Regulatory influence of CO_2 supplementation on fermentative hydrogen production process

摘要

This study presents an approach to enhance fermentative biohydrogen (H_2) production by improving the system buffering capacity through utilization of CO_2 generated from syngas. The experimental data substantiates the positive impact of CO_2 sparging on H_2 production process. Various CO_2 sparging times viz., 30, 60 and 120 s were evaluated on H_2 production and substrate degradation. Based on the optimum sparging time (60 s), experiments were further performed to study the influence of pH microenvironment (5, 6 and 7) on the process efficiency. Further the influence of periodic CO_2 sparging was also evaluated. Experimental data visualized a marked improvement on the overall process performance based on H_2 production and substrate degradation after sparging CO_2. Carbonic acid upon association/dissociation forms bicarbonates in the system. Alkaline condition helps to build up buffering nature, which resist fluctuations in pH even at higher VFA concentra-tions. Substrate degradation was effective during intermittent sparging at neutral condi-tions. CO_2 sparging directly effecting the bulk liquid environment of the system improves buffering nature which indirectly helps to maintain favorable microenvironment for bio-hydrogen production process.