Coupling of photocatalytic and separation processes as a contribution to mineralization of wastewater
Résumé
We propose to investigate the effect of recovery rates ranging from 50 to 90% on rejection of selected Pharmaceutical actives compounds wastewater (PhACs) by nanofiltration (NF) and the further treatment of NF concentrate by photocatalysis. In agreement with the literature, our results indicate that the chemical properties and composition of the effluent depend on the volume reduction factor. Then, the study focuses on the photocatalytic degradation of the selected molecules. The efficiency of photocatalytic treatment according to incident radiant flux density and the volumetric reduction factor (VRF) have been done to evaluate the global TOC destruction and the degradation of each contaminant. The degradation of target molecules in the concentrate (VRF = 2) by photocatalysis ranged from 20% to 80%. However, for higher VRF, competition with organic matter and alkalinity effects led to low degradation yields. The study of the influence of incident radiant flux density on degradation rate confirmed results already obtained by the authors and, this time, generalizes them for a complex matrix. Results show that coupling photocatalysis with a membrane process seems to be a complementary processes to classical waste water treatment in order to oxidized persistent molecules.