Please start the animation by pressing the start button.
A virtual image of bioreactor is seen in the figure. The aeration of the broth is being done by the sparger and the agitation is done by flat blade turbine impeller. The temperature of the reactor is controlled by the circulation of the constant temperature water in the bioreactor. The pH of the fermentation broth is automatically controlled by the controller by the addition of acid / base using the peristaltic pumps. The detailed operation of the reactor & the controllers has been explained in an independent animation experiment earlier. There are buttons for switch on/off of air in the bioreactor.
One the left hand side, there are two graphs (CL vs time & CL vs (dCL/dt + rx)). As the experiment is initiated CL vs time graphs shows some real time value of dissolved oxygen in the bioreactor. Now stop passing the air in the bioreactor by pressing the “air supply” off button. The CL (on the graph & in the bioreactor) will start dropping quickly as the supply of the air is cut off & the available dissolved oxygen is being used by the microbial population in the bioreactor. The slope dCL/dt in “air off” domain reflects the ‘r’ value of the microorganism. The biomass concentration during the air off period can measured “off line” to calculate ‘rx’ Start “air supply” by pressing the “on” button on the top right hand side before the drop in the CL is too much (Final decreased CL should be around 15% of the initial dissolved oxygen in the reactor). After resuming the air supply, the dissolved oxygen CL in the bioreactor will start increasing again. During the transient period of increase of dissolved oxygen in the bioreactor slope “dCL/dt” is calculated by click of the mouse at the intersection points of the graph (coordinates will be visible also in the rectangle bracket) and for each click a point will appear in the graph of CL vs (dCL/dt + rx). After making four such points, a line connecting all the points will be drawn. The slope of the line is (-1/KLa) and intercept will be C* From this information KLa and C* values can be established.