title: Biosolids reduction by the oxic-settling-anoxic process: Impact of sludge interchange rate.
abstract: The impact of sludge interchange rate (SIR) on sludge reduction by oxic-settling-anoxic (OSA) process was investigated. The sludge yield of an OSA system (a sequencing batch reactor, SBR, integrated with external anoxic reactors) was compared to that of a control (an SBR attached to a single-pass aerobic digester). SIR (%) is the percentage by volume of sludge returned from the external reactor into the main bioreactor of the OSA, and was varied from 0% to 22%. OSA achieved greater sludge reduction when fed with unsettled sewage (sCOD=113mg/L) rather than settled sewage (sCOD=60mg/L). The SIR of 11% resulted in the highest OSA performance. At the optimum SIR, higher volatile solids destruction and nitrification/denitrification (i.e., conversion of destroyed volatile solids into inert forms) were observed in the external anoxic and intermittently aerated (i.e., aerobic/anoxic) reactors, respectively. Denitrification in the aerobic/anoxic reactor was inefficient without SIR. Effluent quality and sludge settleability of the main SBR were unaffected by SIR.
authors.affiliation: Strategic Water Infrastructure Laboratory, School of Civil, Mining and Environmental Engineering, University of Wollongong, Wollongong, NSW 2522, Australia.
authors.forename: Galilee U
authors.initials: GU
authors.lastname: Semblante
authors.affiliation: Strategic Water Infrastructure Laboratory, School of Civil, Mining and Environmental Engineering, University of Wollongong, Wollongong, NSW 2522, Australia. Electronic address: faisal@uow.edu.au.
authors.forename: Faisal I
authors.initials: FI
authors.lastname: Hai
authors.affiliation: Sydney Water, Parramatta, NSW 2124, Australia.
authors.forename: Heriberto
authors.initials: H
authors.lastname: Bustamante
authors.affiliation: Sydney Water, Parramatta, NSW 2124, Australia.
authors.forename: Nelly
authors.initials: N
authors.lastname: Guevara
authors.affiliation: Strategic Water Infrastructure Laboratory, School of Chemistry, University of Wollongong, Wollongong, NSW 2522, Australia.
authors.forename: William E
authors.initials: WE
authors.lastname: Price
authors.affiliation: Strategic Water Infrastructure Laboratory, School of Civil, Mining and Environmental Engineering, University of Wollongong, Wollongong, NSW 2522, Australia.
authors.forename: Long D
authors.initials: LD
authors.lastname: Nghiem
mesh_terms: D000332:Aerobiosis; D000641:Ammonia / Q000302:isolation & purification; D000693:Anaerobiosis; D001673:Biodegradation, Environmental; D057919:Biological Oxygen Demand Analysis; D019149:Bioreactors / Q000382:microbiology; D009566:Nitrates / Q000302:isolation & purification; D009573:Nitrites / Q000302:isolation & purification; D010084:Oxidation-Reduction; D010710:Phosphates / Q000302:isolation & purification; D012722:Sewage / Q000737:chemistry*; D014865:Waste Disposal, Fluid / Q000379:methods*; D062065:Wastewater / Q000737:chemistry
chemical_list: D000641:Ammonia; D009566:Nitrates; D009573:Nitrites; D010710:Phosphates; D012722:Sewage; D062065:Wastewater
keywords: Denitrification; Oxic-settling-anoxic; Sludge interchange rate; Sludge/biosolids reduction