Enhanced Degradation of Sulfamethoxazole (SMX) in Toilet Wastewater by Photo-Fenton Reactive Membrane Filtration

Pharmaceutical residuals are increasingly detected in natural waters, which made great threat to the health of the public. This study evaluated the utility of the photo-Fenton ceramic membrane filtration toward the removal and degradation of sulfamethoxazole (SMX) as a model recalcitrant micropollutant. The photo-Fenton catalyst Goethite (α-FeOOH) was coated on planar ceramic membranes as we reported previously. The removal of SMX in both simulated and real toilet wastewater were assessed by filtering the feed solutions with/without H2O2 and UV irradiation. The SMX degradation rate reached 87% and 92% respectively in the presence of UV/H2O2 for the original toilet wastewater (0.8 ± 0.05 ppb) and toilet wastewater with a spiked SMX concentration of 100 ppb. The mineralization and degradation by-products were both assessed under different degradation conditions to achieve deeper insight into the degradation mechanisms during this photo-Fenton reactive membrane filtration. Results showed that a negligible removal rate (e.g., 3%) of SMX was obtained when only filtering the feed solution through uncoated or catalyst-coated membranes. However, the removal rates of SMX were significantly increased to 67% (no H2O2) and 90% (with H2O2) under UV irradiation, respectively, confirming that photo-Fenton reactions played the key role in the degradation/mineralization process. The highest apparent quantum yield (AQY) reached up to approximately 27% when the H2O2 was 10 mmol·L−1 and UV254 intensity was 100 μW·cm−2. This study lays the groundwork for reactive membrane filtration to tackle the issues from micropollution.