Operating control for enrichment of hydrogen-producing bacteria from anaerobic sludge and kinetic analysis for vinasse inhibition

Abstract

This study was aimed to evaluate bio-hydrogen production from sugarcane vinasse by the mixed culture enriched through controlling operational parameters in an Anaerobic Sequencing Batch Reactor (AnSBR), as well as determining the effect of the sugarcane vinasse concentration on hydrogen production and the critical kinetic analysis. The Volumetric Hydrogen Production Rate (VHPR) of 28.1 mL H2/L h at the substrate concentration of 10 g COD/L was obtained in biomass enriching step. In batch tests, the increase in substrate concentration ranging from 1.70 to 11.60 g COD/L caused an increase in Hydrogen Yield (HY); however, it had a negative effect on HY at the substrate concentrations of higher than 11.60 g COD/L. The maximum HY in terms of initial Chemical Oxygen Demand (CODi) of 58.41 mL H2/g CODi was obtained at the substrate concentration of 11.60 g COD/L. Additionally, Andrew and Han-Levenspiel models were employed to model the hydrogen production rate (R) in case of different chemical oxygen demand (COD) concentrations of vinasse. According to the comparison made between the correlation coefficient values of the fittings using the aforementioned models, the Han-Levenspiel model could be considered as a better model to describe the substrate inhibition effect. The carbohydrate removal efficiency was superior to 90% at substrate concentrations less than 16.80 g COD/L.