Estimation of the respiration quotient in a bicarbonate buffered batch cell cultivation

In bicarbonate buffered media the carbon dioxide balance is affected by accumulation and therefore the RQ can not directly be calculated from gas flow and gas concentration measurements. To cope with the buffering capacity of such media a Kalman Filter was designed as a software sensor to estimate the RQ. To eliminate the role of a priori knowledge of cell and medium kinetics on the performance of the Kalman Filter all carbonate was lumped to one term. As a result only physical constants are required. A reference experiment verified the performance of the software sensor. Subsequently several experiments were performed with insect cells to show the progress of the RQ-values during cultivation.