title: Comparison of an anaerobic feed and split anaerobic-aerobic feed on granular sludge development, performance and ecology.
abstract: The retrofitting of existing wastewater sequencing batch reactors (SBRs) to select for rapid-settling aerobic granular sludge (AGS) over floc-based conventional activated sludge (CAS), could be a viable option to decrease reactor cycle time and increase hydraulic capacity. Successful CAS-to-AGS conversion has previously been shown to be highly dependent on having a dedicated anaerobic feed, which presents additional engineering challenges when retrofitting SBRs. In this study we compared the performance of a split anaerobic-aerobic (An-Aer) feed with that of a traditional dedicated anaerobic feed regarding AGS formation and stability, nitrogen removal performance and microbial ecology. Using pilot trials, we showed that AGS could be established and maintained when using a split An-Aer feed at low organic loading rates analogous to that of a parallel full-scale conventional SBR. Additionally, we showed that AGS start-up time and nitrogen removal performance were comparable under a split An-Aer feed and dedicated anaerobic feed. Microbial ecology characterisations based on whole-of-community 16S rRNA profiles and targeted analysis of functional genes specific for nitrifying and denitrifying microorganisms, showed that the two different feed strategies had only subtle impacts on both the overall community composition and functional ecology. A much greater divergence in microbial ecology was seen when comparing AGS with CAS. Data presented here will be of value to those planning to retrofit existing CAS-based SBRs to operate with AGS and demonstrates the viability of using a more cost-effective split An-Aer feed configuration over a dedicated anaerobic feed.
authors.affiliation: School of Civil and Environmental Engineering, University of New South Wales, Kensington, 2052, New South Wales, Australia; South Australian Water Corporation, Adelaide, 5000, South Australia, Australia. Electronic address: b.thwaites@student.unsw.edu.au.
authors.forename: Benjamin J
authors.initials: BJ
authors.lastname: Thwaites
authors.affiliation: South Australian Water Corporation, Adelaide, 5000, South Australia, Australia.
authors.forename: Petra
authors.initials: P
authors.lastname: Reeve
authors.affiliation: South Australian Water Corporation, Adelaide, 5000, South Australia, Australia.
authors.forename: Nirmala
authors.initials: N
authors.lastname: Dinesh
authors.affiliation: School of Natural and Built Environments, University of South Australia, Mawson Lakes, 5095, South Australia, Australia; UNSW Water Research Centre, School of Civil and Environmental Engineering, University of New South Wales, Sydney, New South Wales, 2052, Australia; Future Industries Institute, University of South Australia, Mawson Lakes, 5095, South Australia, Australia.
authors.forename: Michael D
authors.initials: MD
authors.lastname: Short
authors.affiliation: South Australian Water Corporation, Adelaide, 5000, South Australia, Australia; School of Natural and Built Environments, University of South Australia, Mawson Lakes, 5095, South Australia, Australia; Health and Environment Group, School of the Environment, Flinders University, Bedford Park, 5042, South Australia, Australia.
authors.forename: Ben
authors.initials: B
authors.lastname: van den Akker
mesh_terms: D000332:Aerobiosis; D000383:Agriculture; D000693:Anaerobiosis; D018533:Biomass; D019149:Bioreactors; D004867:Equipment Design; D009584:Nitrogen / Q000737:chemistry*; D012336:RNA, Ribosomal, 16S / Q000737:chemistry / Q000235:genetics; D012722:Sewage / Q000737:chemistry*; D014865:Waste Disposal, Fluid / Q000379:methods*; D062065:Wastewater; D014871:Water Microbiology
chemical_list: D009584:Nitrogen; D012336:RNA, Ribosomal, 16S; D012722:Sewage; D062065:Wastewater
keywords: Aerobic feed; Aerobic granular sludge; Anaerobic feed; Microbial community ecology; Nutrient removal; SBR; qPCR