Improving MFI-UF constant flux to more accurately predict particulate fouling in RO systems
Quantifying the effect of membrane surface porosity
M.B.M. Abunada (TU Delft - Sanitary Engineering, IHE Delft Institute for Water Education)
N. Dhakal (IHE Delft Institute for Water Education, TU Delft - Sanitary Engineering)
William Z. Andyar (IHE Delft Institute for Water Education)
Pamela Ajok (IHE Delft Institute for Water Education)
Herman Smit (PWN Waterleidingbedrijf Noord-Holland)
Noreddine Ghaffour (King Abdullah University of Science and Technology)
Jan C. Schippers (IHE Delft Institute for Water Education)
M.D. Kennedy (IHE Delft Institute for Water Education, TU Delft - Sanitary Engineering)
More Info
expand_more
Other than for strictly personal use, it is not permitted to download, forward or distribute the text or part of it, without the consent of the author(s) and/or copyright holder(s), unless the work is under an open content license such as Creative Commons.
Abstract
This study aimed to quantify the effect of membrane surface porosity on particulate fouling predicted by the MFI-UF method at constant flux. Firstly, the surface porosity of polyethersulfone UF membranes (5–100 kDa) was determined using ultra-high resolution SEM. Thereafter, the MFI-UF was measured using suspensions of polystyrene particles (75 nm), which were pre-washed to remove surfactant and particle fractions smaller than the pores of MFI-UF membranes, thus ensuring complete retention of particles during MFI-UF measurements. Consequently, the MFI-UF values of washed polystyrene particle suspensions were independent of the pore size and depended only on the surface porosity of MFI-UF membrane. The results showed that the membrane surface porosity decreased with MWCO from 10.5% (100 kDa) to 0.6% (5 kDa), and consequently the MFI-UF increased from 3700 to 8700 s/L2, respectively. This increase in MFI-UF was attributed to the non-uniform distribution of membrane pores, which is exacerbated as surface porosity decreases. Consequently, preliminary correction factors of 0.4–1.0 were proposed for MFI-UF measured with UF membranes in the range 5–100 kDa. Finally, the surface porosity correction was applied to predict particulate fouling in a full-scale RO plant. However, additional research is required to establish correction factors for different types of feed water.
help_outline