New Brunswick Scientific Co., Inc.

Robert D Mohler

Shaul Reuveny

Lee B Eppstein

A method and an apparatus for controlling the concentration of oxygen and pH of a medium during a bioreaction process in a vessel. The method and apparatus are particularly adapted to a fermentation process. A dissolved oxygen sensor generates a signal corresponding to the pH of the medium and a dissolved oxygen sensor generates a signal corresponding to the dissolved oxygen in the medium. A valve mechanism selectively applies air, N.sub.2, O.sub.2 and CO.sub.2 to the medium. A controller produces a control signal for controlling the operation of the valve means so that a substantially fixed volume of gas consisting of one or more of air, CO.sub.2, N.sub.2 and O.sub.2 are added to the fermenting medium during a period of time. The controller determines in response to the dissolved oxygen and pH signals, the amount of CO.sub.2, O.sub.2 and/or N.sub.2 required to effect dissolved oxygen and pH correction. The controller further adjusts these determined values to compensate for the displacement of the CO.sub.2 added. As a result, the effect of the CO.sub.2 correction on the dissolved oxygen is substantially minimized.

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Bridgewater, NJ, United States of America

Robert D Mohler