Multi-membrane module for gas–liquid contact: Development of a methodology for side-stream ozone injection system applications

Abstract

This work proposes an alternative methodology to scale-up a tube-in-tube gas–liquid contacting membrane module by developing a full-scale multi-membrane module. A novel hybrid CFD-analytical model, previously developed to predict mass transfer coefficients and bubble dispersion of a bubbly flow in a tube-in-tube membrane module, is used to simulate the gas bubble dispersion into the water and predict the ozone-water mass transfer coefficient, the interfacial area and gas holdup of the concept membrane contacting module. The hydrodynamics and mass transfer phenomena within the multi-membrane module were investigated, aiming for its application in industrial side-stream ozone injection systems for the disinfection and resistant pollutant removal steps of freshwater/wastewater treatment processes. The study demonstrated that the module effectively dispersed bubbles into the liquid phase, resulting in homogenized ozonated water for every module design and inlet type proposed. The multi-membrane concept module generated the same order of magnitude of interfacial area (44 m⁻¹ and 128 m⁻¹ for 8 and 40 membranes, respectively) compared to standard gas–liquid contactors (from 1 m⁻¹ to 77 m⁻¹) while operating at the lower bounds of the range of gas holdup values for these standard contactors $($$($0.7 % and 2.4 % for 8 and 40 membranes, respectively; whereas the conventional contactors remained within 1.5 % to 5.8 %). Consequently, the investigated module promoted an effective use of the injected gas. In addition, the deep comprehension of the gas–liquid mass transfer and flow behavior in membrane modules acquired through the proposed methodology enabled the optimization of multi-membrane gas–liquid contacting modules for industrial applications.