antibiotics removal in biological sewage treatment plants

this study investigated the occurrence and removal of 12 antibiotics (ciprofloxacin, enrofloxacin, levofloxacin, norfloxacin, nalidixic acid, azithromycin, clarithromycin, roxithromycin, lincomycin, novobiocin, sulfamethoxazole, trimethoprim) at four sewage treatment plants (stps): two stps in kyoto, japan and two stps in beijing, china. the stps differed in design and operation conditions, utilized a variety of secondary treatment processes. the antibiotics were frequently detected in influents and effluents, and ranged from ng/l up to lower μg/l. in influent, clarithromycin (1.1–1.6 μg/l) and levofloxacin (3.6–6.8 μg/l) were detected in the highest concentration in japanese and chinese stps, respectively. the overall elimination of the antibiotics were differed between stps and ranged from negative to >90%. these data demonstrate that there are detectable levels of antibiotics are discharging from stps, and only some of these antibiotics are being removed in a significant proportion by stps. it was also observed that biological nutrient removal based sewage treatment processes (anaerobic–anoxic–oxic: a2o; and anoxic–oxic: ao) have relatively higher antibiotics removal efficiencies than oxidation ditch (od) processes.