Improving MFI-UF constant flux to more accurately predict particulate fouling in RO systems

Improving MFI-UF constant flux to more accurately predict particulate fouling in RO systems: Quantifying the effect of membrane surface porosity

Abunada, M.B.M. (TU Delft Sanitary Engineering; IHE Delft Institute for Water Education)
Dhakal, N. (TU Delft Sanitary Engineering; IHE Delft Institute for Water Education)
Andyar, William Z. (IHE Delft Institute for Water Education)
Ajok, Pamela (IHE Delft Institute for Water Education)
Smit, Herman (PWN Drinking Water Supply Company)
Ghaffour, Noreddine (King Abdullah University of Science and Technology)
Schippers, Jan C. (IHE Delft Institute for Water Education)
Kennedy, M.D. (TU Delft Sanitary Engineering; IHE Delft Institute for Water Education)

2022

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.

Cake filtration
Membrane surface porosity
MFI-UF
Particulate fouling
Washed polystyrene particles

http://resolver.tudelft.nl/uuid:b0e01a9f-0418-4072-9ed1-5fe3f4450844

https://doi.org/10.1016/j.memsci.2022.120854

0376-7388

Journal of Membrane Science, 660

Institutional Repository

journal article

© 2022 M.B.M. Abunada, N. Dhakal, William Z. Andyar, Pamela Ajok, Herman Smit, Noreddine Ghaffour, Jan C. Schippers, M.D. Kennedy