Fault diagnosis of anaerobic digester system using nonlinear state estimator: application to India’s largest dairy unit

The complex biochemical processes along with uncertain load disturbances in anaerobic digesters (AD) lead to frequent upsets and poor performance of the overall system. Several techniques have been proposed in the literature to address fault detection and isolation in the anaerobic digester. However, these methods do not provide information about the internal states of the system and use expert and heuristics for fault isolation. In this work, we first developed a first principle based model of the AD unit at one of India’s largest dairy and validated using experimental results. Subsequently, we used this model to demonstrate the applicability of nonlinear state estimation approaches for fault diagnosis.