title: Anaerobic codigestion of sewage sludge and glycerol, focusing on process kinetics, microbial dynamics and sludge dewaterability.
abstract: Anaerobic codigestion (AcoD) is a proven option to significantly boost biogas production while utilizing existing digesters and infrastructure. The aim of the present research was to conduct an exhaustive study regarding anaerobic codigestion of mixed sewage sludge and crude glycerol considering impacts on organic load, hydraulic load, process performance and microbial community. The methane potential of crude glycerol varied from 370 mL CH4·g(-1) VS to 483 mL CH4·g(-1) VS for different samples tested. The half maximal inhibitory concentration of crude glycerol was 1.01 g VS L(-1), and the primary mechanism of inhibition was through overload from rapid fermentation rather than the presence of toxic compounds in the crude glycerol. In continuous operation over 200 days, feeding glycerol at up to 2% v/v, increased organic load by up to 70% and resulted in a 50% increase in methane production. Glycerol dosing resulted in no change in apparent dewaterability, with both codigestion and control reactors returning values of 22%-24%. Members of the phylum Thermotogae emerged as a niche population during AcoD of sewage sludge and glycerol; however there was no gross change in microbial community structure and only minimal changes in diversity. AcoD did not result in synergisms between sewage sludge and crude glycerol. Actually, at dose rate up to 2% v/v glycerol dosing is still an effective strategy to increase the organic loading rate of continuous anaerobic digesters with minimal impact of the hydraulic retention time. Nonetheless, the dose rate must be managed to: (i) prevent process inhibition and (ii) ensure sufficient degradation time to produce a stable biosolids product.
authors.affiliation: Advanced Water Management Centre, The University of Queensland, St Lucia, QLD 4072, Australia. Electronic address: p.jensen@uq.edu.au.
authors.forename: P D
authors.initials: PD
authors.lastname: Jensen
authors.affiliation: Advanced Water Management Centre, The University of Queensland, St Lucia, QLD 4072, Australia; Department of Chemical Engineering, University of Barcelona, C/ Martí i Franquès, No. 1, 6th Floor, 08028 Barcelona, Spain. Electronic address: s.astals@awmc.uq.edu.au.
authors.forename: S
authors.initials: S
authors.lastname: Astals
authors.affiliation: Advanced Water Management Centre, The University of Queensland, St Lucia, QLD 4072, Australia. Electronic address: y.lu@awmc.uq.edu.au.
authors.forename: Y
authors.initials: Y
authors.lastname: Lu
authors.affiliation: Integrated Planning, Melbourne Water, 990 Latrobe Street, Docklands, Victoria 3001, Australia. Electronic address: mukundan.devadas@melbournewater.com.au.
authors.forename: M
authors.initials: M
authors.lastname: Devadas
authors.affiliation: Advanced Water Management Centre, The University of Queensland, St Lucia, QLD 4072, Australia. Electronic address: damienb@awmc.uq.edu.au.
authors.forename: D J
authors.initials: DJ
authors.lastname: Batstone
mesh_terms: D001483:Base Sequence; D056804:Biofuels; D002849:Chromatography, Gas; D017931:DNA Primers / Q000235:genetics; D005990:Glycerol / Q000378:metabolism* / Q000494:pharmacology; D006089:Gram-Negative Anaerobic Bacteria / Q000378:metabolism*; D008697:Methane / Q000096:biosynthesis*; D008969:Molecular Sequence Data; D011422:Propionates / Q000378:metabolism; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D017422:Sequence Analysis, DNA; D012722:Sewage / Q000737:chemistry / Q000382:microbiology*; D013997:Time Factors
chemical_list: D056804:Biofuels; D017931:DNA Primers; D011422:Propionates; D012336:RNA, Ribosomal, 16S; D012722:Sewage; D008697:Methane; D005990:Glycerol
keywords: Anaerobic digestion; Co-digestion; Dewaterability; Glycerine; Inhibition; Sewage sludge