title: Structure analysis of aerobic granule from a sequencing batch reactor for organic matter and ammonia nitrogen removal.
abstract: Aerobic granules were cultivated in a sequencing batch reactor (SBR). COD and ammonia nitrogen removal rate were 94% and 99%, respectively. The diameter, settling velocity and SVI10 of granules ranged from 2 to 5 mm, 80 to 110 m/h and about 40 mL/g, respectively. Freezing microtome images, DO concentration profiles by microelectrode, distribution of bacteria and EPS by confocal laser scanning microscopy (CLSM) show that the aerobic granules have a three-layer structure. Each layer has different thickness, character, bacteria, and DO transfer rate. A hypothesis for granule structure is proposed: the first layer, the surface of the granule, is composed mostly of heterotrophic organisms for organic matter removal, with a thickness range from 150 to 350 μm; the second layer, mostly composed of autotrophic organisms for ammonia nitrogen removal, with a thickness range from 250 to 450 μm; the third layer, located in the core of the granule, has mostly an inorganic composition and contains pores and channels.
authors.affiliation: College of Civil Engineering and Architecture, Zhejiang University of Technology, Hangzhou 310014, China. tanweilijun@zjut.edu.cn.
authors.forename: Jun
authors.initials: J
authors.lastname: Li
authors.affiliation: College of Civil Engineering and Architecture, Zhejiang University of Technology, Hangzhou 310014, China. caiang123@163.com.
authors.forename: Ang
authors.initials: A
authors.lastname: Cai
authors.affiliation: College of Civil Engineering and Architecture, Zhejiang University of Technology, Hangzhou 310014, China. wangdanjun0509@163.com.
authors.forename: Danjun
authors.initials: D
authors.lastname: Wang
authors.affiliation: College of Civil Engineering and Architecture, Zhejiang University of Technology, Hangzhou 310014, China. cc622368@126.com.
authors.forename: Chao
authors.initials: C
authors.lastname: Chen
authors.affiliation: College of Civil Engineering and Architecture, Zhejiang University of Technology, Hangzhou 310014, China. niyongjiong1984@163.com.
authors.forename: Yongjiong
authors.initials: Y
authors.lastname: Ni
mesh_terms: D000332:Aerobiosis; D064751:Ammonium Compounds / Q000302:isolation & purification; D057919:Biological Oxygen Demand Analysis; D019149:Bioreactors; D008839:Microelectrodes; D018613:Microscopy, Confocal; D009930:Organic Chemicals / Q000302:isolation & purification; D014866:Waste Products / Q000032:analysis*
chemical_list: D064751:Ammonium Compounds; D009930:Organic Chemicals; D014866:Waste Products