Pilot-scale evaluation of nanofiltration and reverse osmosis for process reuse of segregated textile dyewash wastewater

Abstract

Abstract Segregated wastewaters from dyewash processes in a weaving industry were treated for decolorization, as well as the removal of chemical oxygen demand and salts using a pilot-scale membrane system. Nanofiltration (NF-270) and reverse osmosis (RO-XLE) membranes were evaluated under different operating modes namely batch concentrate-recycle mode and continuous mode without concentrate recycle. Activation energies of pure water permeation across the RO-XLE and NF270 membranes were measured to be 6.51 ± 0.53 kJ mol − 1 and 3.87 ± 0.24 kJ mol − 1 respectively. The average flux values of NF-270 and RO-XLE membranes were 51.0 ± 17.5 l m − 2 h − 1 and 27 ± 6.5 l m − 2 h − 1 in batch mode, respectively. The average flux values of membranes at continuous mode were 42 ± 6 l m − 2 h − 1 for NF-270 membrane and 26 ± 3 l m − 2 h − 1 for RO-XLE membrane. An empirical equation correlating the instantaneous flux to inlet COD, conductivity and color values were obtained using Statsoft STATISTICA 8.0. High COD, conductivity and color removal efficiencies were achieved demonstrating the applicability of membrane treatment for textile industry wastewaters. Hence, the highly polluted dyewash wastewater could be effectively treated by membranes to produce water for process reuse in the dyewashing process.