Inferential Control of Microbial Batch Culture

摘要

Batch culture of Brevibacterium linens is grown on lactic acid and amino acids as substrate in a 20 liters bioreactor. During the culture growth rate is controlled according to a time varying setpoint profile. Growth rate is inferred on from exhaust gas measurements. In the present case carbon exhaust rate is used. As this variable is corrupted with noise and disturbances, a model based filter, including a simple kinetic model, is implemented. Experimental evidence shows that the filter rejects noise and disturbances to a large extend and hereby renders the growth rate estimation suitable for control purposes. The setpoint for growth rate is the input to a supervisory control routine based on the simple kinetic model. This routine determines the values of the manipulated operation conditions so that the growth rate matches the desired setpoint. As shown, this routine is inherently suitable for MISO-control, although culture temperature is the only manipulated operation condition used in the present case. The controller software was connected to the pilot plant via the MFCS/win OPC-based software interface in a comfortable and reliable way. Experimental results prove that the presented approach allows for precisely tracking time-varying growth rate setpoint profiles.