Kinetic Study on the Effect of Substrate and Micronutrient Inhibition during Anaerobic Fermentation of Biohydrogen

Abstract

There are several factors that influence the production of biohydrogen by dark fermentation including inoculum seeds, type and concentration of substrate, pH, temperature, presence of micronutrient and reactor configuration. Previous research has proven that the concentration of substrate and the presence of micronutrient will influence the yield and productivity of biohydrogen production. However, improvement of yield and productivity of the process can only be achieved once the system is under the optimum amount of substrate and micronutrient. Therefore, the best way to determine the effect of substrate concentration and presence of micronutrient is through kinetic study that was done using Monod model along with Andrews model. Besides that, the substrate inhibition effect also will be evaluated to determine the maximum substrate that needs to be supplied for maximum hydrogen production, and thus supplied the information for economic feasibility for fermentation process. In the meantime, the inhibition effect of adding the iron nanoparticles also had been evaluated in order to understand the interaction effect between iron nanoparticles and bacteria in term of catabolism reaction. It was found that increasing the substrate concentration more than 10 g/l will cause the inhibition to the system, in which it will slow down the reaction process and reduced the production of hydrogen. While the presence of iron NPs more than its optimum value (200 mg/l) will inhibit the bacterial growth and hence, affect the hydrogen production. For both cases, when the inhibition occurred at the respective concentration, it was found that the metabolic pathway was shifted to produce more hydrogen-consuming metabolite such as propionate acid, and thus, dropped the hydrogen production.

Biohydrogen Production from Lignocellulosic Hydrolysate: Unveiling Synergistic Impact of Substrate Concentration and Furfural Inhibition

“…In addition to the inhibitory compounds generated during the pretreatment processes; pH, substrate load, and hydrogen partial pressure are amongst others factors that have been found to have a critical effect on hydrogen production rates and yields (Chou et al 2008). Substrate concentrations above 10 g/L have been found to play a critical role in biohydrogen production as it affects the metabolic pathway (Engliman et al 2022), formulation of the microbial communities, and the intermediate production (Łukajtis et al 2018). Several studies have investigated the impact of different substrate concentrations of various feedstocks on hydrogen yield and fermentation efficiency.…”