Performance evaluation of two stage nanofiltration for treatment of textile effluent containing reactive dyes

Abstract

Two stage nanofiltration was found to be adequate for treatment of a real life textile effluent so that the final treated water confirmed the quality parameters for reuse or disposal to surface water. Three anionic reactive dyes, acidic yellow, cibacron red, cibacron black and basic blue, a cationic one constitute the dye profile in the effluent. Effects of operating conditions i.e., transmembrane pressure and cross flow rate on system performance in terms of dye rejection, salt recovery, total dissolved solids and chemical oxygen demand were investigated. Anti-fouling characteristics were evaluated by flux recovery and flux decline ratio. 88 percent flux recovery was achieved in first stage. Almost complete flux recovery was attained in the second stage confirming long membrane life. Dye separation was mainly by size exclusion facilitated by charge–charge interaction. Finally treated effluent confirms the water quality parameters of total dissolved solids and chemical oxygen demand for safe disposal to surface.