The air-phase mass tranfer resistance in the lumen of a hollow fiber at low air flow

Abstract

Removal of volatile organic compounds (VOCs) from water/wastewater by membrane air stripping (MAS) was studied using microporous polypropylene hollow fiber membrane modules. Chloroform was used as model organic compound. The mass transfer of organic compound from feed solution to air stream was studied with liquid cross-flow on the shell side and airflow in the lumen of hollow fibers. The Graetz numbers for airflows in the lumen of the fibers in this study ranged from 3.1×10 −3 to 6.9×10 −3. For such low Graetz numbers, the widely used Lévéque’s [Annales de Mines 12 (13/14) (1928) 201] model was found to be inapplicable. An alternative model is presented to predict the mass transfer resistance. This model was found to be useful, particularly when the airflow rate on the lumen side of the hollow fiber is very low.