Thermal activation of persulfates for wastewater depollution on pilot scale solar equipment

摘要

Thermal activation of new oxidant chemicals like Persulfate (PS) has recently gained attention in driving advanced oxidation processes (AOP) for a number of applications. On the other hand, addressing energy demand with carbon free and sustainable energy solutions represents an asset for new technologies in the modern society. This paper then investigates on the removal of pharmaceuticals residues in wastewater (WW), conducted with PS advanced oxidation reactions on a solar thermal pilot equipment. Indoor preliminary investigations on small scale laboratory experimentations show how increasing temperature has a direct positive impact on pollutants degradations rate (k(app) value ranging from 0.4.10(-3) s(-1) at ambient to 10.4.10(-3) s at 75 degrees C). However, after an experimental screening methodology, 65 degrees C and 200 mu M appear as the appropriate target temperature and PS oxidant dosage to cope with both activation of PS oxidant and degradation of ten target micropollutants typically found in WW stream. Outdoor experimentations on the solar pilot equipment were conducted according to a batch running mode at a treatment capacity scale of a cubic meter. 95% pollutant removal rate is achieved within 2 h once the temperature has raised up to the target value (65 degrees C) in the bulk treated WW effluent. Series of treatment cycles under the natural dayight period demonstrate the reproducibility of the performance. As an early step result of the process optimization approach, heat recovery demonstration on the pilot equipment improves significantly the energetic balance over the now innovative thermal solar water treatment.