Document Type : Research Paper
Nanotechnology and Water Sustainability (NanoWS) Research Unit, College of Science, Engineering and Technology
Nanotechnology and Water Sustainability Research Unit, UNISA
Nanotechnology and Water Sustainability Research Unit
Department of Civil and Chemical Engineering
College of Science, Engineering and Technology
Technical University of Delft
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.
• Fouling development and mechanism is demonstrated using ‘real’ water samples.
• Contribution of inorganic particles on the synergistic fouling is demonstrated.
• Physico-chemical characteristics of feed water on fouling development are described.