Advanced oxidation processes for sulfonamide antibiotic sulfamethizole degradation: Process applicability study at ppm level and scale-down to ppb level

In this work, four advanced oxidation processes, namely heterogeneous photocatalysis, ozonation, homogeneous and heterogeneous Fenton-like treatment, were studied separately and in combinations and compared for the degradation of a widely used sulfonamide group antibiotic, sulfamethizole. The trials were carried out in a column bubble reactor operated in semi-batch and continuous mode. The applicability of the selected processes for sulfamethizole degradation was investigated at elevated concentrations (ppm level), with subsequent successful scale-down to ppb concentration level. Among studied methods, the application of ozone-based processes demonstrated the highest sulfamethizole decomposition efficiency, with 25 mu g L-1 of antibiotic being completely degraded in three minutes, even though low ozone amounts (99 mu g O-3 min(-1)) were used, comparable to those produced by germicidal lamps. The highest target compound decomposition efficiency was shown by uncoated expanded clay-assisted ozonation, where complete sulfamethizole removal was obtained within one minute. The results show that operating at elevated concentrations to determine the performance of a micropollutant degradation method is not only acceptable but also completely justified, as the scale-down study results reflect those obtained at higher concentrations quite accurately.