A filtration model for prediction of local flux distribution and optimization of submerged hollow fiber membrane module

Abstract

IntroductionThe submerged membrane filtration has been increasingly used in membrane bioreactor and wastewater treatment processes in recent years. 1,2 In particular, the submerged hollow fiber membrane systems have gained more popularity than either flat-sheet or tubular membrane modules due to lower cost in fabrication and energy saving in operation. 3,4 However, it is very difficult to control the hydrodynamics of such systems owning to the Page 2 of 45 AIChE Journal AIChE JournalThis article is protected by copyright. All rights reserved.Revised manuscript AIChE-15-16842R2 for submission to AIChE Journal 3 non-uniform local flux distribution along the hollow fiber membrane. 5 As a result, hollow fibers may be more prone to fouling and require more frequent washing and cleaning. 6 Recently, a number of studies on modeling and optimization of the submerged hollow fiber membrane module have been carried out to alleviate membrane fouling and increase filtration efficiency. Chang and Fane 7 developed a mathematic model for submerged hollow fiber filtration under constant flux operating mode by combining Hagen-Poiseuille equation with the concept of critical flux. In this study, the effects of fiber characteristics (length, radius and membrane resistance) on local flux distribution along the fiber were investigated. Chang et al. 8 further reported an improved model using the cake filtration theory developed by Petsev et al. In addition, Lee et al. 12 developed a quantitative method to determine the major fouling during drinking water production under various conditions through combining three different fouling mechanisms such as standard blocking, complete blocking and cake formation. Similarly, by examining pressure drop cross the membrane and cake separately, Kinčl et al. 13 developed a fundamental mathematical analysis for local flux distribution along the hollow fiber with compressible cake formation. To achieve maximum energy balance coupled with the application of exponential model to predict the permeate flux of hollow fiber ultrafiltration membrane. The simulated results showed that the effect of operating pressure on permeate flux is more significant than that of feed concentration.Especially, Kim et al. 16 described a perturbation approach of the Navier-Stokes and continuity equations to investigate the effect of membrane length and hydraulic resistance on the steady-state laminar flow of the fluid in the fiber lumen. It indicated that the flow velocity in fiber lumen represents the exponential variation along the axial direction.Although these models provide valuable insight into the filtration behavior under various operating conditions, they only focused on the overall separation performance rather than local filtration behavior. In addition, as the simulated results have been barely proved by AIChE JournalThis article is protected by copyright. All rights reserved.Revised manuscript AIChE-15-16842R2 for submission to AIChE Journal 5 experimental tests, the applications of these theoretical works are...

Characteristics and fouling propensity of polysaccharides in the presence of different monovalent ions

“…behavior of polysacchrides also depends on the imposed flux 50 and other water chemistry such as pH.…”

Three‐dimensional simulation of the time‐dependent fluid flow and fouling behavior in an industrial hollow fiber membrane module

“…Unlike the studies focused on the single membrane system which describe the fluid flow and fouling behavior in the porelevel 44,45 or membrane-level, 48,49 the present study for the first time reveals the time and spatial variations of flux distribution of the entire module. The first mode is the axial adjustment along each fiber and the second mode is the minimization of the diversity of flux distributions among fibers.…”

“…As the foulants accumulate on the membrane surface, both of the non-uniformities of flux axial and radial distributions will get largely relieved. Unlike the studies focused on the single membrane system which describe the fluid flow and fouling behavior in the porelevel 44,45 or membrane-level, 48,49 the present study for the first time reveals the time and spatial variations of flux distribution of the entire module.…”

Pressure driven inside feed (PDI) hollow fibre filtration: Optimizing the geometry and operating parameters

“…In the literature there are a few attempts to analyse the influences of geometry of HF module design on the overall filtration behaviours mostly with regard to crossflow operation. Agreement has been reached that a shorter length fibre with larger lumen diameter is desirable so as to increase the filtration throughput per unit membrane area [11][12][13][14][15][16]. Long fibres with small inner diameters will generate large differences in local flux and leads to a rapid increase in transmembrane pressure [13,14].…”

“…Long fibres with small inner diameters will generate large differences in local flux and leads to a rapid increase in transmembrane pressure [13,14]. Additionally, any increase in fibre length beyond a certain value will lead to more non-uniform local flux distribution and severe membrane fouling [16]. Moreover, the negative effect of having longer fibres will be even worse at high module packing (low void fraction) because the filtration flux will decrease dramatically and filtration behaviour will occur preferentially at the capped end [17][18][19].…”