title: Mechanisms and models for anaerobic granulation in upflow anaerobic sludge blanket reactor.
abstract: Upflow anaerobic sludge blanket (UASB) reactor has been employed in industrial and municipal wastewater treatment for decades. However, the long start-up period required for the development of anaerobic granules seriously limits the application of this technology. In order to develop the strategy for rapid UASB start-up, the mechanisms for anaerobic granulation should be understood. This paper attempts to provide a up-to-date review on the existing mechanisms and models for anaerobic granulation in the UASB reactor, which include inert nuclei model, selection pressure model, multi-valence positive ion-bonding model, synthetic and natural polymer-bonding model, Capetown's model, spaghetti theory, syntrophic microcolony model, multi-layer model, secondary minimum adhesion model, local dehydration and hydrophobic interaction model, surface tension model, proton translocation-dehydration theory, cellular automaton model and cell-to-cell communication model. Based on those previous works, a general model for anaerobic granulation is also proposed. It is expected that this paper would be helpful for researchers to further develop a unified theory for anaerobic granulation and technology for expediting the formation of the UASB granules.
authors.affiliation: Environmental Engineering Research Centre, School of Civil and Environmental Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798, Singapore. cyliu@ntu.edu.sg
authors.forename: Yu
authors.initials: Y
authors.lastname: Liu
authors.forename: Hai-Lou
authors.initials: HL
authors.lastname: Xu
authors.forename: Shu-Fang
authors.initials: SF
authors.lastname: Yang
authors.forename: Joo-Hwa
authors.initials: JH
authors.lastname: Tay
mesh_terms: D001421:Bacteria, Anaerobic / Q000502:physiology; D001422:Bacterial Adhesion; D019149:Bioreactors; D002450:Cell Communication; D008962:Models, Theoretical; D010316:Particle Size; D014865:Waste Disposal, Fluid / Q000379:methods*; D014872:Water Movements