Guneratnam, Amita Jacob; Ahern, Eoin; FitzGerald, Jamie A.; Jackson, Stephen A.; Xia, Ao; Dobson, Alan D.W.; Murphy, Jerry D.
초록
<P><B>Abstract</B></P> <P>This study investigated the operation of ex-situ biological methanation at two thermophilic temperatures (55°C and 65°C). Methane composition of 85–88% was obtained and volumetric productivities of 0.45 and 0.4LCH<SUB>4</SUB>/Lreactor were observed at 55°C and 65°C after 24h respectively. It is postulated that at 55°C the process operated as a mixed culture as the residual organic substrates in the starting inoculum were still available. These were consumed prior to the assessment at 65°C; thus the methanogens were now dependent on gaseous substrates CO<SUB>2</SUB> and H<SUB>2</SUB>. The experiment was repeated at 65°C with fresh inoculum (a mixed culture); methane composition and volumetric productivity of 92% and 0.46LCH<SUB>4</SUB>/Lreactor were achieved in 24h. <I>Methanothermobacter</I> species represent likely and resilient candidates for thermophilic biogas upgrading.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Biological methanation was assessed at 55 and 65°C with mixed culture. </LI> <LI> The efficiency were better at 65°C than 55°C. </LI> <LI> Methane content of ca. 90% was achieved at productivity of 0.45LCH<SUB>4</SUB>/Lreactor/day. </LI> <LI> Reseeding of the process is required as when inoculum ages, efficiencies decrease. </LI> <LI> <I>Methanothermobacter</I> species dominate in the ex-situ methanation community. </LI> </UL> </P>