title: Indigenous microbial capability in solid manure residues to start-up solid-phase anaerobic digesters.
abstract: Batch solid-phase anaerobic digestion is a technology for sustainable on-farm treatment of solid residues, but is an emerging technology that is yet to be optimised with respect to start-up and inoculation. In the present study, spent bedding from two piggeries (site A and B) were batch digested at total solids (TS) concentration of 5, 10 and 20% at mesophilic (37°C) and thermophilic (55°C) temperatures, without adding an external inoculum. The results showed that the indigenous microbial community present in spent bedding was able to recover the full methane potential of the bedding (140±5 and 227±6L CH4kgVSfed-1for site A and B, respectively), but longer treatment times were required than for digestion with an added external inoculum. Nonetheless, at high solid loadings (i.e. TS level>10%), the digestion performance was affected by chemical inhibition due to ammonia and/or humic acid. Thermophilic temperatures did not influence digestion performance but did increase start-up failure risk. Further, inoculation of residues from the batch digestion to subsequent batch enhanced start-up and achieved full methane potential recovery of the bedding. Inoculation with liquid residue (leachate) was preferred over a solid residue, to preserve treatment capacity for fresh substrate. Overall, the study highlighted that indigenous microbial community in the solid manure residue was capable of recovering full methane potential and that solid-phase digestion was ultimately limited by chemical inhibition rather than lack of suitable microbial community.
authors.affiliation: Advanced Water Management Centre, The University of Queensland, St Lucia, QLD 4072, Australia.
authors.forename: S D
authors.initials: SD
authors.lastname: Yap
authors.affiliation: Advanced Water Management Centre, The University of Queensland, St Lucia, QLD 4072, Australia.
authors.forename: S
authors.initials: S
authors.lastname: Astals
authors.affiliation: Advanced Water Management Centre, The University of Queensland, St Lucia, QLD 4072, Australia.
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.
authors.forename: D J
authors.initials: DJ
authors.lastname: Batstone
authors.affiliation: Advanced Water Management Centre, The University of Queensland, St Lucia, QLD 4072, Australia. Electronic address: s.tait@awmc.uq.edu.au.
authors.forename: S
authors.initials: S
authors.lastname: Tait
mesh_terms: D000693:Anaerobiosis; D019149:Bioreactors; D004063:Digestion; D008372:Manure; D008697:Methane
chemical_list: D008372:Manure; D008697:Methane
keywords: Anaerobic digestion; Biological inhibition; Inoculum; Manure; Microbial community; Straw