Microprofiles of activated sludge aggregates using microelectrodes in completely autotrophic nitrogen removal over nitrite (CANON) reactor |
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Authors: | Yongtao LV Xuan CHEN Lei WANG Kai JU Xiaoqiang CHEN Rui MIAO Xudong WANG |
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Institution: | 1. School of Environmental and Municipal Engineering, Xi’an University of Architecture and Technology, Xi’an 710055, China2. College of Environment and Resource, Shaanxi University of Science and Technology, Xi’an 710021, China |
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Abstract: | Microsensor measurements and fluorescence in situ hybridization (FISH) analysis were combined to investigate the microbial populations and activities in a laboratory-scale sequencing batch reactor (SBR) for completely autotrophic nitrogen removal over nitrite (CANON). Fed with synthetic wastewater rich in ammonia, the SBR removed 82.5±5.4% of influent nitrogen and a maximum nitrogen-removal rate of 0.52 kgN·m?3·d?1 was achieved. The FISH analysis revealed that aerobic ammonium-oxidizing bacteria (AerAOB) Nitrosomonas and anaerobic ammonium-oxidizing bacteria (AnAOB) dominated the community. To quantify the microbial activities inside the sludge aggregates, microprofiles were measured using pH, dissolved oxygen (DO), NH4+, NO2? and NO3? microelectrodes. In the outer layer of sludge aggregates (0–700 μm), nitrite-oxidizing bacteria (NOB) showed high activity with 4.1 μmol·cm?3·h?1 of maximum nitrate production rate under the condition of DO concentration higher than 3.3 mg·L?1. Maximum AerAOB activity was detected in the middle layer (depths around 1700 μm) where DO concentration was 1.1 mg·L?1. In the inner layer (2200–3500 μm), where DO concentration was below 0.9 mg·L?1, AnAOB activity was detected. We thus showed that information obtained from microscopic views can be helpful in optimizing the SBR performance. |
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Keywords: | microelectrodes CANON aerobic ammonium-oxidizing bacteria anaerobic ammonium-oxidizing bacteria nitrite-oxidizing bacteria |
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