Treatment of pharmaceutical active compounds in hospital wastewater by ozonation process

Hospital wastewater contains many pollutants including heavy metals, toxic chemicals, pharmaceuticals and microorganisms. It is mostly discharged to the domestic wastewater infrastructure and treated together with domestic wastewater in urban wastewater treatment plants (WWTPs) around the world. However, since these WWTPs are usually built on the treatment of conventional pollutants, they are inadequate for the treatment of such resistant pollutants. Therefore, pharmaceutical active ingredients are a serious problem for the environment and human health. In this context, on-site pre-oxidation of hospital wastewater is an important step in reducing these concerns.. In this study, the presence of 15 pharmaceutical active compounds and 15 metabolites including psychiatric drugs, neurostimulants, analgesics and antibiotics in real hospital wastewater, and their fate were investigated by ozonation (O3) and peroxon (O3/H2O2) treatment processes. The analysis of the selected pharmaceutical active compounds was performed by HPLC/MS-MS. The experiments were carried out in ozone doses between 0.05-5.0 mg O3/mg COD in the ozonation process, and 0.2, 0.5 mg and 1.0 mg H2O2/mg COD in the peroxone process at constant ozone dose (0.1 mg O3). According to the results of the study, total antibiotics and analgesics were determined as 22.9 and 40.6 µg/L, respectively. Detected all pharmaceutical active compounds and metabolites were completely removed at 1.5 mg O3/mg COD. Sulfamethoxazole was degraded at the lowest ozone dose (0.05 mg O3/mg COD), while ciprofloxacin and 2-hydroxy ibuprofen were relatively resistant to non-stoichiometric ozone doses. The removal efficiencies of ciprofloxacin and 2-hydroxy ibuprofen were 77% and 37% at 0.5 mg O3/mg COD, respectively. According to the results of the study, carbamazepine was removed at 99.7% at low ozone dose (0.5 mg O3/mg COD), while similar removal efficiencies for caffeine were obtained at higher ozone doses (1.5 mg O3/mg COD). For peroxon process, although carbamazepine removal efficiency increased relatively (20%), similar positive effect was not observed for caffein. Considering the oxygen ratios per mg COD for both processes, the ozonation process was more effective process for the removal of the detected pharmaceutical active compounds. Furthermore, 48% COD removal was achieved at a rate of 1.5 mg O3/mg COD in ozonation alone. In this respect, it was observed that pre-oxidation of hospital wastewater can significantly reduce both COD and pharmaceutical loads without entering treatment processes in wastewater treatment plants.