Modeling the Impacts of Hydrogen Extraction on Anaerobic Fermentation Systems Using a Modified ADM1 Model

This paper presents a modified ADM1 (mADM1) model for use in assessing the influence of active dissolved H2 extraction on biogas production from anaerobic fermentation reactors, specifically in the context of high-strength brewery wastewater as the feed. The modified model adds regulation factors to account for the varying product stoichiometry of glucose degradation reactions as a function of H2 concentration in anaerobic digestion and incorporates the use of both lactate and ethanol as intermediates. The changes in the model are expected to better predict the effects of H2 removal on the production of H2 in fermentation processes. Both ADM1 and mADM1 were calibrated against experimental data from a fluidized-bed reactor containing encapsulated acidogenic-acetogenic microbial communities treating real brewery wastewater. The calibrated models were validated against another fluidized-bed reactor identical to the calibration reactor with the addition of a hollow-fiber membrane module that was used to reduce dissolved H2 concentrations in the validation reactor. It was found that ADM1 overestimated the H2 production rates of the validation reactor (117 mL/day simulated vs 16.48 mL/day experimental), whereas mADM1 was able to successfully predict fermentation, and specifically the H2 production rate (17 mL/day). The presented model is a first step toward a model that can predict the effects of dissolved H2 removal on fermentation processes.