Removal of antibiotics and non-steroidal anti-inflammatory drugs by extended sludge age biological process

Removal of four antibiotics (sulfamethoxazole, sulfadimethoxine, sulfamethazine and trimethoprim) and four non-steroidal anti-inflammatory drugs (acetaminophen, ibuprofen, ketoprofen and naproxen) using extended sludge age biological process was investigated. The sludge age of the biological system was greater than 200 d. Hydraulic retention time of 12 h was maintained throughout the experiment. The extended sludge age biological process is able to treat pharmaceuticals with good and steady removal efficiencies: 64–93% removal for antibiotics over 1–5 μg L⁻¹ influent concentrations and 94% to complete removal for acetaminophen and ibuprofen with a wide range of influent concentrations 1–100 μg L⁻¹. For ketoprofen and naproxen the removal efficiencies are 79–96% over a range of 1–15 μg L⁻¹ influent concentrations. The removal efficiency decreases with increasing initial concentrations for all target compounds except for ibuprofen. This indicates that the initial influent concentration is an important parameter for the studies of fate of pharmaceuticals. The amount of bio-mass and size of the reactor required to achieve good and steady removal efficiencies for known influent pharmaceutical concentrations are also suggested in this study.