Study On Reactor’s Performance And Bacterial Colony Analysis Of Integrated Bioelectrochemical-anammox System For Simultaneous Nitrogen Treatment And Bioenergy Production

Anammox is a novel and efficient process of removing nitrogen pollutant by directly converting ammonium and nitrite into gaseous N2 and nitrate in one step.It has lots of merits such as high nitrogen removal rate and nitrogen load,low oxygen consumption and energy waste,as well as strong resistance to massive nitrogen concentration.BES is a promising device which can simultaneously deal with pollutants and generate renewable electricity power.It is meaningful and valuable to combine Anammox with BES.This integrated system could effectively utilize the chemical energy in ammonia or nitrite and make contribution to reduce the emission amount of green gas.In this study,Anammox process was successfully coupled in the anode or cathode chamber of dual-chamber MFC reactors.The integrated systems could afford influent with high nitrogen content and their nitrogen removal performance were obviously improved.All the reactors could attain a satisfying removal rate of ammonia,nitrite and total nitrogen that more than 99%,94% and 85% respectively.The mechanism of nitrogen removal was considered as a synergistic effect of Anammox and BED process,which enhanced the removal rate of total nitrogen while comparing to conventional Anammox technology.Especially,as EAB was inculcated in anode chamber,the electricity generation performance of cathodic-integrated-Anammox-MFC reactor was obviously strengthened.It owned a maximal voltage output of 502.2 mV and a power density of 240.2 mW/m2,and an electrical period of 2900 minutes.Experiments were designed to investigate the effect of electrode materials,pretreatments and concentration of anolyte or catholyte on performance of the cathodic integrated Anammox-MFC.Results showed that an optimum condition would be reached while using graphite felt as anode electrode,carbon cloth as catholic electrode,and applying SDBS to pretreat the materials.When the content of acetate in anolyte increased,the maximum voltage output was not successfully risen,but the period was remarkably extended.In certain range,along with the nitrogen content in catholyte increased,the reactors’ performance of simultaneous nitrogen removal and electricity production would be better.And using the influent of ammonia of 400 mg/L and nitrite of 528mg/L met the best performance.However,while nitrogen content was excessive,MFC performance was terribly weakened owing to the inhibition effect of bacterial activity.Moreover,after the reactors operated over 3 months,both the ADB in anode chamber and the AnAOB in cathode chamber were tested through HiSeq technology to analyse the alteration of microbial colony composition.Results revealed that in origin EAB,the dominant Order were Rhodocyclales,Aeromonadales,Bacteroidales and Pseudomonadales,which were all reported as exoelectrogenic organisms.After the integrated system operated,the functional Genus of electricity generation were Pseudomonas and Sphaerochaeta.When the concentration of acetate in anolyte was set as 0.01 mol/L,the relative abundance of Pseudomonas increased to 18.3%,which represented a high level of electrochemical activity.However,when the acetate concentration rose to 0.02 mol/L,the bacterial colony was much more complicated,which helped the colony stay stable under a high concentration of COD.The dominant Phylum of the origin AnAOB were Planctomycetes,Proteobacteria,Chloroflexi and Bacteroidetes.After the integrated system operated,the functional Genus of Anammox and BED was Candidatus Brocadia and Dok59 respectively.As the concentration of nitrate accumulating,the relative abundance of Dok59 developed,which facilitated the removal of nitrogen through BED process.However,when the nitrogen content in catholyte was excessive,the activity of functional bacteria was terribly harmed,which led to a low nitrogen removal and power production performance.