As part of the Bavarian research project BayWater, which focuses on the use of membrane technologies for sustainable industrial water treatment, we are working with the IWC at TUM on an advanced oxidation process (AOP) based on peroxydisulfate (S2O82-). This process is intended to be used as a pre-treatment for wastewater in reverse osmosis (RO) plants, with the aim of minimizing membrane fouling. In addition to the low binding energy of peroxydisulfate (120 kJ·mol–1) and the associated high activation efficiency, peroxydisulfate offers advantages in terms of safety, storage stability and the associated costs. One way to activate and thus generate sulfate radicals from peroxydisulfate is by irradiation with light, especially in the UV range. The oxidation performance can be controlled via the optical power of the sources used in a way that minimizes fouling without damaging the membrane. For this reason, the aim is to design an AOP flow reactor using powerful UV LEDs on the basis of laboratory tests. Peroxydisulfate exhibits much higher extinction in the UVC region, which favors UVC activation. UVA LEDs, however, are significantly more energy-efficient, making them attractive from an operational standpoint. Therefore, the choice of the most suitable AOP light source should be based on experimental data. The radical-production efficiency of UV activation will be analyzed using a liquid-chromatography–based method and evaluated by the number of radicals generated per unit of energy consumed. The results will contribute to evaluating the feasibility of employing UV LEDs in AOP applications as an alternative to traditional mercury lamps.
Olaf et al. (Thu,) studied this question.