Removing diclofenac, ranitidine, and simvastatin from a biologically-treated domestic sewage coupling the photo-Fenton process

Abstract

Diclofenac (DCF), ranitidine (RNT), and simvastatin (SVT) are emerging pollutants that occur in low concentrations (ng L^–1 to µg L^–1) in different environmental matrices. They are not completely removed in sewage treatment plants. Therefore, this work assesses the photo-Fenton process after an anaerobic–aerobic one to degrade DCF, RNT, and SVT (50 µg L^–1, each) in domestic sewage. A photoreactor (1654 mL) with 7 blacklight blue lamps (8 W) was used. Batch degradation in biologically-treated domestic sewage (pH 7.2 ± 0.3, 25 °C) was optimized by 2³ full factorial design (two lamps on, 3 mg L⁻¹ Fe(III), and 40 mg L⁻¹ H₂O₂), degrading 100% of RNT and DCF, 97.5% of SVT, and 72% mineralization in 10 min. Parallel processes (adsorption, photolysis, direct oxidation with H₂O_2, and UV/H₂O₂) were not observed. In continuous mode (72 mL min^–1, hydraulic retention time 10 min), 97%, 90%, and 68% of RNT, DFC, and SVT, respectively, were degraded, and 55% DOC removed. The combined system was relatively stable for, at least, 10 days. Capital and operating costs were estimated: US$ 11,565.00 and US$ 1.97 m^–3, respectively, being electric energy consumption responsible for up to 98% of the total operating cost.

Graphical Abstract