title: Anaerobic digestion of food waste - Effect of recirculation and temperature on performance and microbiology.
abstract: Recirculation of digestate was investigated as a strategy to dilute the food waste before feeding to anaerobic digesters, and its effects on microbial community structure and performance were studied. Two anaerobic digesters with digestate recirculation were operated at 37 °C (MD + R) and 55 °C (TD + R) and compared to two additional digesters without digestate recirculation operated at the same temperatures (MD and TD). The MD + R digester demonstrated quite stable and similar performance to the MD digester in terms of the methane yield (around 480 mL CH4 per gVSadded). In both MD and MD + R Methanosaeta was the dominant archaea. However, the bacterial community structure was significantly different in the two digesters. Firmicutes dominated in the MD + R, while Chloroflexi was the dominant phylum in the MD. Regarding the thermophilic digesters, the TD + R showed the lowest methane yield (401 mL CH4 per gVSadded) and accumulation of VFAs. In contrast to the mesophilic digesters, the microbial communities in the thermophilic digesters were rather similar, consisting mainly of the phyla Firmicutes, Thermotoga, Synergistetes and the hydrogenotrophic methanogen Methanothermobacter. The impact of ammonia inhibition was different depending on the digesters configurations and operating temperatures.
authors.affiliation: Department of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, P. O. Box 5003, N-1432 Ås, Norway.
authors.forename: Mirzaman
authors.initials: M
authors.lastname: Zamanzadeh
authors.affiliation: Department of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, P. O. Box 5003, N-1432 Ås, Norway.
authors.forename: Live H
authors.initials: LH
authors.lastname: Hagen
authors.affiliation: NIBIO, Norwegian Institute of Bioeconomy Research, P.O. Box 115, N-1431 Ås, Norway.
authors.forename: Kine
authors.initials: K
authors.lastname: Svensson
authors.affiliation: NIBIO, Norwegian Institute of Bioeconomy Research, P.O. Box 115, N-1431 Ås, Norway.
authors.forename: Roar
authors.initials: R
authors.lastname: Linjordet
authors.affiliation: Department of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, P. O. Box 5003, N-1432 Ås, Norway. Electronic address: svein.horn@nmbu.no.
authors.forename: Svein J
authors.initials: SJ
authors.lastname: Horn
mesh_terms: D000693:Anaerobiosis; D001105:Archaea; D019149:Bioreactors / Q000382:microbiology*; D008697:Methane; D013696:Temperature
chemical_list: D008697:Methane
keywords: Ammonia; Biofuel; Biogas; Biomethane; Digestate recirculation; Microbial community