Effective membrane backwash with carbon dioxide under severe fouling and operation conditions

A. Alpatova, A. Qamar, M. Al-Ghamdi, J.-G. Lee, N. Ghaffour
Journal of Membrane Science, Vol. 611, p. 118290, (2020)


Membrane fouling and cleaning, Backwash, Carbon dioxide nucleation, Kinetic of CO2 bubbles nucleation, High speed camera, Desalination


​Membrane fouling is an intrinsic deficiency common for all membrane processes. Fouling mitigation is therefore required to achieve sustainable membrane performance. Our study suggests a novel backwash concept which utilizes network of ultrafiltration interconnected membrane pores as a substrate for CO2 bubbles nucleation from a saturated COsolution which enters membrane pores from the support side. As a result, enhanced fouling removal was achieved due to additional hydrodynamic forces caused by expanded and lifted CO2 bubbles. An investigation of CO2 nucleation kinetics using a high speed camera revealed that initial CO2 nucleation rate is strongly determined by the module height and feed water type. A saturated CO2 solution backwash effectively removed bovine serum albumin (BSA) which caused both internal and external membrane fouling. A fouling reduction was also observed in BSA/seawater matrix opposite to cake layer buildup observed experiments with Milli-Q backwash. CO2 nucleation allowed to remove hydraulically irreversible fouling which was caused by transparent exopolymer particles (TEP) at pH 4 and 8. This is a promising result as TEP is biofouling precursor which tends to adsorb to a membrane surface making conventional cleaning practices inefficient. Complete transmembrane pressure recovery was achieved with a feed water containing sodium alginate and SiO2 nanoparticles with sizes compatible with membrane pores. The observed results emphasized the importance of the specific interactions in membrane/foulant/CO2 bubble triangle for a successful membrane recovery.




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