High temperature biogas reactors to treat stillage from an industrial bioethanol process: Metabolic and microbial characterization

摘要: Stillage derived from bioethanol production process is a side stream conventionally used as feed additive after cost-intensive dehydration step. From economical and ecological points of view, it also represents an appealing substrate for biogas production. In this work, we examined the biomethanization thin stillage in stirred bioreactor under thermophilic conditions (55°C). Different organic loading rates hydraulic residence times (HRTs) were tested over long period operation. Using mono-substrate, maximum rate reached was 2.1 goTS/L/day (oTS, total solid). However, with addition commercially available iron hydroxide additive, 5.9 achieved. GC-MS denaturing gradient gel electrophoresis to study metabolites microbial population dynamics within reactor different conditions. For all studied, volatile fatty acids shown give clear indication instability. Products aromatic amino acid degradation, especially phenyl acetic (PAA), detected earlier reactors even at very low rates. PAA concentration above 0.25 g/L indicated unstable performance values above0.5g/Lwerefoundtobeinhibitorytothebiogasproductioninbatchcultures.