Colloidal Fouling of Membranes in Textile Waste Reuse

Recovery of Wastewater from a Textile Mill: Implications for Membrane Fouling

Funding Agency: Bureau of Reclamation, City of Harlingen, Gulf Coast Hazardous Substance Research Center

Principal Researchers: Rik Hovinga, Srinivas Veerapaneni, Diane Bailey

A research effort looking at the reuse of industrial wastewater from a bleach and textile mill in Harlingen, Texas, is focusing on the role of dyes and colloidal material in the fouling process. The City of Harlingen's Wastewater Treatment Plant #2 treats a flow of approximately 3 MGD using a combination of primary settling, trickling filters, biotowers, secondary clarification, and sand filtration.

Beginning in 1990, a facility for recovering treated wastewater effluent using reverse osmosis (RO) was brought on line. This 2 MGD facility produces high quality product water from the filtered wastewater which is used by a local textile bleach and dye plant. The textile plant requires water with low total dissolved solids (TDS) and organic carbon concentrations. The bleach and dye operations at the textile plant increase the concentrations of color and TDS. Originally the textile plant used only reactive dyes. However, recently indigo dyes have also been included in some of the textile processes.

The resulting industrial wastewater is returned to the wastewater plant and contains high concentrations of a mixture of dyes and a TDS concentration of approximately 2500. This water is treated by extended aeration, clarification, and chlorination before being dechlorinated and discharged into a tidal zone via the Arroyo Colorado. The industrial wastewater (resulting from the use of RO-treated product water) is biologically treated, clarified, blended with the RO concentrate before discharge. A greater demand for process water is anticipated and it has been proposed that this demand be met by treating the industrial wastewater which is currently being discharged after treatment. However, optimal treatment of the textile mill wastewater requires consideration of the fouling characteristics of materials in the wastewater compared with those in the current RO feed.

The ongoing effort is evaluating the tranport and fouling characteristics of colloidal materials in this reuse scenario.