US Patent 7713730 Pneumatic bioreactor

A pneumatic bioreactor having a containment vessel which includes a semi-cylindrical concavity defined by the vessel bottom. A mixing apparatus includes a rotational mixer rotatably mounted within the containment vessel about a horizontal axis. The rotational mixer has buoyancy-driven mixing cavities which are fed by a gas supply beneath the rotational mixer. The mixing apparatus extends into the semi-cylindrical concavity to substantially fill that concavity. The rotational mixer is divided into two wheels with outer paddles extending axially outwardly and inner paddles extending axially inwardly on either side of each wheel. Blades between the outer and inner paddles form impellers in the wheels to induce axial flow through the wheels in opposite directions. Stationary baffles fixed relative to the containment vessel are inclined toward the rotational mixer in the direction of rotation. The containment vessel may be of film and supported by a structural housing also having a semi-cylindrical concavity defined by the housing bottom.