Optimization, metabolic pathways modeling and scale-up estimative of an AnSBBR applied to biohydrogen production by co-digestion of vinasse and molasses

Abstract

This study investigated the application of an AnSBBR in biohydrogen production process from the co-digestion of vinasse and molasses. Process performance indicators were evaluated using the organic matter removal efficiency, molar hydrogen yield, productivity and composition of the biogas. The influence of influent composition and concentration, feeding mode (batch/fed batch), need for micronutrient supplementation and inoculum pretreatment were evaluated. Kinetic modeling of the metabolic pathways of the conditions with the highest hydrogen productivity was performed. The results showed that the system was stable under all conditions. The best results were obtained with an influent concentration of 6000 mgCOD L−1, composition of 67–33% vinasse-molasses, without micronutrient supplementation, with inoculum heat shock pretreatment, and batch mode (13.5 molH2 m−3 d−1 with 39% H2). Increasing the percentage of the vinasse in the influent was unfavorable, but increasing the influent concentration, refraining from micronutrient supplementation and performing the inoculum heat shock pretreatment favored the performance indicators. The fitted kinetic model aided the understanding of the metabolic pathways: hydrogen is produced via acetic, butyric and valeric acids routes. Scale up estimation (performed with data of best condition) resulted in a system with 6 discontinuous reactors configured in parallel, each one with a volume of 27,297 m3. © 2016 Hydrogen Energy Publications LLC