Pilot-scale removal of microcontaminants by solar-driven photo-Fenton in treated municipal effluents: selection of operating variables based on lab-scale experiments

Abstract This study aimed to assess the removal efficiency of microcontaminants (namely: acetaminophen, diclofenac, carbamazepine, caffeine, sulfamethoxazole, trimethoprim) spiked in water by solar-driven photo-Fenton using Fe:Ethylenediamine-N, N′-disuccinic acid (1:1), focusing especially on improving operating parameters. These parameters were first studied at lab scale (1 - 4 L): (i) Fe3+ concentration; (ii) liquid depth; (iii) water matrix (natural water and real municipal wastewater treatment plant effluent). The best conditions were then evaluated outdoors under natural radiation in a pilot-scale solar photoreactor (90 L) treating real municipal wastewater treatment plant effluent evaluated by HPLC/QqLIT-MS. Diclofenac was the most efficiently degraded at lab scale and it was shown that the light pathlength did not affect the degradation rate but deeper liquid enables more treatment capacity. Fe:EDDS at 1:1 and iron concentration at 0.054 mM was sufficient for MC removal efficiency up to 97%. All microcontaminants (46 microcontaminants were detected) were efficiently removed in the pilot-scale under the best conditions determined at lab scale. Therefore, a well-designed, simple, low-volume and low-cost lab-scale photoreactor and a selected mixture of microcontaminants at close to real concentrations would enable selection of the operating parameters of a large solar photo-Fenton application.