Improvement of energy recovery from cellobiose by thermophillic dark fermentative hydrogen production followed by microbial fuel cell

Abstract

The present study demonstrated the feasibility of using an integrated approach of combining dark fermentation with MFCs to maximize the energy recovery from cellulosic substrate. Thermophillic dark-H2 fermentation exhibited maximum H2 production yield of 2.92 mol mol−1 hexose equivalent with an energy recovery of 28% which was highest reported till date. The total cumulative hydrogen potential of 3799 mL L−1 with maximum rate of hydrogen production of 865 mL h−1, and lag time of 1.84 h were determined by using modified Gompertz equation. Subsequent use of acid rich effluents in two chamber MFCs generated maximum power density of 85.05 mW m−2 with an energy recovery of 2.49%. Moreover, a 75% COD removal was also achieved with a coulombic efficiency of 13% illustrating its ability for wastewater treatment. By using this integrated approach, an overall energy recovery of 30.49% was achieved demonstrating both environmental and economic sustainability of the process.