Contribution of temperature and photon absorption on solar photo-Fenton mediated by Fe3+-NTA for CEC removal in municipal wastewater

Abstract

Solar photo-Fenton process with ferric nitrilotriacetate has great potential for contaminant of emerging concern (CEC) removal from municipal effluents. To scale-up the process, gaining know-how about the effect of temperature and photon absorption is fundamental. This work presents for the first time an in-depth study about the effect of both variables on the reaction mechanism. To this end, imidacloprid (IMD) was selected as a surrogate CEC (100 μg/L). The experimental plan comprised two steps: (i) lab-scale experiments in simulated effluents, and (ii) experiments at pilot-scale in raceway pond reactors with actual effluents. Despite the process being photo-limited in the volumetric rate of photon absorption range of 103–413 μE/m3·s, the increase in the liquid depth from 5 to 15 cm allowed improving the treatment capacity, achieving more than 80 % of IMD removal with reaction times around 30 min. These results provide the necessary knowledge for photoreactor design and continuous flow operation.