COD AND VFA'S CONTROL IN A TWO-PHASE ANAEROBIC DIGESTION PROCESS

In this paper, a two-phase anaerobic digestion system is considered to control the outlet concentration of both the Volatile Fatty Acids (VFA's) and the organic matter (other than the VFA's) characterized by its Chemical Oxygen Demand. The two-phase system consists of two fixed bed reactors whose dynamics are described by Partial Differential Equations. The recycle flow rates in each reactor are used as the manipulated variables to reach the control objective. The control laws designed here are decoupled and they are tested by means of simulation runs obtaining satisfactory results in spite of system input disturbances and changes on the set points.