State observation for fedbatch control of phenol degradation by Ralstonia eutropha

This paper concerns the design of a control system for fedbatch phenol degradation by Ralstonia eutropha. The control objective was to maintain the specific growth rate at a constant high value, or equivalently to regulate the phenol concentration at a constant low residual value. This objective was achieved thanks to a PI controller. The phenol concentration was recovered according to the measurement of 2-hydroxymuconic semialdehyde (denoted 2-hms) concentration derived from colour analysis and an extended Kalman filter. Experimental evaluation showed the viability of such an approach.