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The project team of MWH and the City of San Diego recently completed a 12-month membranebioreactor (MBR) pilot testing program at the Point Loma Wastewater Treatment Plant (SanDiego, California). This U.S. Bureau of Reclamation funded study assessed the performance of fournewly developed MBR systems recently available to the U.S. municipal wastewater treatmentmarket. Pilot systems (capacities 5-20 gpm) were operated on raw municipal wastewater for atarget period of 3,500 hours under average and peak flow conditions. The productivity of thesystems was evaluated by measuring the increase in transmembrane pressure (TMP) underconstant flux conditions. Each system was also evaluated for its ability to meet Title 22 WaterRecycling Criteria for membrane systems as outlined by the California Department of HealthServices (CDHS). Test results from this study showed the newly developed MBR systemsoperated with cleaning average intervals of 300 - 1200 hours under average design conditions. Inaddition each system consistently produced effluent water quality expected from MBRtechnology for municipal wastewater treatment (i.e. BOD5 2 mg/L, ammonia 0.3 mg-N/L,turbidity 0.2 NTU and total coliform 100 CFU/100 ml) and based on results from this studywere granted conditional approval by CDHS. Though overall the new MBR systemsdemonstrated good productivity and water quality performance, the performance of several ofthe systems degraded during the test period due to issues such as loss of membrane integrity,mechanical failures and/or pilot design issues. MBR systems operated with minimal or nofouling under peak flux conditions over a 6-day period; however, the specific flux of thesubmerged MBR systems decreased during peaking (i.e. 4 hours per day) while that of theexternal MBR remained constant. Cost estimates of the newly developed MBR systems revealedcapital costs ($K) of 1 MGD capacity reclamation systems ranged from $7,990-9,850 whileO

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Edition: Vol. - No. Published: 03/01/2007 Number of Pages: 18File Size: 1 file , 570 KB