Enhancement of Methane Production from Food Waste Using Multi-Objective Centralized Control Schemes

Food waste management and food waste-to-energy conversion have a significant impact on sustaining environmental quality and clean energy generation. Anaerobic Digestion is a widely used technique in food waste management to convert food waste into methane based on the fermentation process. Design of a control scheme for anaerobic digester to enhance the yield is a challenging task due to conflicting objectives of maximizing the methane yield with minimum retention time and minimizing the production cost of biogas. In this chapter, a multi-objective centralized control scheme is proposed for Multi-Input Multi-Output (MIMO) Mesophilic Anaerobic Digester (AD) to solve the multi-objective control problem successfully. The MIMO process is modeled by combining the Modified Hill model and the heating model. Then, Relative Gain Array (RGA) analysis is performed to identify the suitable control scheme for the MIMO process. Then different centralized control schemes are developed and compared to control methane production rate and volatile fatty acids by manipulating feed flow rate and power supplied to the heater. Then, the best-centralized control scheme is identified, and a multi-objective control problem is formulated to optimize the controller parameters of the selected centralized controller. Applying the Multi-Objective Evolutionary Algorithm (MOEA), specifically the Non-dominated Sorting Genetic algorithm-II (NSGA-II), the solution to the multi-objective control problem is achieved. Finally, the simulation studies are carried out to demonstrate the feasibility of the proposed multi-objective centralized control scheme to enhance the methane yield with minimum production cost.