Study On Operation Characteristics And Enhanced Nitrogen Removal Of MFC Coupled MAMBR

In this study,microbial fuel cells（MFC）and membrane bioreactors（MBR）were used to complement the advantages of pollutant removal and energy consumption,and membrane aeration was used to replace the traditional MBR aeration method,and a novel integrated microbial fuel cell-membrane aerated membrane bioreactor（MFC-MAMBR）was constructed,and the autocatalytic denitrification sludge with high anaerobic ammonium oxidation（Anammox）activity was inoculated at the cathode of the MFC-MAMBR.It provides a new idea and theoretical basis for the long-term problem of insufficient carbon source for the traditional biological nitrogen removal of wastewater.It also provides a new coupling method and application prospect for the microbial fuel cell coupled membrane bioreactor.The main research results include the following two parts:Part Ⅰ:Anammox active autotrophic denitrification sludge enrichment cultureThe anaerobic granular sludge was inoculated to the ESGB reactor,and the simulated inorganic artificial wastewater was used as the influent.After 200 days of operation,the Anammox-EGSB reactor has a maximum TN removal rate of 89.0%and a volumetric nitrogen removal load of 0.6 kg-N/（m3·d）.During the start-up process,the reactor mainly experienced four stages:activity lag phase,activity display period,load increase period and activity promotion period.During the culture process,combined with DO,pH and sludge apparent characteristics in the system,the following strategies were adopted to promote the rapid enrichment of anaerobic ammonium oxidizing bacteria:（1）increase the dosage of NaHCO₃ to stabilize the pH;（2）increase the influent nitrogen matrix concentration to optimize the sludge particle state;（3）strictly expose nitrogen to remove oxygen before the new particulate sludge has not formed,and avoid excessive nitrogen aeration resulting in pH increase after particle formation.Microbiological analysis showed that the AnAOB of the genus Brocadia of Planctomycetes was detected in mature sludge,and the abundance was 25.4%,and a small amount of denitrifying genus Denittrasoma was detected,and the abundance was 2.0%.Sludge is a microbial ecosystem in which anaerobic ammonium oxidizing bacteria work synergistically with other bacteria（such as nitrifying bacteria,denitrifying bacteria,etc.）,and the color is dark brown with a large amount of blood red particles.Part Ⅱ:Study on the operating characteristics and pollutant removal effects of MFC-MAMBRThe cultured mature Anammox-EGSB sludge was inoculated to the MFC-MAMBR cathode,and after the voltage was stabilized,the effect of the cathode DO on the operating characteristics of the MFC-MAMBR was investigated.The results showed that the MFC-MAMBR had the best pollutant removal efficiency when the DO concentration was 0.2⁰.6mg/L.The removal rates of COD and TN reached 86.16%and 56.03%,respectively;the aeration intensity corresponding to the DO condition was 75-150 kPa.A comparative study with an open circuit device found that the intervention of the electrochemical system enhanced the removal of contaminants from the two aspects of providing an electron transfer path and microbial electrical stimulation.Under the optimal DO condition,it was found that the anode of the MFC-MAMBR is the main site of COD metabolism,and the cathode is the main site for autotrophic nitrogen removal through the analysis of the spatial removal characteristics of the pollutants and the microbial community structure and spatial distribution.The microbial community inoculated into the cathode sludge of MFC-MAMBR device changed greatly.The original dominant Firmicutes and Atribacteria were transformed into the community structure of the dominant species with Proteobacteria,Bacteroidetes and Chloroflexi.Candidatus Brocadia is the main genus of Anammox bacteria in the MFC-MAMBR,mainly distributed in the cathode electrode and suspended sludge.Ammonia-oxidizing bacteria（AOB）mainly come from Nitrosomonadaceae,and a small amount of nitrite oxidizing bacteria（NOB）is detected from Nitrospira,and AOB and NOB are mainly distributed on the surface of membrane aeration tube.In terms of denitrifying bacteria（DNB）,the most abundant DNB is derived from Pseudomonas,which is mainly distributed on the cathode electrode.