliance for the regulator. The GARWS is designed to supply up to 34ML/d of alternative water to the Adelaide parklands, central business district and surrounding councils for municipal open space irrigation (unrestricted) and dual reticulation (indoor/ outdoor) applications. The source water for the scheme is chlorinated secondary effluent from the Glenelg Wastewater Treatment Plant. The Glenelg Recycled Water Treatment Plant (GRWTP) train comprises four pathogen treatment barriers -- secondary treatment, UF, ultra-violet (UV) disinfection and chlorine disinfection (Figure 1). The health regulator initially approved the scheme for municipal applications in 2009 and accredited an LRV of 2.0 log10 for virus removal through the UF membrane system, but indicated that this could be revised subject to full-scale challenge testing. Prior to challenge testing, dual-reticulation approval was provided subject to an increase in the R Regel, C Heidenreich, A Keegan Four out of eight membrane units were tested and an LRV of 2.5 log10 determined FULL-SCALE MS2 TESTING OF THE GLENELG RWTP UF MEMBRANE PROCESS Figure 1. GARWS process schematic. Table 1. Summary of LRVs for pathogen removal at the GARWS. Barrier Dual reticulation (Feb 2010) Dual reticulation (Mar 2011) V B P V B P Secondary treatment 1.0 1.0 0.5 1.0 1.0 0.5 UF 2.0 3.0 3.0 2.5 3.0 3.0 UV 1.0 4.0 4.0 1.0 4.0 4.0 Chlorine 2.5 4.0 0.0 2.0 4.0 0.0 TOTAL 6.5 12.0 7.5 6.5 12.0 7.5 Dual retic.* 6.5 5.0 5 6.5 5.0 5.0 Municipal* 5.0 4.0 3.5 5.0 4.0 3.5 V = virus, B = bacteria, P = protozoa *Minimum LRV requirements according to NRMMC-EPHC-AHMC (2006).
Water Journal November 2012-1
Water Journal August 2012