Aerobic granules seeded with activated sludge flocs and pellets （obtained from activated sludge flocs） were cultivated in two sequencing batch reactors and their characteristics were compared. Compared with granules...Aerobic granules seeded with activated sludge flocs and pellets （obtained from activated sludge flocs） were cultivated in two sequencing batch reactors and their characteristics were compared. Compared with granules seeded with activated sludge flocs, those seeded with pellets had shorter start-up time, larger diameter, better chemical oxygen demand removal efficiency, and higher hydrophobicity, suspended solid concentration, and Mg 2＋ content. The different inocula led the granule surface with different microbial morphologies, but did not result in different distribution patterns of extracellular polymeric substances and cells. The anaerobic bacterium Anoxybacillus sp. was detected in the granules seeded with pellets. These results highlighted the advantage of pellet over activated sludge floc as the seed for aerobic granulation and wastewater treatment.展开更多
To investigate the nitrogen transport and conversion inside activated sludge flocs,micro-profiles of O2,NHt 4,NO-2,NO-3,and pH were measured under different operating conditions.The flocs were obtained from a laborato...To investigate the nitrogen transport and conversion inside activated sludge flocs,micro-profiles of O2,NHt 4,NO-2,NO-3,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^(-1),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.展开更多
基金supported by the National Natural Science Foundation of China(No.20977066)the National Key Project for Water Pollution Control(No.2008ZX07316-002,2008ZX07317-003)the Specialized Research Fund for Doctoral Program of Higher Education of China(No.200802470029)
文摘Aerobic granules seeded with activated sludge flocs and pellets （obtained from activated sludge flocs） were cultivated in two sequencing batch reactors and their characteristics were compared. Compared with granules seeded with activated sludge flocs, those seeded with pellets had shorter start-up time, larger diameter, better chemical oxygen demand removal efficiency, and higher hydrophobicity, suspended solid concentration, and Mg 2＋ content. The different inocula led the granule surface with different microbial morphologies, but did not result in different distribution patterns of extracellular polymeric substances and cells. The anaerobic bacterium Anoxybacillus sp. was detected in the granules seeded with pellets. These results highlighted the advantage of pellet over activated sludge floc as the seed for aerobic granulation and wastewater treatment.
基金This work was supported by Program for Changjiang Scholars and Innovative Research Team in University(No.IRT0853)State Commission of Science Technology of China(No.2009ZX07212-002)+1 种基金State Key Laboratory of Western Architecture and Technology(No.10KF08)Foundation of Shaanxi Educational Committee(No.11JK0759).
文摘To investigate the nitrogen transport and conversion inside activated sludge flocs,micro-profiles of O2,NHt 4,NO-2,NO-3,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^(-1),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.
