AWWA WQTC64055

MWH and the City of San Diego have recently completed a pilot testing program at the North City Water Reclamation Plant (NCWRP) located in San Diego, CA. The purpose of the testing program was to evaluate various aspects of RO membrane integrity and integrity monitoring. During this study the integrity of new generation RO membranes offered for water reuse applications was assessed using traditional methods such as vacuum decay testing, vessel probing, on-line conductivity and sulfate monitoring and challenge testing with soluble dye and MS2 phage. In addition, a new method of RO integrity monitoring developed by Nalco Company which uses TRASAR® chemical was evaluated. The ability of the RO membranes to remove select endocrine disrupting compounds (EDCs) and pharmaceuticals and personal care products (PPCPs) was assessed by sampling feed and permeate of each system and evaluating them for a target list of 29 compounds commonly found in municipal wastewater. Lastly, the sensitivity of the tested integrity methods at detecting integrity breaches and the impact of integrity on EDC/PPCP passage were determined by purposely breaching one of the RO membrane systems and repeating testing. Results of this study showed the removal of MS2 phage by new generation RO membranes varied between 2-4 log (i.e. 99%-99.99%). In addition, results of the various monitoring methods tested on each membrane correlated to MS2 removal; however, the sensitivity of the methods varied. For instance, conductivity monitoring provided ~2 log removal, sulfate monitoring ~3 log removal and soluble dye testing ~ 4 log removal. Challenge testing with TRASAR® showed that the proposed method has the potential to provide a highly sensitive (>6 log) level of integrity monitoring. EDC/PPCP analysis showed all intact new generation RO membrane systems tested removed select compounds present in the feed wastewater to levels near or below MDL (ng/L). Results also suggest that certain EDC/PPCP compounds have different removal mechanisms and therefore, the increase in passage related to compromises in integrity may vary by compound and the type of breach. Includes 11 references, tables, figures.