Treatment of textile plant effluent by nanofiltration and/or reverse osmosis for water reuse

This work concerns the treatment of textile plant effluent after conventional biological processing. The objective was a feasibility study of the combination of physicochemical treatment with nanofiltration (NF) and/or reverse osmosis (RO) for water reuse. In fact, dead-end filtration by microfiltration (MF), ultrafiltration (UF), NF and RO tests showed that a primary physicochemical treatment (coagulation/flocculation) was necessary to limit membrane fouling. Two coagulants (organic polyelectrolyte and/or ferric chloride) were tested and compared by carrying out jar-tests using different chemical concentrations at pH 6.8. Then, NF and/or RO experiments were performed and investigated at different operating pressures. Results showed that NF allowed the higher flow rate, 90 L.h−1.m−2 at 18.5 bar transmembrane pressure. Moreover, the permeate quality obtained in this condition was similar to the RO. Conductivity, absorbance at 490 nm and the dissolved organic carbon value of the NF permeates were lower than 390 μS.cm−1, 0 and 2 mg.L−1 of C, respectively. The percent production rate increased with the transmembrane pressure. NF performed at 18.5 bar transmembrane pressure allowed a higher yield (22.6%) than RO (18.3%).