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An investigation of hydrodynamic conditions inside gas-sparged hollow fiber membrane modules Chan, Colleen C. V.

Abstract

Over the past decade, membrane filtration has emerged as a proven technology for water and wastewater treatment applications. Despite its popularity, the problem of membrane fouling remains the Achilles heel of membrane filtration. A common strategy to control membrane fouling is the use of gas sparging to prevent particle deposition on membrane surfaces. The efficiency of gas sparging for fouling control/prevention depends on the effective distribution of sparged gas bubbles and bubble-induced flow across membrane surfaces. To date, there is very limited literature available that describes this hydrodynamic condition inside the submerged hollow fiber membrane modules. The reason for this limited knowledge is the complex and transient nature of the geometry and hydrodynamics inside hollow fiber modules. The hydrodynamic conditions surrounding a hollow fiber under gas sparging, and the relationship between hydrodynamic conditions and fouling control are not well understood. This presents an obstacle to optimizing the performance of submerged hollow fiber modules with respect to energy costs associated with gas sparging. This thesis provides a comprehensive study of the hydrodynamic conditions inside a gas-sparged submerged hollow fiber membrane module, and the relationship between the observed hydrodynamic conditions and fouling control. Unlike what had been hypothesized by some, the results indicated that the hydrodynamic conditions inside a submerged hollow fiber membrane are different than those of confined tubular membrane systems. It was also observed that different types of shear profiles exist inside the membrane module, and the different types of shear conditions result in different fouling, which suggests that different mechanisms are at play in controlling particle transport near the membrane surface. This information opens the opportunity for further investigation in terms of optimization of the gas –sparging system, or other shear-generating devices that create shear conditions that offer the greatest benefit minimizing fouling, while minimizing the energy demand associated with generating these shear conditions.

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Attribution-NonCommercial-NoDerivatives 4.0 International

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