title: An 'omics' approach towards the characterisation of laboratory scale anaerobic digesters treating municipal sewage sludge.
abstract: In this study, laboratory scale digesters were operated to simulate potential shocks to the Anaerobic Digestion (AD) process at a 350 ML/day wastewater treatment plant. The shocks included high (42 °C) and low (32 °C) temperature (either side of mesophilic 37 °C) and a 20% loading of fats, oil and grease (FOG; 20% w:v). These variables were explored at two sludge retention times (12 and 20 days) and two organic loading rates (2.0 and 2.5 kgTS/m(3)day OLR). Metagenomic and metabolomic approaches were then used to characterise the impact of operational shocks in regard to temperature and FOG addition, as determined through monitoring of biogas production, the microbial profile and their metabolism. Results showed that AD performance was not greatly affected by temperature shocks, with the biggest impact being a reduction in biogas production at 42 °C that persisted for 32 ± 1 days. The average biogas production across all digesters at the completion of the experiment was 264.1 ± 76.5 mL/day, with FOG addition observed to significantly promote biogas production (+87.8 mL/day). Metagenomic and metabolomic analyses of the digesters indicated that methanogens and methane oxidising bacteria (MOB) were low in relative abundance, and that the ratio of oxidising bacteria (methane, sulphide and sulphate) with respect to sulphate reducing bacteria (SRB) had a noticeable influence on biogas production. Furthermore, increased biogas production correlated with an increase in short chain fatty acids, a product of the addition of 20% FOG. This work demonstrates the application of metagenomics and metabolomics to characterise the microbiota and their metabolism in AD digesters, providing insight to the resilience of crucial microbial populations when exposed to operational shocks.
authors.affiliation: Land and Water, Commonwealth Scientific and Industrial Research Organisation, PO Box 2583, Brisbane, Queensland 4001, Australia. Electronic address: david.beale@csiro.au.
authors.forename: D J
authors.initials: DJ
authors.lastname: Beale
authors.affiliation: Land and Water, Commonwealth Scientific and Industrial Research Organisation, PO Box 2583, Brisbane, Queensland 4001, Australia; Faculty of Science, Engineering and Technology, Swinburne University of Technology, PO Box 218, Hawthorn, Victoria 3122, Australia.
authors.forename: A V
authors.initials: AV
authors.lastname: Karpe
authors.affiliation: School of Civil, Environmental and Chemical Engineering, RMIT University, GPO Box 2476, Melbourne, Victoria 3001, Australia.
authors.forename: J D
authors.initials: JD
authors.lastname: McLeod
authors.affiliation: Centre for Human Psychopharmacology, Faculty of Health, Arts and Design, Swinburne University of Technology, PO Box 218, Hawthorn, Victoria 3122, Australia.
authors.forename: S V
authors.initials: SV
authors.lastname: Gondalia
authors.affiliation: Land and Water, Commonwealth Scientific and Industrial Research Organisation, PO Box 2583, Brisbane, Queensland 4001, Australia.
authors.forename: T H
authors.initials: TH
authors.lastname: Muster
authors.affiliation: School of Civil, Environmental and Chemical Engineering, RMIT University, GPO Box 2476, Melbourne, Victoria 3001, Australia.
authors.forename: M Z
authors.initials: MZ
authors.lastname: Othman
authors.affiliation: Faculty of Science, Engineering and Technology, Swinburne University of Technology, PO Box 218, Hawthorn, Victoria 3122, Australia.
authors.forename: E A
authors.initials: EA
authors.lastname: Palombo
authors.affiliation: Melbourne Water, PO Box 4342, Melbourne, Victoria 3001, Australia.
authors.forename: D
authors.initials: D
authors.lastname: Joshi
mesh_terms: D000693:Anaerobiosis; D001105:Archaea / Q000235:genetics / Q000378:metabolism; D001419:Bacteria / Q000235:genetics / Q000378:metabolism; D056804:Biofuels; D019149:Bioreactors / Q000382:microbiology*; D059014:High-Throughput Nucleotide Sequencing; D055432:Metabolomics / Q000379:methods*; D056186:Metagenomics / Q000379:methods*; D008697:Methane / Q000378:metabolism; D059013:Microbial Consortia / Q000502:physiology*; D013431:Sulfates / Q000378:metabolism; D014865:Waste Disposal, Fluid / Q000295:instrumentation / Q000379:methods*
chemical_list: D056804:Biofuels; D013431:Sulfates; D008697:Methane
keywords: Anaerobic digester; Biogas production; Metabolomics; Metagenomics; Wastewater sludge