以不锈钢筒作为阴极、碳毡作为阳极,阴阳极间利用无纺布作为隔膜构建单室生物电解池,以氨作为唯一电子供体,接入混合菌群,通过恒定不同的阳极电势,考察不同初始浓度氨氮在生物电解池内的氧化与产物的生成情况.结果表明,恒定阳极电势0.2 V(vs Ag/Ag Cl)时,经过5 d的运行,初始氨氮浓度200 mg/L、400 mg/L的氨氮去除率分别为30%、35%,氮气分别积累16.1 m L、17.18 m L,甲烷分别积累1.18 m L、1.46 m L;恒定阳极电势0.6 V(vs Ag/Ag Cl)时,初始氨氮浓度200 mg/L、400 mg/L,氨氮去除率分别为32.4%、36.6%,分别积累氮气16.48 m L、17.42 m L,积累甲烷1.3m L、1.52 m L,未检测到硝态氮和亚硝态氮.循环伏安扫描分析发现,阳极具有明显的氧化还原峰,且不同的阳极恒定电势,导致其氧化还原峰出现偏移.通过电镜扫描,发现阳极微生物细胞表面具有明显的褶皱形状,高通量分析显示阳极微生物中Geobacter占24.11%,是优势菌群,在阳极氨氧化过程中起到关键作用.同时发现系统中还存在氢营养型产甲烷菌Synergistes(3.8%)以及梭菌Clo stridium(3.8%)和Gordonia(1.85%)等功能微生物.本文研究表明,在生物电解池内,微生物能够以氨氮作为电子供体,通过氨氧化脱氮,并产生氢气和甲烷.
In this study, a microbial electrolysis cell (MEC) was constructed with stainless steel tube as the cathode, carbon felt as the anode, nonwoven fabric as the separator between the two electrodes. Ammonia was the only electron donor, and mixed microbes inoculated in the cell. Through setting the different anode potentials, the products of ammonia oxidation under different ammonia concentrations were studied. The results showed that when the ammonium concentration was 200 mg/L and 400 mg/L, after 5 days' operation under 0.2 V (vs Ag/AgC1) anode potential, the ammonia nitrogen removal rate reached 30% and 35% respectively. Additionally, 16.1 mL nitrogen and 1.18 mL methane were generated in the 200 mg/L system, while 17.18 mL and 1.46 mL for the 400 mg/L system. When the anode potential was adjusted to 0.6 V (vs Ag/AgC1), the ammonia nitrogen removal rate raised to 32.4% and 36.6% for the 200 mg/L and 400 mg/L system respectively. The production of nitrogen and methane were 16.48 mL and 1.3 mL for 200 mg/L system, while 17.42 mL and 1.52 mL for 400 mg/L system. During the operation period, no nitrate or nitrite nitrogen was detected. Cyclic voltammetry tests suggested that the anode had obvious redox peaks, and the location of the redox peaks would change by different anode potential. SEM indicated that the surface of the anode microorganisms had obvious fold shape. The high-throughput sequencing showed that Geobacter (24.11%) was the dominant population on the anode playing an important role in the ammonium oxidation process. The other functional microbes Synergistes (3.8%), Clostridium (3.8%) and Gordonia (1.85%) were also observed. The results of the experiment suggested that microorganisms are able to use ammonium as electron donor and produce hydrogen and methane in this MEC.