Dark fermentative hydrogen production from cassava starch: A comprehensive evaluation of the effects of starch extrusion and enzymatic hydrolysis
Daniel Oluwagbotemi Fasheun, Ayla Sant’Ana da Silva, Ricardo Sposina Sobral Teixeira, Viridiana Santana Ferreira-Leitão
Abstract
Hydrolysis could be rate-limiting for the dark fermentative H 2 production from cassava starch (CS) due to its semicrystalline nature. Therefore, the effects of CS extrusion and enzymatic hydrolysis on improving dark fermentation (DF) were studied. Preliminary DF experiments were conducted to investigate the effects of inoculum (sludge) heat-pretreatment, which increased H 2 production from untreated-CS by over 154%. Likewise, 15 g/L starch was considered best for H 2 production. Extruded-CS presented a maximum H 2 yield of 1.58 mol H 2 /mol glucose with a 76% reduction in the fermentation adaptive phase and 43% increase in maximum H 2 productivity compared to untreated-CS. Meanwhile, extruded-CS hydrolysate presented a maximum H 2 yield of 1.8 mol H 2 /mol glucose with a 63% reduction in the fermentation adaptive phase and 18% increase in H 2 productivity. A comprehensive assessment of the H 2 yield, process time, production rate, and process simplification revealed extruded-CS as the most promising feedstock under the evaluated conditions.