RESUMO
This study presents, for the first time, the concurrent supply of the oxidants H2O2 and NaOCl in solar-driven Fenton-like processes at neutral pH with ferric nitrilotriacetate (Fe3+-NTA) for wastewater reclamation. Simultaneous Escherichia coli (E. coli) inactivation and the removal of the antibiotic sulfamethoxazole (SMX) at 50 µg/L in municipal effluents were investigated in 5-cm deep raceway pond reactors. First, the individual effects of reagent concentrations (1.47, 2.94 and 4.41 mM for H2O2; 0.134, 0.269 and 0.403 mM for NaOCl; 0.1 and 0.2 mM for Fe3+-NTA) on the economic efficiency (in terms of mass of SMX eliminated per Euro and per hour to attain complete E. coli inactivation and more than 50% of SMX removal) were considered. The highest economic efficiencies were 141 mgSMX/·h with H2O2 and 222 with NaOCl, the reaction times being 105 and 60 min, respectively. Second, a new strategy for solar photo-Fenton with the combination of the most cost-effective conditions (1.47 mM H2O2 - 0.134 mM NaOCl - 0.1 mM Fe3+-NTA) was carried out in secondary effluents from two treatment plants with different technologies. Economic efficiency was substantially affected by wastewater composition, ranging from 178 to 1131 mgSMX/·h with treatment times between 60 and 10 min, significantly improving the reported results for conventional solar photo-Fenton to date.