Correlation between conductivity and liquid hold-up for a multi-segment industrial foam probe for fermentation

• Published in: Biochemical engineering journal 2004-07, Vol.19 (3), p.199-210
• Main Authors: Varley, J, Boyd, J.W.R, Gallagher, S, Brown, A.K, Dodd, P.W
• Format: Article
• Language: English
• Subjects: Biological and medical sciences; Biotechnology; Conductivity; Fermentation; Foam probe; Fundamental and applied biological sciences. Psychology; Liquid hold-up
• ISSN: 1369-703X; 1873-295X
• DOI: 10.1016/j.bej.2004.02.008

In this paper we describe the use of a multi-segment conductivity probe for measuring conductivity as a function of height and time in a foam phase. Relationships between the conductivity ratio (ratio of conductivity in a foam to conductivity in the bulk liquid) and the liquid hold-up in the foam have been described previously by a number of researchers. If conductivity measurements from the multi-segment probe could be interpreted in terms of liquid hold-up in the foam this would provide valuable information about the physical nature of foam in, for example, a fermentation process, in which foams are known to have a number of adverse effects. Conductivity ratios have been determined for two multi-segment probes (one measures over a rectangular section of foam central to a cylindrical vessel, whilst the other measures over a disk like slice of foam). Liquid hold-up was measured using a specially designed column, which allows selected sections of foam (corresponding to segments on the foam probe) to be collected and weighed for determination of liquid content. A range of solutions and process parameters were used to generate foams with a range of structures and liquid hold-ups. At low values of liquid hold-up (