The synergistic fouling of ceramic membranes by particles and natural organic matter fractions using different surface waters in South Africa

The synergistic fouling of ceramic membranes by particles and natural organic matter fractions using different surface waters in South Africa

Moyo, Welldone (University of South Africa)
Chaukura, Nhamo (University of South Africa; Sol Plaatje University)
Motsa, Machawe M. (University of South Africa)
Mthombeni, Nomcebo H. (University of South Africa)
Msagati, Titus A.M. (University of South Africa)
Mamba, Bhekie B. (University of South Africa)
Heijman, Sebastiaan (TU Delft Sanitary Engineering)
Nkambule, Thabo T.I. (University of South Africa)

2021

This study demonstrates the fundamental differences in fouling development and mechanisms of unfiltered and 0.45 µm pre-filtered water samples on ceramic membranes. Robust characterization of the feed waters was conducted using gravimetric analysis, optical methods and modeling techniques. UV₂₅₄ removal and suspended solids (SS) for the unfiltered samples presented a strong correlation (R² = 0.87). Further, SS exhibited strong correlations with fluorescent fractions (R² = 0.82; 0.81 and 0.74 for C1; C2 and C3, respectively). This observation confirmed the significance of inorganic particles in the development of a combined fouling layer with fluorescent organic components. The fouling development rate for water sampled from Plattenburg Bay (PL) was higher than the rest of the 0.45 µm pre-filtered samples. This was attributed to the low conductivity (175 µS.m^-1) of the water sample, translating to a low ionic strength environment. Samples collected from Hermanus River (HL) and Lepelle River (OL) had similar SS quantity (87.6 mg/L and 88.4 mg/L, respectively), and modified fouling index (MFI) values for raw samples were 6625 and 8060 s/L², respectively, despite a very large difference in the content of organic matter (22.67 mg/L.C and 9.81 mg/L.C). This could be due to organic matter attaching onto the surface of particles and reducing the adsorption of NOM within membrane pores and/or onto the membrane active layer. This study demonstrated the extent of in situ background electrolytes, foulant concentration, foulant-foulant interactions, foulant-membrane interaction and physicochemical properties of feed stream on fouling development and mechanisms.

Fluorescent organic matter
Membrane fouling resistance
Modified fouling index
Particulate organic matter
Synergistic fouling

http://resolver.tudelft.nl/uuid:61755c8c-c1e4-4f36-a898-569ff9c57650

https://doi.org/10.22079/JMSR.2020.127635.1384

Journal of Membrane Science and Research, 7 (2), 125-137

Institutional Repository

journal article

© 2021 Welldone Moyo, Nhamo Chaukura, Machawe M. Motsa, Nomcebo H. Mthombeni, Titus A.M. Msagati, Bhekie B. Mamba, Sebastiaan Heijman, Thabo T.I. Nkambule