生物电化学措施下SBBR中的亚硝酸盐累积性能及微生物学特征

Accumulation performances of nitrite and associated microbiological characteristics in a sequencing batch biofilm reactor assisted by bioelectrochemical technology

针对常温下生活污水短程硝化难以实现且稳定性差的难题,探究了生物电化学措施对序批式生物膜反应器(SBBR)中NO_(2)^(−)-N的累积性能及微生物学特征的影响。对SBBR施加生物电化学措施后,通过调控外加电极电势可实现其中电极氨氧化作用的发生及强化,且不同的外加阳极电势会显著影响系统中NH_(4)^(+)-N的转化效果、氧化产物类型及菌群结构。随着外加阳极电势由0.00增至0.50 V,SBBR中电极氨氧化作用的强度逐步提高,系统的NH_(4)^(+)-N氧化效率(AOE)与NO_(2)^(−)-N累积效率(NiAE)分别增至(97.07±1.20)%和(92.79±2.12)%;当外加阳极电势≥0.80 V后,SBBR中NH_(4)^(+)-N的氧化产物因工作电极上的析氧反应转而以NO_(3)^(−)-N为主,电极氨氧化作用的强度因电势不断升高而受到抑制,系统的AOE随之恶化。将外加阳极电势恒定为0.50 V,生物电化学强化型SBBR在常温下处理生活污水时可取得理想的NH_(4)^(+)-N转化效率(AOE=(99.33±0.11)%)与较高水平的亚硝酸盐累积量(NiAE=(88.08±2.07)%),此时系统中的电极氨氧化作用可得到较大程度的强化,其电活性生物膜中的优势菌属包括Nitrosomonas(33.54%)、Geobacter(15.24%)和Empodebacter(16.88%),三者在NH_(4)^(+)-N厌氧氧化过程中起关键作用。

Considering the difficulties of achievement and stability of partial nitrification when treating domestic sewage at ambient temperature,the experiments were conducted to explore the effects of bioelectrochemical assisted approach on nitrite accumulation performances and associated microbiological characteristics in a sequencing batch biofilm reactor(SBBR).When SBBR was assisted by bioelectrochemical technology,the regulation of the electrode potential could realize the cccurrence and enhancement of the electrode dependent ammonium oxidation process.Further,the different anode potential levels could significantly affect the transformation performances and oxidation product types of ammonium in the system,as well as the associated microbial community structures.As the applied anode potential increased from 0.00 to 0.50 V,the strength of the electrode dependent ammonium oxidation process increased gradually in the SBBR,and the ammonia oxidation efficiency(AOE)and nitrite accumulation efficiency(NiAE)of the system increased to(97.07±1.20)%and(92.79±2.12)%,respectively.As the applied anode potential was higher than 0.80 V,the products of ammonium oxidation in SBBR mainly changed into nitrate owing to occurrence of oxygen evolution reaction on the working electrode.Moreover,the electrode dependent ammonium oxidation process began to be inhibited in the system due to the increased anode potential levels,deteriorating the AOE.Regarding to the bioelectrochemical assisted SBBR operating with the applied anode potential of 0.50 V,ideal ammonia oxidation effect[AOE=(99.33±0.11)%]and high level of nitrite accumulation amount[NiAE=(88.08±2.07)%]could be achieved when the system was used to treat domestic sewage at ambient temperature.Correspondingly,the electrode dependent ammonium oxidation process could be highly strengthened in the reactor,Nitrosomonas(the relative abundance of 33.54%),Geobacter(the relative abundance of 15.24%)and Empodebacter(the relative abundance of 16.88%)were the three dominant bacterial genera in the electroactive biofilm,which played key roles in the process of anaerobic ammonia oxidation.