Effect of operating conditions on color and anions removal from textile industrial effluent using membrane distillation system

Abstract

One of the main pollution from textile wastewater is the dyeing wastewater containing color and organic matters. To develop wastewater treatment systems and to reuse the water are still challenged because of the scarcity of water in the world. Among the treatment methods of textile wastewater, membrane distillation was used as the concept of this research. The focus points of the direct contact membrane distillation system are the membrane characteristics, operating parameters (temperature and flow rate) and treatment efficiency. The synthetic dye wastewater (reactive black-5 and reactive blue-19) and real textile effluent were used as the feed wastewater. In this research, SEM imaging, the contact angle, the zeta potential and the porosity of the membrane were taken to investigate the membrane characteristics and the fouling conditions. The contact angle (greater than 90 degrees) showed that the material still had the hydrophobic properties after treatment and the zeta potential showed also the anions property of the material.

In terms of operating parameters, the feed temperature and flow rate can significantly affect the permeate flux. The increased feed temperature (40 °C,50°C, and 60°C) can also increase the permeate flux up to about 4 times at 60°C, compared to that of 40°C. The increased cross-flow velocity can give the results of increased permeate flux (up to 80% and 50% at 0.15 m/s) more than 0.05 m/s. The flux of real wastewater is about 48% lesser than the synthetic wastewater under the same operating parameters. The color removal efficiency is in the range of 96% to 98%, although the feed color concentrations were changed. Another parameter analysis; pH, conductivity, anions, and TOC were also taken in this study. As with the collected results, the permeate water parameters are lower than the Industrial Effluent Standards B.E. 2560 by the Ministry of Industry. To use in the site and implement, the direct contact membrane distillation system should be considered with the renewable energy, the optimization of membrane preparations (spacers, fouling conditions and the novel membrane material) and the process conditions.