Comparison of Reactor Configurations for Biogas Production from Rapeseed Straw

Xinmei Fu, Yuan Hu


To investigate the effects of reactor configurations on the anaerobic digestion performance of agricultural residue rapeseed straw, semi-continuous, one-stage, continuously stirred tank reactors (CSTR) and batch, two-stage, leach bed-upflow anaerobic sludge blanket (UASB) reactors were operated at the same hydraulic retention time (HRT) (30 days) and target organic loading rate (OLR) (3.0 gVS/L.d). In the continuously loaded CSTR, the specific methane yields did not substantially change as the OLR increased from 1.5 gVS/L.d to 3.0 gVS/L.d during the four periods. Conversely, the specific methane yields in the batch-fed leach bed-UASB increased considerably with the increase in OLR. The leach bed reactor contributed 75% of the total yield, while the UASB reactor contributed only 25% of the total yield. The total specific methane yields were 108 mL/gVS and 160 mL/gVS for the leach bed-UASB and CSTR, respectively, while the volatile solid (VS) reductions of the rapeseed straw were 27.1% and 36.6%, respectively. The results indicated that the process performance was more efficient in the CSTR than in the leach bed-UASB for the digestion of rapeseed straw. Biogas production was clearly affected by the reactor configurations.


Anaerobic digestion; Biogas; Continuously stirred tank reactor (CSTR); Leach bed-upflow anaerobic sludge blanket (UASB); Rapeseed straw

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