Specification and Supervision of System Performance in Yeast Bioprocesses

Three different case studies addressing the specification of system performance and estimation of optimal cultivation policies are examined for different yeast cultivation systems. In the first case, the industrial production of baker ’s yeast in bubble columns serves as illustration of primary model conception and exemplifies task-oriented reduction of model complexity. Within this simplified model-supported framework, different optimization techniques, that maximize process productivity, are demonstrated and compared in a second case study, the invertase production with a recombinant Saccharomyces cerevisiae strain. Finally, in the third case, the integration of specific process constrains of physical nature proper of the bioprocess is demonstrated on the optimal production of the protein GAL80 with the yeast Kluyveromyces lactis

Modelling decomposition of MSW in a consolidating anaerobic reactor

A numerical model is presented based on conceptual considerations of chemical and biological reaction processes in landfills. The model enables the details of mixed-culture population dynamics and locally based multiple reaction schemes to be described as functions of the chemical and physical environmental conditions. In its current stage of development, the model is primarily used as a research tool to analyze the influence and value of various model parameters on biodegradation and landfill gas formation processes. In order to test the accuracy of the model, simulation results have been compared with experimental data obtained from a 340-day experiment on the degradation of waste within a “consolidating anaerobic reactor (CAR).” A good match with simulated results was obtained to the measurement of methane and carbon dioxide formation, as well as to the measured concentrations of sulphate and ammonium ions in the liquid phase. In particular, the experimentally observed influence of sulphate on the methane formation could be modeled taking into account interactions between sulphate-reducing and methanogenic bacteria