Electronically Stimulated Anaerobic-Aerobic Continuous Flow Reactor For Enhanced Removal Of Azo Dye Wastewater

Printing and dyeing wastewater is a kind of industrial wastewater which is widely used in printing and dyeing textile industry with high pollution,high color,difficult to remove and so on,among which azo dyes occupy a large proportion.Since the conventional aerobic activated sludge can not break the azo bond,and the anaerobic biological treatment process is often due to the toxicity and difficult degradation of azo dyes,resulting in low efficiency and long process cycle,so how to economically remove azo Dye wastewater has always been a hot and difficult task for researchers.Traditional physical chemistry and biotechnology can partially remove the waste water,but because of its high cost,poor handling of the shortcomings often can not meet the actual needs.On the other hand,with the development of bioelectrochemical systems(BESs),more and more studies have shown great potential and application prospects for the removal of printing and dyeing wastewater,especially azo dyes.In this paper,a typical azo dye,alizarin yellow R(AYR),was selected as the target contaminant.First,the traditional anaerobic-aerobic process was used to study the effect of the treatment.The removal efficiency and effluent concentration of the effluent and AYR under the different operating parameters were observed by changing the hydraulic retention time and the reflux rate of the nitrification solution.With the increase of residence time and reflux ratio,the effect of the reactor on the mixed polluted wastewater was improved.According to the multivariate comprehensive analysis and response surface method and considering the economic factors,the residence time was 9h And the reflux rate of nitrification solution is 300%,the optimal experimental parameters are the best.Under these conditions,the optimal removal rates of COD,nitrate nitrogen,ammonia nitrogen and AYR were 86.5%,66.5%,58% and 45%,respectively,under the control of other variables.Anaerobic-aerobic process on the removal of AYR effect needs to be further strengthened.Under the optimum A/O process operating conditions,an electrode is implanted in the anaerobic stage of the reactor and connected to an external power supply to provide a constant voltage,providing an additional electron donor through the cathode constant potential for AYR and nitrate nitrogen,The effect of different electrode materials(carbon brush and new fold electrode),electrode position and different voltage on the removal efficiency of AYR and nitrate.The results showed that the average removal rate of AYR reached 92.0% after implantation,which was more than 2 times higher than that of nonimplanted,and the removal ability of AYR was improved in different degrees COD,nitrate nitrogen,ammonia nitrogen and AYR removal rate increased by 2%,6%,22% and 45%,respectively).The results show that the average removal rate of the electrode in the anaerobic section is 5% higher than that in the pre-deviation position.The effect of the new type of fold electrode is better than that of the ordinary carbon brush electrode,Ammonia nitrogen and AYR removal rates were increased by 1%,2%,6% and 20%,respectively.When the voltage increases from 0.5-1.5V,the removal rate of the pollutants is gradually increased,and the voltage is the most energy efficient when the voltage is 1.3V.At this time,the removal rate of each index is lower than that of the electrode Respectively,increased by 2%,6%,24%,47%,effluent AYR concentration can reach the textile dyeing and finishing industry wastewater pollutant discharge standards.Analysis of bacterial community structure,anaerobic group found that azo dyes and nitrate nitrogen reduction as the dominant functional species,such as Acinetobacter,Longilinea,Levilinea and Dechloromona,considered mainly involved in the AYR reduction decolorization and denitrification reaction,Nitrogen and AYR removal ability significantly increased the experimental results are consistent.The average electricity consumption in the electrode was 260.15 mmol,and the enhanced removal of nitrate and AYR consumed 63.75% and 18.02%,respectively.Among them,55.19% of the electrons were removed from the AYR,and the effect of the applied voltage was more obvious The(PPD)and 5-aminosalicylic acid(5-ASA)were detected in the anaerobic effluent,and both PDP and 5-ASA were detected in the aerobic effluent,Indicating that it is further decomposed,and aerobic enrichment of a large number of PDP and 5-ASA decomposition bacteria,such as Rhodocyclus and Clostridium,further verify this point.At the same time,Propionispira,Rhodocyclus and Clostridium and other functional bacteria can make extensive use of COD and nitration in aerobic conditions to remove ammonia nitrogen,through the synergistic effect of the whole system to achieve AYR and simultaneous removal of COD and inorganic nitrogen.As the anaerobic aerobic process in sewage treatment is very common,and the wrinkle electrode as electrode material is cheap and easy to scale production,in the case of lower voltage consumption of electricity can be significantly lower technology to remove the process of azo dye wastewater removal Ability,in the traditional anaerobic process to strengthen the conversion is also more convenient,this study for the removal of dye wastewater to provide a new way of thinking.