Pilot-scale ceramic ultrafiltration/nanofiltration membrane system application for caustic recovery and reuse in...

For sustainable water management, the treatment and reuse of industrial wastewater are becoming increasingly important. There have been many studies on color removal, especially from textile wastewater. However, there are deficiencies in the literature regarding highly alkaline caustic recovery and reuse in the plant. For this reason, this study examines caustic-containing textile wastewater treatment and the reuse potential of the obtained caustic chemicals with a pilot-scale ceramic membrane system. During operations, only an ultrafiltration membrane, a nanofiltration membrane, and combined ultrafiltration + nanofiltration membranes were put to use. Chemical oxygen demand, total hardness, color, total organic carbon, sodium ion concentration, and pH tests were applied to samples, and temperature and flux were recorded throughout all operations. The obtained results showed that for ultrafiltration + nanofiltration cycles, the overall average removal efficiencies were 67, 71, 42, and 92% for total organic carbon, chemical oxygen demand, total hardness, and color respectively. For only ultrafiltration cycles, the overall average removal efficiencies were 22, 36, 25, and 63% for total organic carbon, chemical oxygen demand, total hardness, and color, respectively. Sodium values in the input wastewater were around 12 mg/L on average, and nanofiltration membrane output values changed to between 7 and 11 mg/L. Based on the sodium concentration differences between inflow and outflow samples, the permeate of ceramic membrane systems has potential for reuse in facilities.