Notice of RetractionResearch on Facilitation of Biodegradation of Azo Dye Wastewater by Bioelectrochemical Technology

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Active brilliant red X-3B is a kind of azo dye which is difficult to biodegrade. The wastewater with azo dye is of chromaticity depth, high content of organic compounds, water quality changing great, and seriously impacts environment. Bioelectrochemical hydrolysis coupled with biological contact oxidation (BEH-BCO) was used to treat azo dye active brilliant red X-3B simulation wastewater. In this experiment, synergy of micro-electrolysis and biological hydrolysis was used to improve the efficiency of hydrolysis reactor, and then improve the biodegradation of azo dye wastewater. In the experiment, the HRT of Hydrolysis reactor kept running 12h, and the HRT of biological contact oxidation reactor 7.95h. The electric current densities used in the experiment were 0.024, 0.048, 0.071mA/cm². This experiment was compared with the biological hydrolysis and biological contact oxidation (BH-BCO), the single biological treatment. Experiment results showed that, the removal effect of active brilliant red X-3B by bioelectrochemical technology was very good in heavy dye mass concentration in raw water (concentration was 50mg/L); and in the range of current density used in test, the treatment effect was increased with the increase of electric current density; when electric current density was 0.071mA/cm², the average removal ratio of dye mass concentration, colority, COD_Cr, and NH₃-N reached 98.77%, 91.39%, 69.98%, and 90.41% by bioelectrochemical technology respectively, and 9.65%, 1- .21%, 31.32%, and 85.69% respectively by the single biological method. There are some reasons for the results. The first reason is that the dye mass concentration of wastewater in raw water was too high, single biological hydrolysis was difficult m. The second reason is that, from the measure results of oxidation reduction potential, the hydrolysis reactor was in anaerobic condition in the experimental process, which produced inhibitory environment to bact- ria. The analysis of UV-visible absorption spectrum of the influent and effluent from each reactor indicated that the molecular structure of active brilliant red X-3B was destroyed by bioelectrochemical technology and turned into readily biodegradable small molecular organic compound, but it changed little by biological treatment. The measure results of redox potential showed that, the redox potential of mixed liquor in BEH was about -200mV, which is within the range of azo compound redox required standards (-180mV~-430mV); the redox potential of mixed liquor in BH was about -152mV, which is not in the required range, and is also not in the range of hydrolysis reactor working normally (about OmV). The results of measured azoreductase activity show that the azoreductase activity of the single biological hydrolysis was 1.68 mg/L·h, the azoreductase activity of bioelectrochemical hydrolysis was 55.33 mg/L·h. In a word, bioelectrochemical technology could promote the activity of hydrolysis microbe greatly, and obviously improve the decolorization effect of active brilliant red X-3B wastwater. It plays a great role in promoting biodegradation of azo dye wastewater.