Keywords: dye removal, nanofiltration, reverse osmosis, retention, turbulent promoter, dyeing effluent, tanneries, membrane separation, wastewater treatment, flux enhancement
Treatment of dyeing effluent from tannery using membrane separation processes
Treatment of a dyeing bath of a tannery was carried out using a hybrid membrane-based separation scheme consisting of Nanofiltration (NF) followed by Reverse Osmosis (RO). Experiments were conducted using a cross-flow cell in continuous mode. The performance criteria of the separation scheme were evaluated in terms of dye concentration, Chemical Oxygen Demand (COD), Biological Oxygen Demand (BOD), Total Dissolved Solids (TDS), Total Solids (TS), pH, Cl− concentration, chromium (III) concentration, etc. Effects of different operating conditions, namely operating pressure and cross-flow velocity, on the system performance were investigated. Complete retention of dye was obtained in NF step itself. NF-treated solution was further subjected to RO to bring down the BOD and COD values of the treated effluent below the permissible level. Possibility of flux enhancement using turbulent promoter in laminar flow regime and imposing turbulent flow regime itself was also investigated both in NF as well as RO.