title: Specific layers in aerobically grown microbial granules.
abstract: OBJECTIVE
  To determine the optimal size of aerobically grown granules for wastewater treatment by measuring specific layers within the granules.
  
  
  RESULTS
  A variety of biological layers were detected by oligonucleotide probes, specific fluorochromes, and fluorescent microspheres. The channels in the granule matrix penetrated to depths of 900 microm. A layer of obligate anaerobic bacteria was detected at a depth of 800 microm below the granule surface. Dead cells were also observed in the granule interior.
  
  
  CONCLUSIONS
  Aerobically grown granules contained layers of aerobic and anaerobic micro-organisms.
  
  
  CONCLUSIONS
  The optimal diameter of the aerobic granule is less than 1600 microm. This is twice the distance from the granule surface to the anaerobic layer. This approach can be used to optimize the thickness of other microbial aggregates such as flocs, colonies and biofilms.
authors.affiliation: School of Civil and Environmental Engineering, College of Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798.
authors.forename: J-H
authors.initials: JH
authors.lastname: Tay
authors.forename: V
authors.initials: V
authors.lastname: Ivanov
authors.forename: S
authors.initials: S
authors.lastname: Pan
authors.forename: S T-L
authors.initials: ST
authors.lastname: Tay
mesh_terms: D000332:Aerobiosis; D001420:Bacteria, Aerobic / Q000254:growth & development*; D001439:Bacteroides / Q000254:growth & development; D019149:Bioreactors; D002455:Cell Division; D009606:Nitrosomonas / Q000254:growth & development; D010316:Particle Size; D010572:Pest Control, Biological; D011108:Polymers / Q000737:chemistry; D012722:Sewage / Q000382:microbiology; D014871:Water Microbiology
chemical_list: D011108:Polymers; D012722:Sewage