Carbon Dioxide Utilization for an Enhanced Biohydrogen Production of a Biomass Hydrolysate
Alma Negre Abug and Young Sook Oh
DOI : 10.3844/ajessp.2016.282.290
American Journal of Environmental Sciences
Volume 12, Issue 4
Bio-hydrogen (H2) production in a thermophilic anaerobic bioreactor with carbon dioxide (CO2) utilization at the headspace was investigated at different ratio of Biomass substrate to Microorganism (B/M). A 3 mL volume of 80% NaOH (m/v) solution was continuously hung at the headspace of the bioreactors to capture carbon dioxide. The utilization of CO2 at its headspace, proved to enhance bio H2 production. The highest Cumulative Biohydrogen Yield (CHY) of 131.81±3.47 mL-H2/gVS was measured at the ratio of 8.10 parts of biomass to 0.90 parts of Acclimatized Seed Sludge (ASS), B/M 9, while 4.17 parts of similar biomass to 0.83 parts of ASS (B/M 5) had a biohydrogen production of 90.70±16.67 mL-H2/gVS. The B/M of 6.12 parts of biomass to 0.88 parts of ASS (B/M 7) produced a CHY of 84.72±18.35 mL-H2/gVS while the control bioreactors without CO2 utilization (without and with biomass substrate) yielded a 0.06±0.035 mL-H2/gVS and a 3.27±0.78 mL-H2/gVS respectively. The mechanism of the biofermentation in this anaerobic reaction produced two possible resulting reaction; the acetogenesis of CO2 with H2 and the hydrogenotrophic methanogenesis. These reactions consumes hydrogen in the process to produce methane or acids. The presence of 80% (m/v) NaOH solution at the headspace inside the bioreactors, utilizes the CO2 producing a hydrogen-rich region in space: The highest average H2 yield of 51.83 mL-H2 after 49.1 h with B/M 9 without methane was due to carbon dioxide utilization in the bioreactors. A univariate ANOVA and Pair-wise Tukey HSD statistical analysis revealed that the CHY of B/M9 was significantly higher than the other B/Ms. The highest yield, 55.85 mL-H2/gVS obtained with the bioreactor of B/M 9 was optimum for H2 production. The results concluded that H2 production is also enhanced by CO2 utilization at the headspace.
© 2016 Alma Negre Abug and Young Sook Oh. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.