title: Microstructural strength deterioration of aerobic granule sludge under organic loading swap.
abstract: This study revealed that the gross indicators commonly adopted for monitoring the performance of aerobic granular sludge processes are not capable of probing the microstructural deterioration of granule interior upon organic loading swaps. These granules subjected to loading swaps retained their global characteristics: appearances, sizes and settling velocities, chemical oxygen demand (COD) and ammonia-nitrogen removal capacities. However, the granule interior strength, as determined by ultrasound method, was largely weakened upon COD switch-off and was not recovered in the subsequent COD re-supply stage. In response to COD switch-off, the 5.6kDa polysaccharides component of granule extracellular polymeric substances (EPS) was diminished. Correspondingly, two bacterial species, Thauera and Sphingomonas sp., were faded away together with the significant decline in contents of intracellular cyclic dimeric GMP (c-di-GMP). The microstructural integrity of granules was seriously deteriorated upon COD switch-off, which was not detectable by the commonly adopted gross indicators.
authors.affiliation: Department of Environmental Science and Engineering, Fudan University, Shanghai 200433, China.
authors.forename: Chunli
authors.initials: C
authors.lastname: Wan
authors.affiliation: College of Materials Science and Chemical Engineering, Harbin Engineering University, Harbin 150001, China.
authors.forename: Yanggui
authors.initials: Y
authors.lastname: Shen
authors.affiliation: Department of Environmental Science and Engineering, Fudan University, Shanghai 200433, China.
authors.forename: Si
authors.initials: S
authors.lastname: Chen
authors.affiliation: Department of Environmental Science and Engineering, Fudan University, Shanghai 200433, China.
authors.forename: Xiang
authors.initials: X
authors.lastname: Liu
authors.affiliation: College of Materials Science and Chemical Engineering, Harbin Engineering University, Harbin 150001, China.
authors.forename: Guangmin
authors.initials: G
authors.lastname: Liu
authors.affiliation: R&D Center for Membrane Technology, Department of Chemical Engineering, Chung Yuan Christian University, Chungli, Taiwan.
authors.forename: Juin-Yih
authors.initials: JY
authors.lastname: Lai
authors.affiliation: R&D Center for Membrane Technology, Department of Chemical Engineering, Chung Yuan Christian University, Chungli, Taiwan; Department of Chemical Engineering, National Taiwan University of Science and Technology, Taipei 10607, Taiwan; Department of Chemical Engineering, National Taiwan University, Taipei 10617, Taiwan. Electronic address: djleetw@yahoo.com.tw.
authors.forename: Duu-Jong
authors.initials: DJ
authors.lastname: Lee
mesh_terms: D000332:Aerobiosis; D057919:Biological Oxygen Demand Analysis; D019149:Bioreactors / Q000382:microbiology*; D006152:Cyclic GMP / Q000031:analogs & derivatives / Q000378:metabolism; D006714:Homoserine / Q000031:analogs & derivatives / Q000378:metabolism; D007783:Lactones / Q000378:metabolism; D059013:Microbial Consortia / Q000502:physiology*; D011134:Polysaccharides / Q000378:metabolism; D012722:Sewage / Q000737:chemistry* / Q000382:microbiology; D014865:Waste Disposal, Fluid / Q000295:instrumentation / Q000379:methods*
chemical_list: D007783:Lactones; C091088:N-octanoylhomoserine lactone; D011134:Polysaccharides; D012722:Sewage; C062025:bis(3',5')-cyclic diguanylic acid; D006714:Homoserine; D006152:Cyclic GMP
keywords: Bacterial community; Extracellular polymeric substances; Signal molecules; Strength