A consolidated bio-processing of ethanol from cassava pulp accompanied by hydrogen production

Abstract

A biphasic fermentation approach was undertaken for the production of ethanol and hydrogen from cassava pulp. The glucose generated by co-culture of Clostridium thermocellum and Thermoanaerobacterium aotearoense was 13.65±0.45 g L(-1), which was 1.75 and 1.17-fold greater than that produced by mono-cultures of C. thermocellum and T. aotearoense, respectively. The accumulated glucose could be utilised rapidly by subsequently inoculated Saccharomyces cerevisiae. An inoculum ratio of 1:1, a thermophilic fermentation of 84 h, and a pulp concentration of 4% proved optimal for ethanol production, fermentation efficiency, and productivity. With these conditions, the ethanol level reached 8.83±0.31 g L(-1) with a fermentation efficiency of 64.95±2.71%. Hydrogen production of 4.06 mmol by the co-culture system was 1.54 and 2.09-fold greater than that produced by mono-cultures of C. thermocellum and T. aotearoense, respectively. This sequential co-culture approach provided a consolidated bio-processing means to produce ethanol and hydrogen from cassava pulp.