Characteristics And Mechanism Of Simultaneous Nitrification And Denitrification Microbial Fuel Cell

Ammonium is the common pollutant in the process of sewage treatment.As a new biological nitrogen removal technology,nitrogen removal microbial fuel cell(MFC)has basically eliminated the disadvantages of traditional biological nitrogen removal process and become a popular process for ammonia removal from wastewater.In order to isolate,purify and screen heterotrophic nitrification aerobic denitrification bacteria(HN-ADM)from aerobic sludge and return sludge,and construct synchronous nitrification denitrification MFC(SND-MFC)with high efficiency of nitrogen removal and electricity generation,the denitrification efficiency of different electrode materials(carbon felt,carbon plate,carbon paper and graphene film)and electrode spacing(1cm,2cm,3cm,4cm)in the initial stage of SND-MFC was further determined In addition,the effects of pH,temperature and initial ammonium on the performance of SND-MFC reactor were analyzed.The main results are as follows。(1)Several strains of HN-ADMs were isolated from aerobic activated sludge in aeration tank of sewage treatment plant.Through species identification,HN-ADMs were all Pseudomonas.Finally,the strain with the best denitrification and electricity production performance was obtained.(2)Psedusomonas.HY01 was inoculated into SND-MFC device by pure strain inoculation and the data showed that it could effectively remove ammonium,nitrate nitrogen and COD in the simulated wastewater within 21 days,with an average ammonium removal rate of 80.67±0.63%,and the effluent nitrate nitrogen continued to decline,with an average COD removal rate of 52.60±1.15%.At the same time,the reactor could produce electricity continuously and stably,with a maximum power density of 142.14mW/m3 and a maximum coulomb efficiency(CE)of 5.93±0.13%SND and simultaneous denitrification and electricity generation were realized in SNDMFC.(3)Among the four kinds of SND-MFC electrode materials,graphene film has the best comprehensive power generation performance,with the maximum ammonium removal rate of 92.31%and the maximum power density of 134.28 mW/m3.In addition,4cm as the optimal electrode spacing of SND-MFC has the highest power generation efficiency,and the maximum power density of SND-MFC reactor was 151.84mW/m3.(4)SND-MFC reactor is suitable for denitrification and electricity generation in neutral environment.When pH=7.0± 0.1,SND-MFC has the strongest denitrification and electricity generation performance,with an average denitrification efficiency of 89.91 ± 0.13%and a power density of 122.61 mW/m3 within 7 days.30℃ is the optimal temperature for SND-MFC to remove nitrogen efficiently.Psedusomonas.HY01 achieved good nitrogen removal effect in SND-MFC with an average nitrogen removal efficiency of 91.02±0.43%.The power generation performance increased continuously with time,and the maximum power density was 135.17 mW/m3.Meanwhile,the data showed that SND-MFC could also effectively remove nitrogen and generate electricity at low temperature(15 ℃).SND-MFC is suitable for the treatment of low and medium concentration ammonium wastewater.The average ammonium removal rate was more than 85%,and the maximum power density was 136.41mW/m3.