生物电化学系统中阳极氨氧化作用强化及亚硝酸盐累积特性

Enhancement of anode-dependent ammonium oxidation and nitrite accumulation characteristics in a bioelectrochemical system

微生物电化学氨氧化工艺是一种新型生物脱氮技术,可弥补短程硝化工艺在处理城镇生活污水时的缺陷.为了解其运行特性,以NH_(4)^(+)-N为唯一底物,分析双室生物电化学系统(BES)在不同外加阳极电势下的NH_(4)^(+)-N转化性能、氧化产物及其微生物学特征,并探究外加阳极电势对BES中阳极氨氧化作用及NO_(2)^(-)-N累积特性的影响.结果显示,将外加阳极电势由0.00提升至0.50 V,BES的启动进程加快,稳定运行后其阳极氨氧化作用的强度逐渐增加,系统的NH_(4)^(+)-N氧化效率(AOE)与NO_(2)^(-)-N累积效率(NiAE)随之提高;当外加阳极电势≥0.80 V时,BES中NH_(4)^(+)-N的氧化产物因工作电极表面的析氧反应转而以NO_(3)^(-)-N为主,阳极氨氧化作用因电势进一步升高至1.00 V而受到抑制,致使系统AOE下降.当外加阳极电势为0.50 V时,Nitrosomonas(40.05%)和Empodebacter(21.92%)是电活性氨氧化生物膜中的优势菌属,两者参与了BES中NH_(4)^(+)-N的氧化,此时系统中的阳极氨氧化作用得到强化,并可取得较佳的NH_(4)^(+)-N转化效果[AOE=89.48%(±2.22%)]高水平的NO_(2)^(-)-N累积量[NiAE=88.16%(±2.02%)].上述研究结果表明,通过调控阳极电势可在BES中培育出电活性氨氧化生物膜,此生物膜可通过阳极氨氧化作用将NH_(4)^(+)-N转化,且不同的外加阳极电势会显著影响BES中NH_(4)^(+)-N的转化速率、氧化产物类型及菌群结构.(图8表1参35)

Microbial electrochemical anodic ammonia oxidation process,a novel nitrogen removal technology,can remedy the defects of a partial nitrification process during urban domestic sewage treatment.Therefore,it is necessary to explore the operating characteristics of this novel technique.Using NH_(4)^(+)-N as the sole substrate,this study was conducted to analyze the transformation rates of NH_(4)^(+)-N,types of oxidation products,and associated microbial community compositions in a two-chambered bioelectrochemical system(BES)with different anode potentials.Furthermore,the effects of the applied anode potential on anode-dependent ammonium oxidation and characteristics of nitrite accumulation in the BES were explored.Based on the results,as the applied anode potential increased from 0.00 to 0.50 V,the initiation of the BES could speed up.Moreover,the anode-dependent ammonium oxidation process was strengthened upon stable BES operation,enhancing the ammonia oxidation efficiency(AOE)and nitrite accumulation efficiency(NiAE)of the system.However,as the applied anode potential was>0.80 V,nitrate was the main nitrogen form in the BES after ammonia oxidation because of oxygen evolution reaction on the working electrode.Notably,the anode-dependent ammonium oxidation was remarkably inhibited in the system once the applied anode potential was increased to 1.00 V,deteriorating the AOE.BES operation with an anode potential of 0.50 V led to Nitrosomonas(relative abundance 40.05%)and Empodebacter(relative abundance 21.92%)as the two dominant bacterial genera in the electroactive ammonia oxidation biofilm,playing key roles in ammonia oxidation.Correspondingly,anode-dependent ammonium oxidation was enhanced most effectively in the system,resulting in an ideal ammonia oxidation[AOE=89.48%(±2.22%)]and high levels of nitrite accumulation[NiAE=88.16%(±2.02%)].An electroactive ammonia oxidation biofilm,which can oxidize ammonia via anode-dependent ammonium oxidation,was cultivated on the surface of the anode in the BES by modulating the electrode potential.Moreover,the transformation rate and oxidation products of ammonium in the BES,as well as the associated microbial community composition,were significantly influenced by the anode potential.