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.