Software sensors to monitor the dynamics of microbial communities: Application to anaerobic digestion

A mass balance based model has been derived to represent the dynamical beha vior of the ecosystem contained in an anaerobic digester. The model conside rs two bacterial populations: acidogenic and methanogenic bacteria. It form s the basis for the design of a software sensor considering both a model of the biological system and on-line gaseous measurements. The software senso r computes the concentration of inorganic carbon and volatile fatty acids ( VFA) in the digester. Another software sensor is dedicated to the estimatio n of the bacterial biomasses. The predictions of the software sensors for a real experiment are very close to the actual off-line measurements. The so ftware sensors monitor the accumulation of VFA and thus very early detect a destabilization of the digester due to overloading. The presented methodol ogy demonstrates the usefulness of advanced monitoring techniques for an im proved understanding of the internal working of a biological system.