Removal of pharmaceutically active compounds from hospital wastewater by ozonation pretreatment

Abstract

Hospital wastewater includes many pharmaceutically active compounds (PhACs). Since this resulted in both PhACs distribution to the environment and development of antibiotic resistance in microorganisms, on-site treatment of hospital wastewater has gained importance. In this study, the removal of 21 PhACs consisting of 12 parent compounds and 9 main metabolites from hospital wastewater by ozonation was investigated. In this context, commonly used analgesics (Paracetamol, Diclofenac, Ibuprofen, and Naproxen, 4'-Hydroxydiclofenac, 5-Hydroxydiclofenac, 1-Hydroxyibuprofen, 2-Hydroxyibuprofen, Carboxyibuprofen, (S)-O-Desmethyl naproxen) and antibiotics (Ciprofloxacin, Sulfamethoxazole, Trimethoprim, Erythromycin, Metronidazole, Clarithromycin, Azithromycin, Clindamycin, N-Acetyl-Sulfamethoxazole, Sulfamethoxazole-β-D-Glucuronide, Clindamycin sulfoxide) were selected. PhAC analyses were performed by HPLC/MS-MS. The ozonation dose was between 0.05-5.0 mg O₃/mg COD. In real hospital wastewater, many of the selected PhACs were detected and total analgesic and antibiotic were determined as 22.9 and 40.6 µg/L, respectively. The results showed that detected PhACs were completely removed at 1.5 mg O3/mg COD. Sulfamethoxazole was degraded at the lowest dose of ozone (0.05mg O3/mg COD), while Ciprofloxacin and 2-Hydroxy ibuprofen were relatively resistant to non-stoichiometric doses of ozone. The removal efficiencies of Ciprofloxacin and 2-Hydroxy ibuprofen were determined as 77% and 37%, respectively, at 0.5 mg O3/mg COD. Additionally, COD removal was 48% at 1.5 mg O3/mg COD. As a result, pre-oxidation of hospital wastewater can be an effective method for on-site pretreatment of PhACs.