multiple cycles (Fig. 2B). The total gas production over the
three cycles with SSI-Syn was 110 10 mL per batch based on
duplicate reactors, with an average of 79 2% of hydrogen and
10 2% methane (Table 2), and a maximum current density of
1.15 0.05 A/m3. In contrast, gas production with FEI-Syn
varied between 80 and 159 mL (average 97 31 mL) and contained
76 6% of hydrogen. The proportion of methane in the
gas produced for FEI-Syn varied between 1 to 45%, with an
average of 21 16% over the first five cycles with the duplicate
reactors.
The use of the actual fermentation effluents produced
comparable or slightly lower amounts of gas per batch cycle
than when the reactor was fed with synthetic effluent
(Table 2). There was 105 17 mL of gas produced using the
cellobiose fermentation effluent, and 97 16 mL with corn
stover lignocellulose fermentation effluent. The percent of
hydrogen in the gas, however, declined compared to the
synthetic effluent. There was 69 4% H2 in the gas from the
cellobiose effluent, and 69 6% H2 with the lignocellulose