title: The structure, density and settlability of anammox granular sludge in high-rate reactors.
abstract: Microscopic observation and settling test were carried out to investigate the structure, density and settlability of anammox granules taken from a high-rate upflow anaerobic sludge blanket (UASB) reactor. The results showed that the anammox granules were irregular in shape and uneven on surface, and their structure included granule, subunit, microbial cell cluster and single cell. The gas pockets were often observed in the anammox granules, and they originated from the obstruction of gas tunnel by extracellular polymer substances (EPSs) and the inflation of produced dinitrogen gas. The volume of gas pockets became larger with the increasing diameter of anammox granules, which led to the decreasing density and the floatation of anammox granules. The diameter of anammox granules should be controlled at less than 2.20mm to avoid the granule floatation. A hypothesized mechanism for the granulation and floatation of anammox biomass was proposed.
authors.affiliation: Department of Environmental Engineering, Zhejiang University, Hangzhou 310058, China.
authors.forename: Hui-Feng
authors.initials: HF
authors.lastname: Lu
authors.forename: Ping
authors.initials: P
authors.lastname: Zheng
authors.forename: Qi-Xing
authors.initials: QX
authors.lastname: Ji
authors.forename: Hong-Tao
authors.initials: HT
authors.lastname: Zhang
authors.forename: Jun-Yuan
authors.initials: JY
authors.lastname: Ji
authors.forename: Lan
authors.initials: L
authors.lastname: Wang
authors.forename: Shuang
authors.initials: S
authors.lastname: Ding
authors.forename: Ting-Ting
authors.initials: TT
authors.lastname: Chen
authors.forename: Ji-Qiang
authors.initials: JQ
authors.lastname: Zhang
authors.forename: Chong-Jian
authors.initials: CJ
authors.lastname: Tang
authors.forename: Jian-Wei
authors.initials: JW
authors.lastname: Chen
mesh_terms: D000693:Anaerobiosis; D001419:Bacteria / Q000166:cytology / Q000378:metabolism / Q000648:ultrastructure; D018533:Biomass; D019149:Bioreactors / Q000382:microbiology*; D005740:Gases / Q000032:analysis; D010084:Oxidation-Reduction; D000644:Quaternary Ammonium Compounds / Q000378:metabolism*; D012722:Sewage / Q000737:chemistry* / Q000382:microbiology*
chemical_list: D005740:Gases; D000644:Quaternary Ammonium Compounds; D012722:Sewage