Extension of the Set of Raw Sludges used in Industrial Anaerobic Digestion Reactors Implementable in Control Schemes Using an On-line Model Parameter Identification Strategy

Abstract

This work presents a methodology that seeks to be a new standard in modeling identification in anaerobic digestion reactors. Because it is not possible to measure all variables with reliable and cost-efficient real-time methods, a specific structure composed of an asymptotic observer for the concentration of state variables; acidogenic and methanogenic bacterias, unlock the use of new types of raw sludges for industrial control and monitoring purposes. New yield parameters were included in the reduced anaerobic digestion model (ADM2) used as the core, precisely two terms in total alkalinity, to bring about the modeling of additional organic materials at inlet containing proteins or amino acids. The fermentation of these substances introduces ammonium, providing variations in the amount of alkalinity available inside the reaction. The new model is used to solve an optimization problem that calculates the parameters that best fit the dynamics of state variables with the same information taken on the experimental data. The adjustment process started with the genetic algorithm; however, to improve the performance, a novel method is proposed called step-ahead. Together, including the design of an asymptotic observer, numerical simulations demonstrate the strengths of the structure, which constitutes a significant step in paving the way further to implement feasible, cost-effective control and monitoring systems in the industry.