Non-uniform distribution of adsorptive fouling along hollow fiber membrane: Characterization and quantification

Abstract

Abstract Non-uniform distribution of local flux along the hollow fiber (HF) membrane length poses a high risk of partially overloaded flux to exacerbate membrane fouling. In-depth analysis of its effect on fouling is critical to the design of membrane geometry (e.g. fiber length, inner and outer diameters). This study focused on HF membrane adsorptive fouling by soluble organic substances under the influence of local flux distribution. The non-uniform distribution of adsorbed foulant was experimentally observed via fluorescence and contact angle measurements. An HF-Thomas model was then developed to describe the dynamic adsorption process (free/adsorbed concentration as a function of time), by incorporating Langmuir and Linear adsorption kinetics into the hydrodynamics of the HF membrane lumen. The model fitting was found to be effective in determining the HF membrane adsorption parameters (equilibrium and rate constants) of typical polysaccharide, protein, and humic acid model compounds. Extended simulation was conducted using the HF-Thomas model to explore the impacts of local flux distribution on foulant mass transfer and adsorptive fouling distribution under different scenarios of membrane geometry. The non-uniformity of flux and adsorption was found to be markedly amplified by a comprehensive dimensionless factor, λl (which derives from fiber length, inner and outer diameters, and intrinsic filtration resistance). Therefore, λl may qualify as a critical parameter for HF membrane design. According to the results of this study, λl