Lactate plays a fundamental role in carboxylic chain elongation.
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Bio-hydrogen recovery through n-butyrate production.
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Modified ADM1 simulated the self-regulation between species.
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MCMC is a robust parameter estimation method for fermentation processes.
Abstract
This study aimed to develop and compare different Anaerobic Digestion Model no. 1 extensions to represent hydrogen and n-butyrate synthesis (ADM-CE). For developed models' calibration, experimental data were gathered from a previous study investigating dark fermentative H2 production from cheese whey in mesophilic batch mode. The Markov chain Monte Carlo method was applied to determine free parameters values under limited iterations until reaching convergence assisted by Geweke's diagnostic. Each developed model considered different aspects of investigation such as: pH inhibition, phase transfer limitation mechanisms, MCMC sample sizes and approaches, competitive inhibition, hydrolysis step and chain elongation biomass discretization. The estimation of all parameters showed upright MCMC. Among the proposed models, the ADM-CE could predict about 73% accumulated H2 and 87% of total n-butyrate obtained experimentally. In effect, the consideration of self-regulation mechanism between fermentative organisms represents a possibility not only for H2 recovery, but also a high prospect for n-butyrate improvement.
