title: Methanosarcinaceae and acetate-oxidizing pathways dominate in high-rate thermophilic anaerobic digestion of waste-activated sludge.
abstract: This study investigated the process of high-rate, high-temperature methanogenesis to enable very-high-volume loading during anaerobic digestion of waste-activated sludge. Reducing the hydraulic retention time (HRT) from 15 to 20 days in mesophilic digestion down to 3 days was achievable at a thermophilic temperature (55°C) with stable digester performance and methanogenic activity. A volatile solids (VS) destruction efficiency of 33 to 35% was achieved on waste-activated sludge, comparable to that obtained via mesophilic processes with low organic acid levels (<200 mg/liter chemical oxygen demand [COD]). Methane yield (VS basis) was 150 to 180 liters of CH4/kg of VS(added). According to 16S rRNA pyrotag sequencing and fluorescence in situ hybridization (FISH), the methanogenic community was dominated by members of the Methanosarcinaceae, which have a high level of metabolic capability, including acetoclastic and hydrogenotrophic methanogenesis. Loss of function at an HRT of 2 days was accompanied by a loss of the methanogens, according to pyrotag sequencing. The two acetate conversion pathways, namely, acetoclastic methanogenesis and syntrophic acetate oxidation, were quantified by stable carbon isotope ratio mass spectrometry. The results showed that the majority of methane was generated by nonacetoclastic pathways, both in the reactors and in off-line batch tests, confirming that syntrophic acetate oxidation is a key pathway at elevated temperatures. The proportion of methane due to acetate cleavage increased later in the batch, and it is likely that stable oxidation in the continuous reactor was maintained by application of the consistently low retention time.
authors: Advanced Water Management Centre, The University of Queensland, St Lucia, Queensland, Australia.
authors: Dang P
authors: DP
authors: Ho
authors: Paul D
authors: PD
authors: Jensen
authors: Damien J
authors: DJ
authors: Batstone
mesh_terms: D000085:Acetates / Q000378:metabolism*; D000693:Anaerobiosis; D058448:Biota; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D004275:DNA, Ribosomal / Q000737:chemistry / Q000235:genetics; D017019:Methanosarcinaceae / Q000145:classification / Q000302:isolation & purification* / Q000502:physiology; D010084:Oxidation-Reduction; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D017422:Sequence Analysis, DNA; D012722:Sewage / Q000382:microbiology*; D013696:Temperature
chemical_list: D000085:Acetates; D004269:DNA, Bacterial; D004275:DNA, Ribosomal; D012336:RNA, Ribosomal, 16S; D012722:Sewage
references: FEMS Microbiol Ecol. 2013 Sep;85(3):612-26
references: 23678985
references: J Hazard Mater. 2011 Mar 15;187(1-3):355-61
references: 21277081
references: Antonie Van Leeuwenhoek. 2008 Nov;94(4):593-605
references: 18791805
references: Appl Environ Microbiol. 2009 Apr;75(8):2566-72
references: 19218417
references: Arch Microbiol. 2000 Dec;174(6):415-21
references: 11195097
references: Water Sci Technol. 2009;59(5):927-34
references: 19273891
references: Appl Environ Microbiol. 1988 Jun;54(6):1457-61
references: 16347656
references: mBio. 2011 Sep 01;2(4):e00159-11
references: 21862629
references: Bioresour Technol. 2011 Nov;102(22):10266-72
references: 21967716
references: Nat Methods. 2010 May;7(5):335-6
references: 20383131
references: Appl Environ Microbiol. 2006 Apr;72(4):2942-9
references: 16598001
references: Microbiol Res. 2012 Dec 20;167(10):581-9
references: 22770715
references: Appl Environ Microbiol. 1994 Apr;60(4):1232-40
references: 7517128
references: Water Environ Res. 2003 Jul-Aug;75(4):377-80
references: 12934831
references: Water Res. 2011 Feb;45(4):1597-606
references: 21185054
references: Biotechnol Bioeng. 2009 Apr 1;102(5):1513-20
references: 18988267
references: J Bacteriol. 2006 Nov;188(22):7922-31
references: 16980466
references: Water Res. 2004 Apr;38(7):1653-62
references: 15026219
references: Water Res. 2009 Apr;43(7):1913-23
references: 19232670
references: Environ Sci Technol. 2011 Jan 15;45(2):508-13
references: 21162559
references: Microbes Environ. 2008;23(2):118-27
references: 21558697
references: Int J Syst Evol Microbiol. 2002 Jul;52(Pt 4):1361-1368
references: 12148651
references: Appl Environ Microbiol. 1997 Oct;63(10):4061-8
references: 16535717
references: J Biosci Bioeng. 2011 Jan;111(1):41-6
references: 20851673
references: ISME J. 2009 Jun;3(6):700-14
references: 19242531
references: Appl Environ Microbiol. 2006 Jul;72(7):5138-41
references: 16820524
references: Appl Environ Microbiol. 2012 Nov;78(21):7645-51
references: 22923399
references: FEMS Microbiol Lett. 2010 Aug 1;309(1):100-4
references: 20546311
references: Appl Environ Microbiol. 1997 Aug;63(8):3043-50
references: 9251192
references: Environ Sci Technol. 2002 Mar 1;36(5):1113-23
references: 11917999
references: Microbiol Rev. 1995 Mar;59(1):143-69
references: 7535888
references: J Biosci Bioeng. 2006 Oct;102(4):328-32
references: 17116580