title: Granulation of activated sludge under low hydrodynamic shear and different wastewater characteristics.
abstract: Five reactors were operated with low upflow superficial air velocities (0.41cmmin-1) in order to observe granulation on synthetic wastewaters with different characteristics: 1) 340mg-CODL-1; 2) 630mg-CODL-1; and 3) 1300mg-CODL-1. Stable granulation was only observed under low hydrodynamic shear for low-strength wastewater. 55-70% of soluble chemical oxygen demand (COD) was utilized before aeration and 91% COD, 62% total nitrogen (TN), and 96% total phosphorus (TP) were removed from the low-strength wastewater. Although medium-strength wastewater did generate granules they rapidly acquired a filamentous surface layer that resulted in decreased performance and loss of nitrification. 94% COD, 30% TN, and 85% TP were removed from the medium-strength wastewater. The high-strength wastewater did not develop granules and 85% COD was removed. Results demonstrated that high shear force was not required for granulation. Rather, granulation depended on multiple parameters to out-select rapidly growing aerobic microorganisms.
authors.affiliation: Civil Engineering, University of Manitoba, 15 Gillson St. Room E1-368A, Winnipeg, MB R3T 5V6, Canada. Electronic address: umdevli5@myumanitoba.ca.
authors.forename: T R
authors.initials: TR
authors.lastname: Devlin
authors.affiliation: Civil Engineering, University of Manitoba, 15 Gillson St. Room E1-368A, Winnipeg, MB R3T 5V6, Canada.
authors.forename: A
authors.initials: A
authors.lastname: di Biase
authors.affiliation: Civil Engineering, University of Manitoba, 15 Gillson St. Room E1-368A, Winnipeg, MB R3T 5V6, Canada.
authors.forename: M
authors.initials: M
authors.lastname: Kowalski
authors.affiliation: Civil Engineering, University of Manitoba, 15 Gillson St. Room E1-368A, Winnipeg, MB R3T 5V6, Canada.
authors.forename: J A
authors.initials: JA
authors.lastname: Oleszkiewicz
mesh_terms: D000332:Aerobiosis; D057919:Biological Oxygen Demand Analysis; D019149:Bioreactors; D004867:Equipment Design; D057446:Hydrodynamics; D058465:Nitrification; D009584:Nitrogen / Q000302:isolation & purification / Q000378:metabolism; D010758:Phosphorus / Q000302:isolation & purification / Q000378:metabolism; D012722:Sewage / Q000032:analysis / Q000737:chemistry*; D014865:Waste Disposal, Fluid / Q000295:instrumentation* / Q000379:methods*; D062065:Wastewater / Q000032:analysis / Q000737:chemistry*
chemical_list: D009584:Nitrogen; D010758:Phosphorus; D012722:Sewage; D062065:Wastewater
keywords: Aerobic granular sludge; Biological nutrient removal; Hydrodynamic shear force; Superficial upflow air velocity; Wastewater treatment