Tertiary treatment of urban wastewater by solar and UV-C driven advanced oxidation with peracetic acid: Effect on contaminants of emerging concern and antibiotic resistance

water and wastewater treatment so far. In the present work its possible use as tertiary treatment of urban
wastewater to effectively minimize the release into the environment of contaminants of emerging
concern (CECs) and antibiotic-resistant bacteria was investigated. Different initial PAA concentrations,
two light sources (sunlight and UV-C) and two different water matrices (groundwater (GW) and
wastewater (WW)) were studied. Low PAA doses were found to be effective in the inactivation of
antibiotic resistant Escherichia coli (AR E. coli) in GW, with the UV-C process being faster (limit of
detection (LOD) achieved for a cumulative energy (QUV) of 0.3 kJL1 with 0.2 mg PAA L1) than solar
driven one (LOD achieved at QUV ¼ 4.4 kJL1 with 0.2 mg PAA L1). Really fast inactivation rates of
indigenous AR E. coli were also observed in WW. Higher QUV and PAA initial doses were necessary to
effectively remove the three target CECs (carbamazepine (CBZ), diclofenac and sulfamethoxazole), with
CBZ being the more refractory one. In conclusion, photo-driven AOP with PAA can be effectively used as
tertiary treatment of urban wastewater but initial PAA dose should be optimized to find the best
compromise between target bacteria inactivation and CECs removal as well as to prevent scavenging
effect of PAA on hydroxyl radicals because of high PAA concentration