In continuous reactors, fresh media is continuously added and bioreactor fluid is continuously removed. As a result, cells continuously receive fresh medium and products and waste products and cells are continuously removed for processing. The reactor can thus be operated for long periods of time without having to be shut down.
Continuous reactors can be many times more productive than batch reactors.
This is partly due to the fact that the reactor does not have to be shut down as regularly and also due to the fact that the growth rate of the bacteria in the reactor can be more easily controlled and optimized. In addition, cells can also be immobilized in continuous reactors, to prevent their removal and thus further increase the productivity of these reactors. The configuration of a typical well-mixed continuous reactor is shown in the above figure. The agitation may be provided by an impeller or by the motion of the liquid phase created by the rising gas bubbles. In aerobic systems, oxygen is supplied to cells via air sparging.