Membrane filtration of textile dyehouse wastewater for technological water reuse

Abstract

Polish textile industry demands big amounts of water and produces wastewater having high load of contaminants. The continued increase in the costs of chemicals, energy and water makes their recovery more important today than it was years ago when separation techniques by membrane filtration were first introduced to the textile industry. The aim of introducing membrane filtration is not only to reduce water consumption and wastewater streams. Membrane filtration also reduces the consumption of energy as the warm water can be recovered. While the filtration techniques applied for textile wastewater treatment and water recovery have been used at only few installations, these installations have been reported as successful and have been able to save enough to repay the recovery process in one to two years [1]. The paper describes the results of research works and implementation project concerning cleaner technology and water reuse in textile dyehouse. The goal of the research was application of membrane filtration to reuse water after dyeing of cotton and polyester fabrics. The Textile Research Institute in Lodz, Poland, together with the Danish partners, the Technical University of Denmark, the Institute for Product Development and RINSE has carried out this research. The research was sponsored by Danish Environmental Protection Agency DEPA. Membrane filtration has been tested in lab and pilot scale. The experiments were done with selected two membranes for nanofiltration and one for reverse osmosis. All membranes were manufactured by Desalination Systems and made of proprietary polysulphone. The lab tests investigated membrane performance using chemicals selected from real process wastewater. The pilot scale tests were done to prove membrane performance in industrial use and determine dimensioning parameters for full-scale system. The results of lab and pilot scale tests have shown that membranes can be used with the rinsing water from dyeing of cotton and polyester fabrics. As the result of the pilot scale tests two full scale systems were proposed: nanofiltration system producing permeate which can be used in limited technological processes and reverse osmosis system producing permeate of the same quality as technological water.