Bubbles in spacers: Direct observation of bubble behavior in spacer filled membrane channels

Air sparging is a means to prevent biofouling and scaling in hollow fibers and tubular membranes. Little is known for the case of bubbles flowing in spacer filled channels. We first demonstrate that the flow of bubbles in feed channels prevents biofouling. Then we describe a method to quantify the hydrodynamics of bubbles for various spacers, liquid and gas velocities. The bubble size at a given Reynolds number is similar for the six spacers under investigation. At low liquid velocities