Behavior of pharmaceuticals in UV photoreactors fed with sewage treated by anaerobic/aerobic system.

Abstract

This work has assessed the seasonal changes and the dynamics in the concentration of six pharmaceutical compounds during photolysis as a tertiary treatment of sewage previously treated by an anaerobic/aerobic system comprised by a UASB (Upflow Anaerobic Sludge Blanket) reactor and a trickling filter (TF). The target compounds were 4 antibiotics (ciprofloxacin, clindamycin, sulfamethoxazole, trimetoprime), 1 beta blocker (atenolol) and 1 anti-inflammatory (diclofenac). Six hydraulic retention times (HRT) were evaluated (5, 10, 20, 40, 80 and 160 minutes) with the intent of varying the UVC radiation doses applied to the effluent from biological treatment containing the target contaminants. The concentrations of pharmaceutical compounds in the effluent of the UASB/TF system were in agreement with the concentration levels reported in the literature. Aside from DCF, the seasonality seems to be a preponderant characteristic regarding the pharmaceutical concentration found in the effluent of biological treatment systems. The radiation dose of 117 mJ.cm-² seemed to be most suited for the photolysis application to tertiary treatment of domestic effluents. It was observed that lower UVC doses led to deconjugation of pharmaceuticals which can result in increased concentrations of target pollutants in the photo-reactor effluent.