Micropollutant elimination by sustainable technologies: Coupling activated carbon with solar photo-Fenton as pre-oxydation step

Abstract

This study evaluates the effectiveness of coupling solar photo-Fenton (SPF) with granular activated carbon (GAC) filtration to remove three selected micropollutants (benzotriazole, carbamazepine and diclofenac) from municipal wastewater treatment plant (WWTP) effluent. SPF was first studied stand-alone at natural pH with simulated and real irradiation in raceway pond reactors (RPR) in different water matrices. The scenario with the poorest removal was the use of real WWTP effluent as water matrix; the removal achieved was 25 % of benzotriazole, 57 % of carbamazepine and up to 80 % of diclofenac (6 mg L−1 of iron, 40 mg L−1 of H2O2, 15 cm depth, 0.49 kJ L−1). In the second phase, fresh and regenerated GAC were studied in different water matrices, showing that the complex matrices had a higher influence on the regenerated GAC. Thus, the breakthrough of regenerated GAC was achieved quicker than fresh GAC. The aim of the work was to extend the GAC lifetime by a pre-oxidation process; thus, SPF was applied for 5 minutes (0.05–0.08 kJ L−1) as a first step. GAC lifetime was extended between 2 and 12 times thanks to the pre-treatment by SPF, equaling the lifetime of the regenerated GAC to the fresh one in the more complex matrix.