The report describes a demonstration of multimedia filtration as an effective tertiary treatment for biologically treated textile wastewaters from two adjacent plants involved in dyeing and finishing fabrics of man-made fibers. Adding alum, polyelectrolytes, and powdered activated carbon to the treated wastewater, just ahead of multimedia filtration, reduced criteria pollutants and produced effluent meeting NPDES requirements. Treated wastewater was further treated to provide colorless effluent satisfactory for reuse in dyeing man-made fibers in a pilot plant consisting of a coagulation/settling/filtration unit followed by a five-column train comprised of a sand filter, organic scavenging resin, granular activated carbon, and cation and anion exchange resins. This water was satisfactory for dyeing a full range of shades, including white and pastel colors on man-made fiber fabrics. Color-fastness was equivalent to that of standard control dyeings. Tramp color scavenging ability of different man-made fibers was found to be quite variable. Essentially colorless effluent is required for reuse in dyeing white or pastel shades on nylon and triacetate fabrics. Although technical feasibility of further treating biologically treated effluent to permit its use in critical dyeing and finishing operations was demonstrated, the economics of commercial application are not attractive.

Grant no. S801211, program element no. 1B2036. April 1978.