Abstract: The filter has a spiral of, or parallel, spaced lengths of, double-ply material whose plies are seamed together along spaced, longitudinal seams to provide an array of side-by-side tubes. The filter support material is highly flexible and has a thickness not greater than 1 mm. Due to the tubular formation, the filter support has an uninterrupted filter zone of substantial area relative to the total area of the filter support; during filtration (when the filter support is under the pressure of the feed) the tube walls bulge out and the filter zone is restrained solely by tensile forces in the filter support itself. Substantial movement of the filter support is possible in the direction at right angles to its face when the pressures on either side of the filter support are equal.

Abstract: Dissolved selenium is removed from water by treatment in a reactor containing microbial biomass to cause the hexavalent selenium to be converted to forms of selenium which can be readily removed from the water, and causing or allowing the removable forms of selenium to be removed from the water. Examples of removable forms of selenium include volatile organic selenium compounds, volatile inorganic selenium compounds, elemental selenium, entrainable organically-complexed selenium compounds, entrainable tetravalent selenium compounds, and entrainable bivalent selenium compounds. The volatile selenium compounds can be removed and recovered as a gas, while the entrainable forms of selenium can be entrained by larger particles and separated off, for example by filtration.