Toxicological assessment of hospital wastewater in different treatment processes.

This study surveyed the hospital wastewater characters focusing on antibiotic contamination in seven hospitals in Bangkok. It detected 19 antibiotics of which the high-frequent detection were quinolones such as ofloxacin + levofloxacin, norfloxacin, ciprofloxacin including sulfamethoxazole. Norfloxacin and ciprofloxacin appeared the highest concentrations of 12.11 and 9.60 μg/L, respectively. Most antibiotic concentrations in the wastewaters of the studied hospitals gave a good correlation (r 2  = 0.77-0.99) to the amount of usage. In this study, batch acute toxicity tests were performed to assess the toxicity of hospital wastewater on mixed liquor, freshwater algae (Chlorella vulgaris and Scenedesmus quadricauda), and microcrustacean (Moina macrocopa). The hospital wastewaters could inhibit the mixed liquor growth and gave similar toxic levels among test species: algae and microcrustacean (9.81-13.63 and 2.62-3.09 TU, respectively). The conventional activated sludge (CAS) and rotating biological contactor (RBC) could remove fluoroquinolones and tetracycline via biomass adsorption. After treatment, most of treatment could reduce the toxicity. Nevertheless, the effluent gave slight toxicity on some test species which might be caused from chlorination and a common toxicant (NH3-N).