Online sauter diameter measurement of air bubbles and oil drops in stirred bioreactors by using hough transform

Abstract

Industrial production of important fermentation products such as enzymes, antibiotics, and aroma compounds, amongst others, involves a multiphase dispersion. Therefore, it is important to determine the influence of the bioreactor operational parameters (stirring speed, impeller type, power drawn, etc.) under which the culture achieves the highest yields. The automatic on-line analysis of multiphase dispersions occurring in microbial cultures in mechanically stirred bioreactors, presents a number of important problems for image acquisition and segmentation, including heterogeneous transparency of moving objects of interest and background, blurring, overlapping and artifacts. In this work, a Hough transform based method was implemented and tested. Results were compared with those obtained manually by the expert. We concluded that using this method, the evaluation of size distributions of air bubbles and oil drops in a mechanically stirred bioreactor was performed in a more efficient and less time-consuming way than others semiautomatic or manual methods. © Springer-Verlag 2004.