title: Impacts of variable pH on stability and nutrient removal efficiency of aerobic granular sludge.
abstract: The impact of pH variation on aerobic granular sludge stability and performance was investigated. A 9-day alkaline (pH=9) and acidic (pH=6) pH shocks were imposed on mature granules with simultaneous chemical oxygen demand (COD), nitrogen and phosphorus removal. The imposed alkaline pH shock (pH 9) reduced nitrogen and phosphorus removal efficiency from 88% and 98% to 66% and 50%, respectively, with no further recovery. However, acidic pH shock (pH 6) did not have a major impact on nutrient removal and the removal efficiencies recovered to their initial values after 3 days of operation under the new pH condition. Operating the reactors under alkaline pH induced granules breakage and resulted in an increased solids concentration in the effluent and a significant decrease in the size of the bio-particles, while acidic pH did not have significant impacts on granules stability. Changes in chemical structure and composition of extracellular polymeric substances (EPS) matrix were suggested as the main factors inducing granules instability under high pH.
authors.affiliation: Department of Civil Engineering, University of Manitoba, 15 Gillson St., Winnipeg, MB, Canada R3T 5V6 E-mail: lashkarm@myumanitoba.ca.
authors.forename: Monireh
authors.initials: M
authors.lastname: Lashkarizadeh
authors.affiliation: Department of Civil Engineering, University of Manitoba, 15 Gillson St., Winnipeg, MB, Canada R3T 5V6 E-mail: lashkarm@myumanitoba.ca; Department of Civil and Environmental Engineering, University of Florence, Via Santa Marta 3, 50139 Florence, Italy.
authors.forename: Giulio
authors.initials: G
authors.lastname: Munz
authors.affiliation: Department of Civil Engineering, University of Manitoba, 15 Gillson St., Winnipeg, MB, Canada R3T 5V6 E-mail: lashkarm@myumanitoba.ca.
authors.forename: Jan A
authors.initials: JA
authors.lastname: Oleszkiewicz
mesh_terms: D057919:Biological Oxygen Demand Analysis; D019149:Bioreactors; D006863:Hydrogen-Ion Concentration; D009584:Nitrogen / Q000302:isolation & purification; D010758:Phosphorus / Q000302:isolation & purification; D012722:Sewage / Q000737:chemistry*; D018508:Water Purification
chemical_list: D012722:Sewage; D010758:Phosphorus; D009584:Nitrogen