An improved method for controlling foams produced within bioreactors

A novel approach is described for monitoring fermentation foams created by Pseudomonas sp. This approach uses a new foam sensor that provides a continuous on-line I IL conductance measurement of the foam as a function of the height of foam within the vessel headspace. The conductance signal in the foam is dependent on the liquid hold-up and the ionic concentration of the liquid contained in the foam structure. By using correlations from the literature, the liquid fraction in the foam can be estimated from the conductance measured in the foam. The effect of changing the process conditions during the fermentation has been investigated. The results from these fermentations have been used to develop a preliminary neural network model for this particular process that will be used to provide a future prediction of the foaming behaviour inside the vessel. This prediction will eventually be used to formulate an appropriate foam control strategy for this fermentation process. The aim of the new foam control system will be to minimize antifoam additions (if required) and enable enhanced control of the foam via changes in the process variables.