Process development for textile wastewater treatment towards zero liquid discharge: Integrating membrane separation process and advanced oxidation techniques

Abstract

A treatment process based on microfiltration followed by nanofiltration (MF-NF) is proposed for textile wastewater treatment. The NF concentrate is further treated by UV/H2O2, Fenton, and photo-Fenton processes. Results showed that the dye was efficiently retained by the MF membrane (>99.1%), which allowed its reuse. The MF-NF was able to reject 92% of the chemical oxygen demand (COD) and>98.5% of color. When the NF concentrate was treated by UV/H2O2, it was achieved a maximum COD removal of 63% in the condition C:H2O2 1:3 (molar ratio of COD and hydrogen peroxide) and pH 3. The Fenton process, optimized through response surface methodology, achieved 84.7% of COD removal, which increased when combined with UV irradiation (92.2%). An analysis of the NF permeate physicochemical quality and its treated concentrate suggested that it can be reused in the textile industry for different purposes as yarn washing-off and equipment’s washdown. The operating cost for MF-NF corresponded to 0.240 US$/m3 and, including the cost of NF concentrate treatment by photo-Fenton, 0.517 US$/m3, lower than currently practiced by the water distribution company. The system proposed for water reuse and NF concentrate treatment was able to increase the water recovery and decrease the environmental impacts that could be caused by the NF concentrate disposal.