Continuous thermophilic biohydrogen production in packed bed reactor

摘要

The present research work deals with the performance of packed bed reactor for continuous H_2 production using cane molasses as a carbon source. Maximum H_2 production rate of 1.7 L L~(-1) h~(-1) was observed at a dilution rate and recycle ratio of 0.8 h~(-1) and 0.6, respectively which was corresponding to the lowest NADH/NAD~+ ratio. This suggests that the utilization of NADH pool for H_2 and metabolite production might lead to decrement in NADH/NAD~+ ratio. Thus NADH/NAD~+ ratio show inverse relation with hydrogen production. The substrate degradation kinetics was investigated as a function of flow rate considering the external film diffusion model. At a flow rate of 245 mL h~(-1) the contribution of external film mass transfer coefficient and first order substrate degradation constant were 55.4% and 44.6% respectively. Recycle ratio of 0.6 improved the hydrogen production rates by 9%. The viable cell count was directly proportional to the recycle ratio (within the range 0.1-0.6). Taguchi design showed the significant influence of the feed pH on continuous H_2 production followed by dilution rate and recycle ratio. Thus environmentally friendly and cheaper solid matrix like coconut coir could be efficiently used for thermophilic continuous hydrogen production.