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Microprofiles of activated sludge aggregates using microelectrodes in completely autotrophic nitrogen

Yongtao LV,Xuan CHEN,Lei WANG,Kai JU,Xiaoqiang CHEN,Rui MIAO,Xudong WANG

《环境科学与工程前沿（英文）》 2016年第10卷第2期页码 390-398 doi: 10.1007/s11783-015-0818-6

摘要： 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 ·d was achieved. The FISH analysis revealed that aerobic ammonium-oxidizing bacteria (AerAOB) 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), , and microelectrodes. In the outer layer of sludge aggregates (0–700 μm), nitrite-oxidizing bacteria (NOB) showed high activity with 4.1 μmol·cm ·h of maximum nitrate production rate under the condition of DO concentration higher than 3.3 mg·L . Maximum AerAOB activity was detected in the middle layer (depths around 1700 μm) where DO concentration was 1.1 mg·L . In the inner layer (2200–3500 μm), where DO concentration was below 0.9 mg·L , AnAOB activity was detected. We thus showed that information obtained from microscopic views can be helpful in optimizing the SBR performance.

关键词： microelectrodes CANON aerobic ammonium-oxidizing bacteria anaerobic ammonium-oxidizing bacteria nitrite-oxidizing bacteria

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Micro-analysis of nitrogen transport and conversion inside activated sludge flocs using microelectrodes

Lei WANG, Yongtao LV, Xudong WANG, Yongzhe YANG, Xiaorong BAI

《环境科学与工程前沿（英文）》 2011年第5卷第4期页码 633-638 doi: 10.1007/s11783-011-0329-z

摘要： To investigate the nitrogen transport and conversion inside activated sludge flocs, micro-profiles of O , NH , NO , NO , and pH were measured under different operating conditions. The flocs were obtained from a laboratory-scale sequencing batch reactor. Nitrification, as observed from interfacial ammonium and nitrate fluxes, was higher at pH 8.5, than at pH 6.5 and 7.5. At pH 8.5, heterotrophic bacteria used less oxygen than nitrifying bacteria, whereas at lower pH heterotrophic activity dominated. When the ratio of C to N was decreased from 20 to 10, the ammonium uptake increased. When dissolved oxygen (DO) concentration in the bulk liquid was decreased from 4 to 2 mg·L , nitrification decreased, and only 25% of the DO influx into the flocs was used for nitrification. This study indicated that nitrifying bacteria became more competitive at a higher DO concentration, a higher pH value (approximately 8.5) and a lower C/N.

关键词： nitrogen transport activated sludge flocs heterotrophic bacteria nitrifying bacteria microelectrodes