Dynamic Modelling and Experimental Validation of a Solid State Fermentation Reactor

A mathematical model is presented that predicts the non-isothermal dynamical behavior of a pilot-plant Solid State Fermentation (SSF) fed-batch reactor, employed in the preparation of compost for the Agaricus bisporus mushroom cultivation. The 9-ODE first-principles lumped-parameter model describes microbial growth, substrate consumption, compost solid and liquid volumetric fractions as well as bulk temperature and air humidity. The biomass is divided into 3 broad families with different macro-kinetics: mesophilic bacteria and fungi that may inhibit the A. bisporus growth, thermophilic fungi associated to the growth selectivity of A. bisporus and thermophilic actinobacteria degrading lignocellulose. Free-convection and evaporative heat transfer are included in the energy balance. Kinetic parameters were adjusted using a sensitivity analysis. The resulting model reproduces accurately the temperature profiles of the pilot-plant SSF reactor for different initial conditions and predicted final microflora concentration ratios are within expected values.