title: Anaerobic sludge granulation.
abstract: This paper reviews different theories on anaerobic sludge granulation in UASB-reactors that have been proposed during the past two decades. The initial stages of the formation of anaerobic granules follow the same principles as biofilm formation of bacteria on solid surfaces. There exist strong evidence that inert carriers play an important positive role in granulation. Most researchers conclude that Methanosaeta concilii is a key organism in granulation. Only the Cape Town Hypothesis presumes that an autotrophic hydrogenotrophic organism, i.e., Methanobacterium strain AZ, growing under conditions of high H(2)-pressures, is the key organism in granulation. Many authors focus on the initial stage of granulation, and only a few contributions discuss the latter stages in granulation: granule maturation and multiplication. Granule enhancing factors in the latter stages predominantly rely on manipulation of the selection pressure, through which selectively heavier sludge particles are retained in the UASB reactor.
authors.affiliation: Sub-Department of Environmental Technology, Agricultural University of Wageningen, "Biotechnion" Bomenweg 2, PO Box 8129, 6700 EV Wageningen, The Netherlands.
authors.forename: L W
authors.initials: LW
authors.lastname: Hulshoff Pol
authors.forename: S I
authors.initials: SI
authors.lastname: de Castro Lopes
authors.forename: G
authors.initials: G
authors.lastname: Lettinga
authors.forename: P N L
authors.initials: PN
authors.lastname: Lens
mesh_terms: D001421:Bacteria, Anaerobic / Q000502:physiology*; D019149:Bioreactors; D019640:Methanosarcinales / Q000502:physiology*; D010316:Particle Size; D012722:Sewage / Q000737:chemistry / Q000382:microbiology*; D014865:Waste Disposal, Fluid / Q000379:methods
chemical_list: D012722:Sewage