Fig. 1.

Photo of the dynamic membrane aeration (DMA) concept (left) in contrast to a conventional rotor-stator-system/membrane aeration setup (right). On the DMA, the membrane tubing is wrapped vertically around the rotor arms, which are arranged radially on the rotor shaft at the top and bottom of the bioreactor. The shaft is located in the center of the reactor and performs an oscillating rotary movement driven by an external servo motor. The flow around the membrane tubing is initiated by the relative motion between the membrane and the liquid. The two concentric rings provide membrane gas supply and removal. On the conventional membrane aeration setup, the tubing is wrapped vertically on a stator with a concentric, steadily rotating anchor stirrer