Influence of Operating Variables on Performance of Nanofiltration Membrane for Dye Removal from Synthetic Wastewater Using Response Surface Methodology

The textile industry is a water intensive industry that produces a large amount of highly colored wastewater that must be properly treated before disposal or reuse. In the present study, to verify the possibility of reusing textile wastewater with nanofilteration (NF), an attempt was made to treatment of synthetic reactive dye aqueous solution by commercial nanofiltration membrane. Experiments were conducted based on a central composite face-centered design and analyzed using response surface methodology. Dye concentration (10-50 mg/l), operating pressure (3-6 bar), and initial pH of the dye solution (3-9) were selected as the operating variables to analyze, optimize and model the process. The results showed that alkaline and acidic condition led to considerable increase in dye rejection and permeation flux that high quality of water could be recovered. This study clearly showed that response surface methodology was one of the suitable methods to optimize the operating conditions and maximize the dye removal. Also, the commercial NF membranes could be efficiently applied in the dye removal process in a one-stage process.