title: Semi-aerobic fermentation as a novel pre-treatment to obtain VFA and increase methane yield from primary sludge.
abstract: There is a growing trend to consider organic wastes as potential sources of renewable energy and value-add products. Fermentation products have emerged as attractive value-add option due to relative easy production and broad application range. However, pre-fermentation and extraction of soluble products may impact down-stream treatment processes, particularly energy recovery by anaerobic digestion. This paper investigates primary sludge pre-fermentation at different temperatures (20, 37, 55, and 70°C), treatment times (12, 24, 48, and 72h), and oxygen availability (semi-aerobic, anaerobic); and its impact on anaerobic digestion. Pre-fermentation at 20 and 37°C succeeded for VFA production with acetate and propionate being major products. Pre-fermentation at 37, 55, and 70°C resulted in higher solubilisation yield but it reduced sludge methane potential by 20%. Under semi-aerobic conditions, pre-fermentation allowed both VFA recovery (43gCODVFAkg(-1)VS) and improved methane potential. The latter phenomenon was linked to fungi that colonised the sludge top layer during pre-fermentation.
authors.affiliation: Centre for Solid Waste Bioprocessing, Schools of Civil and Chemical Engineering, The University of Queensland, St. Lucia Campus, 4072 QLD, Australia.
authors.forename: M
authors.initials: M
authors.lastname: Peces
authors.affiliation: Advanced Water Management Centre, The University of Queensland, St. Lucia Campus, 4072 QLD, Australia. Electronic address: s.astals@awmc.uq.edu.au.
authors.forename: S
authors.initials: S
authors.lastname: Astals
authors.affiliation: Centre for Solid Waste Bioprocessing, Schools of Civil and Chemical Engineering, The University of Queensland, St. Lucia Campus, 4072 QLD, Australia.
authors.forename: W P
authors.initials: WP
authors.lastname: Clarke
authors.affiliation: Advanced Water Management Centre, The University of Queensland, St. Lucia Campus, 4072 QLD, Australia.
authors.forename: P D
authors.initials: PD
authors.lastname: Jensen
mesh_terms: D000085:Acetates / Q000378:metabolism; D000332:Aerobiosis; D057919:Biological Oxygen Demand Analysis; D005232:Fatty Acids, Volatile / Q000378:metabolism*; D005285:Fermentation; D008697:Methane / Q000096:biosynthesis*; D011422:Propionates / Q000378:metabolism; D012722:Sewage / Q000382:microbiology*; D012995:Solubility
chemical_list: D000085:Acetates; D005232:Fatty Acids, Volatile; D011422:Propionates; D012722:Sewage; D008697:Methane
keywords: Anaerobic digestion; Fermentation; Fungi; Sewage sludge; Temperature