Model-based design of a software sensor for real-time diagnosis of the stability conditions in high-rate anaerobic reactors – Full-scale application to Internal Circulation technology

Abstract

Internal Circulation (IC) anaerobic systems are especially suitable when plant designs that involve both small footprints and high organic loading rates (>25 kg COD m−3 d−1) are required. However, given that operating anaerobic processes at high organic loads increases their vulnerability to external disturbances, real-time indicators of the stability conditions become particularly pertinent for IC reactors. This paper addresses the design and full-scale validation of a software sensor that uses only feeding flow-rate and biogas flow-rate measurements to classify the operating conditions of the reactor as “strongly”, “moderately” or “weakly” stable. A simulation-based procedure was used to design the software sensor and configure its parameters. Then, the performance of the software sensor was tested under real conditions in a full-scale IC reactor of 1679 m3 installed in a recycled paper mill (RPM).