A full-scale evaluation of the effects of different disinfection methods on the removal of contaminants of emerging concern

Most of the past studies have focused on the effects of secondary treatment processes of Wastewater Treatment Plants (WWTPs) in the removal of Contaminants of Emerging Concern (CECs). Limited data are indeed available in the scientific literature on the capability of disinfection in the reduction of CECs. The present study, conducted in collaboration with one of the largest Italian utilities, aimed at completing the knowledge about the effects on CECs due to the most common disinfection methods: peracetic acid, sand filtration followed by UV radiation and sodium hypochlorite. The study was conducted in three full-scale WWTPs, each one equipped with one of these methods. The results demonstrated a very low reduction rate in all cases. The peracetic acid disinfection showed a better removal of methamphetamine and sulfamethoxazole; when its dosage was increased in laboratory tests, an improvement was observed for lincomycin (up to 61 %) only. The chlorination provided the lowest removal efficiency. The combination of sand filtration and UV radiation exhibited a better degradation for benzoylecgonine, sulfamethoxazole, ketoprofen and trimethoprim. The environmental risk of the disinfected effluent ranged from low to medium, depending on whether it is discharged into a river or applied to soil; the agricultural reuse showed a low sanitary risk.