Degradation of macrolide antibiotics in wastewater and soil by different advanced oxidation technologies

Clarithromycin (CLR) and erythromycin (ERY) are two macrolide antibiotics globally applied for human and animal therapy. Both compounds are considered as difficult to be degraded naturally because of their continued input and very high detection in natural environment. Wastewater treatment plants (WWTP) are recognized as a relevant route for them to enter water bodies due to their constant emission via treated wastewater (TWW). But the reuse of TWW for irrigation or sewage sludge for fertilization purposes has broadened the risks for their accumulation in soil and translocation to crops, jeopardizing human and wildlife safety. Consequently, it seems essential the application of effective/robust technologies aimed to eliminate these emerging contaminants from aquatic and soil environments. In this work we have evaluated the effectivity of two advanced oxidation processes, solar photo-Fenton process mediated by Fe³⁺-EDDS and Fe³⁺-NTA as complexing agents and ozonation, in the elimination of these contaminants from wastewater and soils, respectively. In wastewater, Fe³⁺-NTA complex was more efficient for degrading CLR and ERY, probably because of the lower scavenging effect on hydroxyl radicals than that showed by EDDS. In soil, ozonation exhibited a high efficiency to remove both compounds in different soils. In general, antibiotics removal was found to be faster as decreased the organic matter content of soils (S1 > S2 > S3). Finally, the main transformation products (TPs) were monitored during remediation trials, showing the presence of 10 and 7 TPs for CLR and ERY, respectively, in wastewater experiment, whereas 1 and 2 TPs, respectively, were found during soil experiments.