Integrative advanced oxidation and biofiltration for treating pharmaceuticals in wastewater

Advanced oxidation of active pharmaceutical ingredients (APIs) in wastewater produces transformation products (TPs) that are often more biodegradable than the parent compounds. Secondary effluent from a wastewater treatment plant was treated using UV-based advanced oxidation (LPUV/H₂O₂ and MPUV/NO₃) followed by biological aerated filtration (BAF), and different APIs and their transformation products were monitored. The advanced oxidation processes degraded the APIs by 55-87% (LPUV/H₂O₂) and 58-95% (MPUV/NO₃), while minor loss of APIs was achieved in the downstream BAF system. Eleven TPs were detected following oxidation of carbamazepine (5) and iopromide (6); three key TPs were biodegraded in the BAF system. The other TPs remained relatively constant in the BAF. The decrease in UV absorbance (UVA₂₅₄) of the effluent in the BAF system was linearly correlated to the degradation of the APIs (for the MPUV/NO₃-BAF), and can be applied to monitor the biotransformation of APIs in biological-based systems.