Green approach for micropollutants removal: Study of constructed wetlands as pretreatment of solar photo-Fenton catalyzed by organic fertilizers

Abstract

This study proposes a combination of vertical-flow constructed wetlands and solar photo-Fenton catalyzed by Fe-EDTA/DTPA as a greener approach to enhance micropollutant removal from simulated polluted water. In this research, two planted microcosms, one featuring Cyperus haspan and the other Phragmites australis, were examined for their effectiveness in eliminating 5 different micropollutants over varying retention times (2, 4, 7, and 14 days). The goal was to identify the most suitable conditions for an integrated treatment approach. The findings revealed that in all cases the hybrid system provided better removals than the individual treatments, above all for the more recalcitrant compounds. Notably, the combined use of C. haspan and 2 days retention time in the CW, followed by photo-Fenton applying 5 mg L−1 of iron, 50 mg L−1 of H2O2 and 20 min of irradiation achieved total removal of the micropollutants. In contrast, using only the photo-Fenton process, it needed 60 min to remove just 60% of acetamiprid, which is the most resilient of the studied substances. Constructed wetlands, however, required a longer period of contact, up to 14 days, to completely eliminate this pharmaceutical. Ultimately, this hybrid system offers a practical and adaptable solution to meet regulatory limits, tailored to the intended use or destination of the effluent. It combines cost-effectiveness, environmental friendliness, and sustainability.