Comparison of three NF membranes for the reuse of secondary textile effluents

Textile industry processes (dyeing, bleaching, printing and finishing) require a high-water consumption generating high amounts of wastewater. According to the literature, typically 200 and 500 L of water are needed to produce 1 kg of finished product [1]. This fact in combination with the current water scarcity makes necessary textile wastewater reuse. In this work, nanofiltration of biologically treated textile wastewater has been evaluated testing three nanofiltration membranes. It was studied that the influence of different volume concentration factors (VCF) on the permeate flux and salts and COD rejections. Nanofiltration experiments were carried out in a laboratory plant equipped with a pressure vessel containing one spiral wounded membrane element. The membranes tested were Ds-5 DK and DURASLICK from General Electric and Fluid System† TFC† SR† 2 from KMS. For all membranes, the COD values in the permeate were negligible and flux reduction was not severe even for the maximum operating VCF (3). According to the permeate characteristics the main use of the treated water is for machinery washing processes and print implements.

According to the permeate characteristics (a conductivity value between 2 and 3 mS cm(1 in combination with a negligible COD), the main use of the treated water is for machinery washing processes and print implements. In Colortex, this water usage means around 35% of the total water consumption. Comparing the three tested membranes, it seems that DURASLICK membrane be the most appropriate membrane for this particular application, since it yielded the highest permeate flux during the tests. However, due to the small differences between the flux values (only 14%) long term experiments should be carried out to confirm the differences between the membranes tested.