Concept of food-chain control in the bioreactor fed with a mixture of substrates

Simulation of biological processes is a complex issue. This is especially true for such biological processes as the aquaculture food chain systems in the natural environment. The quality of the final product (e.g., fish and shellfish) largely depends on the conditions in the first level of the food chain. In the modern biotechnology, the biological processes are conducted in the automated continuous flow bioreactors. This is also possible for aquaculture systems, namely, the substrate-bacteria-protozoa process, which is taken under consideration in this paper. The main contribution of the authors is the idea of using a mixture of two substrates that have different properties and are fed into the continuous flow bioreactor in order to control process course and, especially, to control the oscillatory behaviour of the food chain system. The ratio of the inlet flow rates of the two substrates is proposed as a new control variable. The analysis of the system behaviour was performed based on the simulation experiments with the use of the modified mathematical model of the food chain system. The model is an extended version of the classical models defined for the single limiting substrates. The simulation results presets the possibility of using the new control variable for control of the oscillatory behaviour of the system.