PWM controlled aeration process with on-line OUR measurement

In this paper a near on-line method of Oxygen Uptake Rate measurement in a biological reactor is presented. It enables the Oxygen Uptake Rate value to be measured without disturbing the aeration process itself, assuming, that the reactor is aerated periodically using a Pulse Width Modulation control algorithm, which is effecting periods of rising and falling dissolved oxygen concentration. From the falling part of dissolved oxygen concentration the OUR can be calculated by finding the line slope coefficient of the straight line approximation. This method has been implemented and tested using a biotechnological pilot plant. In this paper the idea of method, experimental results and encountered problems are presented and discussed.