Recovery of water from textile dyeing using membrane filtration processes

Abstract

The aim of the work was to purify model textile wastewater (MTW) using a two-stage membrane filtration process comprising nanofiltration (NF) and reverse osmosis (RO). For this purpose, a nanofiltration membrane TFC-SR3 (KOCH) and reverse osmosis membrane AG (GE Osmonics) were used. Each model wastewater contained a selected surfactant. The greatest decrease in flux in the initial phase of the process occurred for the detergents based on fatty-acid condensation products. An evident decrease in performance was observed with polysiloxane-based surfactants. No fouling effect and high flux values were observed for the wastewater containing a nonionic surfactant based on fatty alcohol ethoxylates. During RO, a significantly higher flux and lower resistance were observed for the feed that originally contained the anionic agent. For the MTW containing the nonionic surfactant, the conductivity reduction ranged from 84% to 92% depending on the concentrate ratio at the consecutive stages of RO. After treatment, the purified wastewater was reused in the process of dyeing cellulose fibers with reactive dyes. The research confirmed that textiles dyed with the use of RO filtrates did not differ in quality of dyeing from those dyed in pure deionized water.