Avoiding digester imbalance through real-time expert system control of dilution rate

Process control of anaerobic digesters is a particularly challenging problem because of the diversity of possible causes that can lead to digester imbalance. Conventional control schemes can fail in consequence of a reversal in the sign of the steady-state gain caused by some type of disturbance. In this work we present an expert system approach that takes into account the particularity of this process. The developed algorithm is demonstrated to compensate successfully for changes in the digester feed medium when simulated against a model for a continuous anaerobic digester.