Comparison of ceramic and polymeric membrane permeability and fouling using surface water

Abstract

The trans membrane pressure (TMP) increase at a constant flux of 150 L m −2 h −1 due to membrane fouling by direct filtration with lake water is investigated for four ceramic (Al 2O 3, ZrO 2, TiO 2, SiC) and a PES/PVP polymeric microfiltration membrane(s). The membrane structures and compositions are characterised with permporometry (pore size, porosity) and XPS. The TiO 2 and SiC membrane have a 5 and 24 times larger average pore size than expected based on supplier information. The TMP increase rate due to fouling inversely follows the measured pore size. Reversible fouling decreases in the order of polymeric ≈ Al 2O 3 ≈ ZrO 2 > TiO 2 > SiC, and for irreversible fouling polymeric > ZrO 2 > Al 2O 3 > TiO 2 > SiC. Removal of non purgeable organic carbon (NPOC) is around 30% for the ceramic membranes, and 13–25% for the polymeric membrane. The reversible NPOC load decreases in the following order (Al 2O 3 > (ZrO 2 ≈ TiO 2)) ≈ SiC > polymeric. The higher degree of fouling on the polymeric membrane is partly due to its lower volume/area ratio, compared to ceramic membranes. Mass balance analysis shows that 85 ± 8% of the NPOC is accounted for. Thus, the used soaking method (pH 12 NaOH, >1 h) does not fully remove the NPOC, suggesting that a more aggressive cleaning solution should be used.