Removal of microcontaminants by zero-valent iron solar processes at natural pH: Water matrix and oxidant agents effect

Abstract

This work deals with microcontaminants (MCs) removal by natural solar zero-valent iron (ZVI) process at natural pH in actual matrices. Commercial ZVI microspheres were selected as ZVI source and hydrogen peroxide and persulfate were used as oxidant agents. The experimental plan comprised the evaluation of sulphates and carbonates/bicarbonates effect on process performance, the possibility of adding an iron chelate (EDDS) to take advantage of leached iron and the treatment of MCs in actual MWWTP secondary effluent. The presence of sulphates and EDDS addition did not lead to significant changes in the process efficiency, while the carbonates naturally present in natural water (458 mg/L) diminished the treatment time need to reach the decontamination goal. Finally, the treatment of a MCs mixture consisting of Atrazine, Carbendazim, Imidacloprid, and Thiamethoxam in the range of μg/L in actual MWWTP secondary effluent by solar/msZVI/H2O2 and solar/msZVI/S2O82− obtained 7 and 22% of total removal after 180 min, respectively, which indicated a moderate competitiveness of these processes with respect to other advanced oxidation processes.