Li Tinggang, Liu Junxin
Institute of Process Engineering, Chinese Academy of Sciences Beijing 100190 People's Republic of China
Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences Beijing 100085 People's Republic of China
RSC Adv. 2019 Sep 17;9(50):29337-29346. doi: 10.1039/c9ra03128f. eCollection 2019 Sep 13.
Membrane-aerated biofilms (MABs) developed with a novel counter-diffusion configuration in oxygen and substrate supply were examined for the effect of biofilm thickness on the functional activity and microbial community structure of the biofilm with the simultaneous degradation of acetonitrile, and nitrification and denitrification. Results demonstrated that different biofilm thicknesses under different surface loading rates (SLRs) caused substantially varied profiles of the microbial activities with distinct functions in the biofilm. Both thick and thin MABs achieved high-rate performance in terms of acetonitrile removal (>99%), but the performance differed in the removal efficiencies of total nitrogen (TN), which was 1.3 times higher in the thick MAB (85%) than in the thin MAB (36.3%). The specific ammonia-oxidizing rate (SAOR) and the specific acetonitrile-degrading rate (SADR) exhibited similar declining and ascending trends in both the thin and thick MABs, respectively. In contrast, the specific denitrifying rate (SDNR) was relatively uniform at a concentration near the detection limit in the thin MAB but exhibited a hump-shaped variation with the highest rate occurring in an intermediate region in the thick MAB. Microbial community analysis revealed a dramatic shift in the dominant bacteria of the community composition with low diversity across the biofilm. This study suggests that the biofilm thickness developed under SLRs, which controls the mass transfer of oxygen and substrates into biofilms, is an important factor affecting the structural and functional stratification of bacterial populations in a single MAB treating organonitrile wastewater.
研究了采用新型氧气和底物供应反向扩散配置培养的膜曝气生物膜（MABs），考察生物膜厚度对生物膜功能活性和微生物群落结构的影响，同时进行乙腈降解、硝化和反硝化。结果表明，在不同表面负荷率（SLRs）下，不同的生物膜厚度导致生物膜中具有不同功能的微生物活性分布有很大差异。厚生物膜和薄生物膜在乙腈去除率方面均达到了高速率性能（>99%），但总氮（TN）去除效率不同，厚生物膜（85%）的总氮去除效率比薄生物膜（36.3%）高倍。薄生物膜和厚生物膜中的比氨氧化速率（SAOR）和比乙腈降解速率（SADR）分别呈现出相似的下降和上升趋势。相比之下，薄生物膜中比反硝化速率（SDNR）在接近检测限的浓度下相对均匀，而厚生物膜中比反硝化速率呈现驼峰状变化，最高速率出现在中间区域。微生物群落分析表明，整个生物膜中优势细菌在群落组成上发生了显著变化，多样性较低。本研究表明，在表面负荷率下形成的生物膜厚度控制着氧气和底物向生物膜中的传质，是影响单一MAB处理有机腈废水时细菌种群结构和功能分层的重要因素。
