Modelling & Simulation of an electrochemically mediated Biofilm Reactor for Biogas upgrading


  • Marzieh Domirani
  • Gamunu Samarakoon
  • Carlos Dinamarca



MES, biofilm, anaerobic digestion, ADM-1, bio-methane, biogas, AQUASIM


In this study, we develop a mechanistic model that contributes to the application of microbial electrochemical synthesis (MES) technology for biogas upgrading. The model considered two reactor compartments- a continuous-flow stirred-tank reactor (CSTR) and an MES biofilm reactor which are coupled through a recycle loop. The modelling of biogas production (i.e. anaerobic digestion (AD) process) in the CSTR follows the most used model for biogas process modelling, ADM-1. The MES biofilm model incorporates microbially active CO2 reduction to CH4. To formulate this reduction reaction rate, the Nernst expression was incorporated as a Monod-type kinetic expression. The simulations demonstrate the basic concepts of coupling MES reactor for biogas upgrade and its limitations. According to the simulation result, maximum CH4 content of 87% is achievable with recycling ratios of 0.4 and 0.6 when the biofilm volume-specific area is equal to 0.18 m2/m3, and 0.36 m2/m3 respectively. However, the conversion of CO2 to CH4 results in increased pH and consequently CH4 production decreases by ~ 40% compared to AD-CSTR without MES. Therefore, it is essential to maintain a proper pH to prevent the inhibition of AD. The rate of the CO2 conversion to CH4 can mainly be constrained by available substrate concentration (dissolved CO2). The local potential of the cathode and the volume-specific area above 0.36 m2/m3 have minimum effects.


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