Characteristics of immobilized yeast reactors producing ethanol from glucose

The evolutionary performance of up flow reactors are affected by the cell immobilization matrix and the matrix particle size distribution. Higher productivities are obtained using a low-density brick with a particle size of ca. 400-1400 mum. A medium condition favoring growth quickly leads to large biomass gradients within the reactors and, eventually, reductions in average productivities due to bed plugging. These systems can be accurately modelled using Monod kinetics when dispersion and the biomass gradient are considered. The productivity was apparently not controlled by substrate diffusion in these cases.