Figure 1 . Schematic of the experimental setup including the bubble column and airflow control and monitoring system.
The air sparger was comprised of a porous air stone covering ~90% of the cross-section of the column that was mounted on a cylindrical plenum. The porous air stone was fed from a 350 ml plenum, which used porous material identical to the air stone to supply pressure drop for cross-sectional uniformity of air injection. The sparger was designed to be pressurized up to 7 bar. A differential pressure transducer (PX2300-DI, OMEGA) measured the pressure drop within the line supplying the plenum. BSD depends heavily on the average pore size in a homogenous bubbly flow. The average pore size (rp ) was calculated from