| The tail water discharge of municipal sewage treatment plant is becoming an important source of pollution.It is urgent to improve the discharge standards of nitrogen and phosphorus to control the eutrophication of water and guarantee the quality of water environment.In this study,on the basis of the traditional A2O process improvement,the microbial electrochemical system such as microbial fuel cell（MFC）and microbial electrolysis cell（MEC）was coupled to build two sets of microbiological nitrogen removal processes:A2O-MFC-MEC and A2O-MFC-MEWE.The rapid start-up methods and the effect of removing carbon and nitrogen during stable operation period for the two processes were under review.Nitrogen removal efficiency and fluorescence analysis of different chamber under optimum conditions were investigated.High throughput of the system microorganism population was analysed.In addition,the effects of key parameters such as weak electrical strength,HRT and internal reflux ratio on A2O-MFC-MEC denitrification were also discussed.The operation results showed that the aerobic and anaerobic sludge was inoculated with early domestication and cultivation.The pH was 7.0-8.0,the temperature was room temperature and the load was gradually increased.The removal rate of chemical oxygen demand（COD）and ammonia nitrogen（NH4+-N）in the anaerobic pond remained stable at 50%and 40%.MFC electrode material was made of manganese ore carbon felt electrode coated by coating method.When the distance between cathode and anode was 2.0cm,the maximum power density of MFC was 48.4mW/m2.While the MEC stimulation voltage was 0.3V,and the removal rate of COD and NH4+-N in the two process reached 45%and 35%respectively.The results of comparison and analysis of nitrogen removal efficiency of two process showed that the total nitrogen removal rate of A2O-MFC-MEC was 23%higher than that of A2O-MFC-MEWE process at the stable operation stage.Therefore,the A2O-MFC-MEC reactor was used as the main object for the optimization of the process key parameters.In the optimization stage of the key parameters,the TN removal rate of the system was the highest and 63%when the MFC was 500mV and the 300mV was supplied to MEC.When the HRT was 24h,the power generation performance of the system was the best and the TN removal rate was 46%.When the internal reflux ratio was 200%,the TN removal rate of the system was the highest and was 69.5%.By analyzing the nitrogen removal efficiency of the coupling system and the common system,it was found that the TN treatment rate of the coupled process was 23.9%higher than that of the A2O process.The TN removal rates of the anaerobic pool,the anoxic pool 1 and the oxygen pool 2 are increased by 11.4%,5.9%and 7.6%,respectively.The optimal working condition of the coupling system for the treatment of sewage water was that the HRT,the weak electric intensity and internal reflux ratio was 24h,500mV for MFC,300mV for MEC,200%,respectively.The A2O-MFC-MEC system had a very obvious selection effect on the species of microbes in the normal operation stage,so that the microbial flora with different functions can become in the same ecosystem and jointly promote the treatment of urban sewage TN and reduce the emission concentration.The results of microbial high-throughput sequencing showed that the anaerobic and anoxic pools in the electrochemical system enriched a large number of electricity producing and denitrifying bacteria populations.The dominant microbial communities in the system were Proteobacteria,Firmicutes and Acidobacteria,and the dominant denitrifying microbial communities were Rhodanbacter and Bacillu.The results of the three-dimensional fluorescence spectrum analysis of the effluent from each chamber of the coupling system showed that the organic substances such as protein were significantly improved under the action of weak electricity. |
PDF Full Text Request