Conceptual design of a dynamic turbospacer for efficient low pressure membrane filtration

S.M. Ali, A. Qamar, S. Phuntsho, N. Ghaffour, J.S. Vrouwenvelder, H.K. Shon
Desalination, Volume 496, p. 114712, (2020)

Keywords

Feed spacer design, Membrane filtration, 3D printing, DNS, Fouling, Optical coherence tomography (OCT)

Abstract

​This study presented a conceptual design of a novel dynamic turbospacer to enhance the performance of a low pressure membrane filtration process. It consists of ladder type filaments and a series of microturbine networks within the filament cells. The rotation of the turbines leads to the formation of turbulence in the feed channel that prevents foulants accumulation. Direct numerical simulation (DNS) was conducted to characterize the fluid flow behaviors of the feed channel for the proposed turbospacer and compared with a standard symmetric non-woven feed spacer. Further, their performances were investigated for a low pressure ultrafiltration (UF) process in a lab-scale experimental setup using 2.8 mm thick 3D printed prototypes of the turbospacer and the standard spacer. Experiments for the proof of this concept were conducted at 173 mL/min and 250 mL/min feed solution inlet velocity when Reynolds number of the flow is 160 and 230 respectively. Substantial reductions in fouling effects using the turbospacer was confirmed by the in-situ Optical Coherence Tomography (OCT) scans of the fouling cake layer accumulated over the membrane during the filtration of seawater with high fouling potential. The proposed turbospacer also lowered the average pressure drop by 4 times and enhanced the specific permeate flux by more than 3 times at 173 mL/min inlet flowratre. At the same operating condition, the specific energy consumption for the turbospacer was found about 2.5 folds lower than the standard spacer.

Code

DOI:10.1016/j.desal.2020.114712

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