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i may' --- - r f Figure 3: Perspective View of Textile Filter Unit and System Textile filters have been configured in several different recirculating "modes," some of which optimize nitrogen reduction. A configuration that has produced excellent nitrogen removal is shown in Figure 5. Effluent quality from the system in the Lapine, Oregon, (see case study on following page) is indicative of the treatment quality achieved with this mode of operation. Textile Filter System Case Studies Burnett, Washington A textile filter system followed by a polishing sand filter was installed in November, 1998, at a single family home in Burnett as part of the National Onsite Demonstration Project(NODP) for the community of Burnett. This treatment system was configured (Figure 4) to meet Washington State's Treatment s Standard 1, which includes BOD and TSS less than I0 mg/L and fecal coliform count of les than 200 per 100 milliliters. A small polishing sand filter using a clean "mason"type sand(effective size =0.19 mm)was installed after the textile filter to ensure the system meets the fecal coliform requirement. Although the test results have shown the fecal requirement is being met by the textile filter itself, effluent from other textile filters have not produced this level of fecal removal. Weekly testing for eight weeks in the spring of 1999 produced the following results: Burnett, WA Flow BODS TSS TKN NO3-n TN FC gpd mg/L mg/L mg/L mg1L mg/L MPN/100 In, Textile Filter Effluent 130 3 1 3 16 19 3 Polishing Filter Effluent 130 3 2 2 12 14 3 In addition to the Burnett site, demonstration textile filter systems in Rhode Island, Minnesota, and Oregon have been installed with small polishing sand filters or sand-filled trenches to "disinfect"the final effluent instead of traditional methods such as chlorine, UV, or ozone. The polishing sand filters are more reliable, less energy intensive,and require far less maintenance than the traditional methods. Problems associated with traditional disinfection methods on small wastewater systems include NTP-FLT-TR0-ESB-HLB-1 20 Page 6