Abstract:
Hydrogen and methane production using a two stage up-flow anaerobic sludge blanket (UASB) were investigated in this research. The first and second stages using 1 L and 1.5 L UASB reactors were designed for the hydrogen and methane production, respectively. All experiments were conducted under the room temperature (30+-3 ํC), and fixed influent pHs of 5.5 for the hydrogen production reactor and that of 7.0 for the methane production reactor. In the hydrogen production reactor, the hydrogen production under the varied hydraulic retention times (HRT) of 8 and 6 hours and organic loading rates of 6.54+-0.09, 6.70+-0.20 and 7.70+-0.24 g COD d[superscript -1] L[superscript -1][subscript reactor] were studied, while HRT in methane production was fixed 10 hours, and the ORL was dependent on the ORL of the effluent of the hydrogen production reactor. At HRT of 8 hours and OLR of 6.54+-0.09 g COD d[superscript -1] L[superscript -1][subscript reactor] the amount of hydrogen produced is 1,464.47+-22.40 mL d[superscript -1] (12.48+-1.39 mmole H[subscript 2]/g COD) COD removal is 39.69+-1.28%, and the concentrations of acetic acid, propionic acid, and butyric acid accumulated in the reactor are 12.97, 3.27 and 0.81 M, respectively, while the amount of methane produced is 2,371.00+-114.55 mL d[superscript -1] (87.62+-2.34 mmole CH[subscript 4]/g COD) COD removal is 87.91+-1.65%. At HRT of 6 hours and OLR of 7.70+-0.24 g COD d[superscript -1] L[superscript -1][subscript reactor] the amount of hydrogen produced is 1,286.76+-59.64 mL d[superscript -1] (7.38+-1.19 mmole H[subscript 2]/g COD) COD removal is 29.30+-1.09%, and the concentrations of acetic acid, propionic acid, and butyric acid accumulated in the reactor are 5.91, 3.14 and 0.06 M. respectively, while the amount of methane produced is 2,913.34+-97.37 mL d[superscript -1] (96.00+-4.04 mmole CH[subscript 4]/g COD) and COD removal is 85.76+-1.18%. At HRT of 6 hours, and OLR of 6.70+-0.20 g COD d[superscript -1] L[superscript -1][subscript reactor]] the amount of hydrogen producced is 1.802.67+-68.89 mL d[superscript -1] (21.87+-1.50 mmole H[subscript 2]/g COD) COD removal is 30.93+-0.57%, and the concentrations of acetic acid, propionic acid, and butyric acid accumulated in the reactor are 19.16, 1.51 and 0.53 M, respectively, while the amount of methane produced is 2,554.83+-98.70 mL d[superscript -1] (78.89+-4.06 mmole CH[subscript 4]/g COD) and COD removal 88.21+-0.52%.