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The Sonoma County Water Agency (SCWA) initiated a 4-month pilot study in conjunction withthe California Energy Commission to evaluate the effectiveness of microfiltration (MF) andreverse-osmosis (RO) processes, in series, following tertiary wastewater filtration. Specifically,the study examined the extent of PPCP and EDC contamination of tertiary-treated wastewater atthe project site, and the removal of these compounds through the two membrane processes.Additionally, the study targeted the transition from dry weather flows to wet weather flows in aneffort to expose the study to a concentration variable presented by these operational norms.The water quality objectives for the MF/RO permeate water were: to provide preliminaryindications of plant performance for the specific wastewater tested, such as operating pressures,cleaning frequencies, and membrane fluxes; to meet primary and secondary drinking waterregulations for compliance with California Title 22 water reuse standards; and, to removerepresentative PPCPs and EDCs to below detection limits. A suite of analytes was selected forthis project to represent a broad range of the most prominent PPCPs and EDCs in wastewater,based on scientific literature and the results from an initial characterization of the tertiary-treatedwastewater. Sampling throughout the study was conducted on the MF feed, MF filtrate, ROpermeate, and RO concentrate.The data collected throughout the study strongly indicate that the membranes tested can meet theobjectives set forth. Although biofouling caused some initial operational challenges, successfulprocess improvements indicated that biofouling issues could be minimized. The membranesotherwise ran at typical operating pressures and fluxes. All primary and most secondarydrinking water standards were met or exceeded under both wet- and dry-weather flows. Of the47 PPCPs and EDCs that were analyzed, about half were present in the tertiary-treatedwastewater effluent and the MF filtrate, including caffeine, nicotine, and estrogen. Only onecompound (the fire retardant TBEP) was present above detection limits in the RO permeate innaturally occurring influent concentrations. Under spiked influent concentrations, only NDMAand 1,4-Dioxane were present above detection limits in the RO permeate. This paper presentsresults and conclusions from the pilot study. Includes 20 references, tables, figure.

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Edition: Vol. - No. Published: 06/01/2006 Number of Pages: 19File Size: 1 file , 390 KB