Thermodynamic Inhibition in a Biofilm Reactor with Suspended Bacteria

We formulate a biofilm reactor model with suspended bacteria that accounts for thermodynamic growth inhibition. The reactor model is a chemostat style model consisting of a single replenished growth promoting substrate, a single reaction product, suspended bacteria, and wall attached bacteria in the form of a bacterial biofilm. We present stability results for the washout equilibrium and conduct a computational study. While stability conditions are similar to a chemostat model, we find that the steady-state concentration of the replenished substrate depends on its inflow concentration. In the computational study, we find that thermodynamic inhibition limits substrate utilization/ production both inside the biofilm and inside the aqueous phase, resulting in less suspended bacteria and a thinner biofilm.