Biodegradation of pharmaceuticals in hospital wastewater by staged Moving Bed Biofilm Reactors (MBBR)

• Published in: Water research (Oxford) Vol. 83; pp. 293 - 302
• Main Authors: Casas, Mònica Escolà, Chhetri, Ravi Kumar, Ooi, Gordon, Hansen, Kamilla M.S., Litty, Klaus, Christensson, Magnus, Kragelund, Caroline, Andersen, Henrik R., Bester, Kai
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 15.10.2015
• Subjects: Bacterial Physiological Phenomena; Biodegradation; Biodegradation, Environmental; Biofilms; Biofilms - growth & development; Bioreactors; Conjugates; Continuous flow; Degradation; Degradation kinetics; Denmark; Environmental Restoration and Remediation - methods; Hospital wastewater; Hospitals; Pharmaceutical Preparations - metabolism; Pharmaceuticals; Pilot Projects; Rate constants; Reactors; Waste water; Waste Water - analysis; Water Pollutants, Chemical - metabolism; X-ray contrast media; Denmark; Biodegradation; X-ray contrast media; Conjugates; Hospital wastewater; Degradation kinetics; Pharmaceuticals
• ISSN: 0043-1354; 1879-2448
• DOI: 10.1016/j.watres.2015.06.042

Hospital wastewater represents a significant input of pharmaceuticals into municipal wastewater. As Moving Bed Biofilm Reactors (MBBRs) appear to remove organic micro-pollutants, hospital wastewater was treated with a pilot plant consisting of three MBBRs in series. The removal of pharmaceuticals was studied in two experiments: 1) A batch experiment where pharmaceuticals were spiked to each reactor and 2) a continuous flow experiment at native concentrations. DOC removal, nitrification as well as removal of pharmaceuticals (including X-ray contrast media, β-blockers, analgesics and antibiotics) occurred mainly in the first reactor. In the batch experiment most of the compounds followed a single first-order kinetics degradation function, giving degradation rate constants ranged from 5.77 × 10−3 to 4.07 h−1, from −5.53 × 10−3 to 9.24 × 10−1 h−1 and from 1.83 × 10−3 to 2.42 × 10−1 h−1 for first, second and third reactor respectively. Generally, the highest removal rate constants were found in the first reactor while the lowest were found in the third one. This order was inverted for most compounds, when the removal rate constants were normalized to biomass, indicating that the last tank had the most effective biofilms. In the batch experiment, 21 out of 26 compounds were assessed to be degraded with more than 20% within the MBBR train. In the continuous flow experiment the measured removal rates were lower than those estimated from the batch experiments. [Display omitted] •Three MBBR reactors in series were applied to hospital wastewater.•Degradation of pharmaceuticals mainly coincided with COD and nitrogen removal.•The biomass in the last MBBR was the smallest but most active removing pharmaceuticals.•X-ray contrast media were removed better than in activated sludge treatment.•De-conjugation of pharmaceuticals altered the removal of pharmaceutical-in continuous operation.