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4 1 <br /> • Land area—The land area needed is significantly smaller than that for sand filters <br /> because loading rates are 5 to 30 times higher(typically, 15-30 gpolfO with peak flow <br /> capacity/factor(PF) of 2.0 or greater, based on residential effluent quality as <br /> described in Tables 1 and 2). Thus, the footprint area for a textile filter serving a <br /> typical four-bedroom single-family home is now only about 20 square feet. If the <br /> textile filter is positioned over the processing tank,virtually no additional area is <br /> required. <br /> • Media quality and availability—The manufactured textile medium ensures <br /> consistent quality and availability. <br /> • Installation quality—Lightweight textile medium(4.0 lb/ft3) and small filter size <br /> make pre-manufactured treatment units practical, eliminating onsite construction and <br /> reducing installation time, labor, and construction errors. These characteristics make <br /> textile systems ideal for cost-saving self-help programs and particularly suited for <br /> difficult-to-access and remotely located sites. <br /> I <br /> • Serviceability—Special configurations allow for ease of maintenance and cleaning <br /> without expensive or large excavation equipment, or the need for replacing the <br /> medium. A single-family residential filter can now be cleaned and serviced in as <br /> little as an hour. <br /> The initial research on the textile medium began with small chips or"coupons" with a complex fiber <br /> structure, which offered an extremely large surface area for biomass attachment. Later research has <br /> been focused on developing textile filter blends and configurations that address early packed bed filter <br /> issues regarding ease of serviceability without sacrificing equivalent performance. <br /> Porosity, attached growth surface area, and water-holding capacity contribute to the textile media's <br /> treatment performance. <br /> • Porosity_�The porosity of the textile media is several times greater than that of sand, gravelP <br /> and other particle-type mediums. The more porous the medium,the greater its hydraulic <br /> conductivity, the greater its air space (which enhances the capacity of passively ventilated <br /> systems and free air movement), and the greater its capacity for the accumulation of solids and # <br /> biomass development., <br /> • Surface area—Textile media can be blended with a variety of fibers to achieve relatively large <br /> total surface area per unit volume (ft240). In current media blends, the typical attached-growth <br /> surface area is 4-8 times greater than recirculating filter media. Expanding the biomass growth <br /> area provides a greater surface potential for air and effluent to interface and come in contact with <br /> the biomass. <br /> • Water-holding capacity—;The water-holding capacity of textile media also varies considerably <br /> depending on the media density,type of material, and blend of fibers. The water-holding <br /> capacity in textile media is also several times greater than expected in the sands and gravels used <br /> in filters. Water-holding capacity performs a key function in the treatment process. Together <br /> with the programmed dosing time and frequency, it governs the effluent retention time within the <br /> NTP-FLT-TRS-1 <br /> Rm 1.1.11/02 <br /> Page 4 of 12 <br /> r <br />