Study On Enhanced Decolorization Of Dye Wastewater Based On Bio-electrochemical Systems

With the rapid development of industry, wastewater from printing and dyeing industries has caused serious water pollutions. Once being discharged into aquatic environment, this kind of wastewater not only affects the visual appearance, but also endangers fish and other water lives. Especially those azo dyes with carcinogenic and mutagenic properties are dangerous to our lives. Since the dyes wastewater has poor biodegradability, physical adsorption and membrane separation methods are usually adopted, however, it suffers from a higher recycling expense and membrane costs. As a result, seeking an effective means of disposing of dyes wastewater becomes very important. In this study, the electricity produced from microbial fuel cells was used to strengthen an azo dye(methyl orange, MO) electrochemical decolorization, which is of great significance for the further treatment of dyes wastewater.Herein a novel aerated electrochemical reactor with utilization of microbial fuel cells(MFCs) as renewable power sources was proposed for effective degradation of azo dyes decolorization. Aeration electrolytic reactor was composed of two electrodes,in which air was sparged near the cathode. By altering electrolyte concentration and other factors in the reactor, the optimal removal efficiency was achieved, after which the mechanism of the reaction process was explored. Afterwards, carbon and iron were added to the aeration electrolytic reactor to further strengthen decolorization efficiency and response surface methodology(RSM) was conducted to optimized four factors including initial pH, ratio of iron to carbon, aeration, initial dye concentration.The results showed that:(1) A degradation efficiency of 90.4% for MO was achieved after 360 min electrolysis with its initial concentration of 50 mg/L, initial pH of 3.0, electrolyte(Na2SO4) concentration of 0.01 M and carbon felts selected as electrodes.(2) Studies of operating factors indicated that: using carbon felts as electrodes performed better; A higher initial dye concentration and higher pH values resulted in a relatively lower decolorization efficiency; The concentration of Na2SO4 had little impact on decolorization efficiency.(3) H2O2 concentration determination showed that strong oxidants were responsible for MO degradation; UV-vis spectraevolution during the electrochemical degradation of MO and GC-MS result further indicated that effect decolorization and mineralization were finished.(4) During RSM experiment, with the target of the maximum decolorization efficiency, we got the optimal results in the condition of initial pH of 3.05, ratio of iron to carbon of 0.66,flow rate of 5.80 L/min and initial dye concentration of 54.32 mg/L.By investing factors and mechanism study, this work reveals that applying the bioelectricity generated from MFCs to electrochemical process is promising and cost-effective for dye wastewater further treatment and it provides a reliable theoretical and experimental support for the practical application.