Optimal Control Scheme on Anaerobic Processes in Biodigesters

Abstract

This paper deals with the development and test optimal control strategies that adapt their operations to confront some unstable circumstances in biological biomass processes, such as variations in the operation conditions, broadly affecting the industrial scale implementation. The complexity on biological reactions inside the process requires appropriate models that represent the phenomena in order to design and build control systems to optimize the process, and keep them away from disturbances. A two-reactor chain mass-balance model has been considered as an approximation to represent biological reactions between the different groups of bacteria immerse on anaerobic process. The model incorporates biokinetic rates, which plays a central role in the dynamical growth speed of bacteria population. An optimal control strategy is proposed to test the improvement on reaction times, compared with standard Proportional-Integral-Derivative (PID) controllers, widely used on the industry. The results show the optimal control strategies react in advance the disturbances; keeping the process on desirable operational conditions. A performance index is used to measure the advantages to use optimal control strategies. Simulations were performed on Matlab.