Mathematical Modeling of Anaerobic Co-digestion of Corn Stover Hydrochar and Food Waste for Control Design Application

Abstract

Energy crisis and lignocellulose biomass waste management are the greatest issues that the world is facing today. This problem can be overcome by anaerobic digestion (AD) of lignocellulose biomass waste to produced methane and carbon dioxide. To optimize and control this process accurately, mathematical model of the process is needed. Unfortunately, modeling of AD process often results in high order differential equations with many unknown parameters, a fact that complicate controller design. In this study, lignocellulose biomass (corn stover hydrochar) obtained from hydrothermal carbonization at a temperature, residential time, and biomass/water ratio of 215 oC, 45 min and 0.115 respectively, was added to the bioreactor as a substrate inoculated with food waste and cow dung to generate biogas. Three batch processes were performed with organic loading of 0.2 m3, two part was utilized for parameter estimation and model construction while the other part for model validation. The estimation of the model parameters was based on dynamical experiments. It is satisfied employing two techniques: 4th order Runge Kutta numerical techniques and deterministic sequential quadratic programming (SQP) algorithm. Simulation of the developed mathematical model is conducted based on the different data set of the process. The biogas developed model predict the set of the experimental data for all considered process variables with high precision. Future work will entail the application of controller design in AD system.