EFFECT OF CO2 ABSORPTION ON THE MEASUREMENT OF CO2 EVOLUTION RATE IN AEROBIC AND ANAEROBIC CONTINUOUS CULTURES

A general and simple equation is presented to account for the effect o f CO2 absorption and the dissociation of carbonic acid in liquid on th e measurement of the CO2 evolution rate (QCO(2)) of both anaerobic and aerobic continuous cultures. For aerobic cultures the same equation a pplies to the measurement of the respiratory quotient (RQ). The deviat ion of QCO(2) and RQ, calculated from gas-phase measurements, from the ir true values can be assessed with two parameters: one accounts for t he influence of pH, resulting from dissociation of carbonic acid, the other for the influence of operating conditions. Plots are given to sh ow the influences of culture and operating conditions; they may be use d as a guideline for choosing proper operating conditions for a reliab le measurement of CO2 evolution rate and RQ value.