title: Distribution, fate and risk assessment of antibiotics in sewage treatment plants in Hong Kong, South China.
abstract: Occurrence, removal, consumption and environmental risks of sixteen antibiotics were investigated in several sewage treatment plants (STPs) featuring different treatment levels in Hong Kong, China. Cefalexin, ofloxacin and erythromycin-H(2)O were predominant with concentrations of 1020-5640, 142-7900 and 243-4740 ng/L in influent, respectively; their mass loads were comparable to levels reported in urban regions in China and were at the high end of the range reported for western countries. The target antibiotics behaved differently depending on the treatment level employed at the STPs and relatively higher removal efficiencies (>70%) were observed for cefalexin, cefotaxime, amoxicillin, sulfamethoxazole and chloramphenicol during secondary treatment. ß-lactams were especially susceptible to removal via the activated sludge process while macrolides were recalcitrant (<20%) in the dissolved phase. Two fluoroquinolones, ofloxacin (4%) and norfloxacin (52%), differed greatly in their removal efficiencies, probably because of disparities in their pK(a) values which resulted in different sorption behaviour in sludge. Overall antibiotic consumption in Hong Kong was back-calculated based on influent mass flows and compared with available prescription and usage data. This model was verified by a good approximation of 82% and 141% to the predicted consumption of total ofloxacin, but a less accurate estimate was obtained for erythromycin usage. Risk assessment indicated that algae are susceptible to the environmental concentrations of amoxicillin as well as the mixture of the nine detected antibiotics in receiving surface waters.
authors: State Key Laboratory in Marine Pollution, City University of Hong Kong, 83 Tat Chee Avenue, Kowloon, Hong Kong, China.
authors: H W
authors: HW
authors: Leung
authors: T B
authors: TB
authors: Minh
authors: M B
authors: MB
authors: Murphy
authors: James C W
authors: JC
authors: Lam
authors: M K
authors: MK
authors: So
authors: Michael
authors: M
authors: Martin
authors: Paul K S
authors: PK
authors: Lam
authors: B J
authors: BJ
authors: Richardson
mesh_terms: D000658:Amoxicillin / Q000032:analysis; D000900:Anti-Bacterial Agents / Q000032:analysis*; D002506:Cephalexin / Q000032:analysis; D002681:China; D002701:Chloramphenicol / Q000032:analysis; D004363:Drug Utilization / Q000706:statistics & numerical data; D004784:Environmental Monitoring; D004917:Erythromycin / Q000032:analysis; D024841:Fluoroquinolones / Q000032:analysis; D006723:Hong Kong; D006801:Humans; D018942:Macrolides / Q000032:analysis; D015242:Ofloxacin / Q000032:analysis; D018570:Risk Assessment; D012722:Sewage / Q000737:chemistry; D014865:Waste Disposal, Fluid / Q000706:statistics & numerical data*; D014874:Water Pollutants, Chemical / Q000032:analysis*; D014877:Water Pollution, Chemical / Q000706:statistics & numerical data*; D047090:beta-Lactams / Q000032:analysis
chemical_list: D000900:Anti-Bacterial Agents; D024841:Fluoroquinolones; D018942:Macrolides; D012722:Sewage; D014874:Water Pollutants, Chemical; D047090:beta-Lactams; D004917:Erythromycin; D002701:Chloramphenicol; D000658:Amoxicillin; D015242:Ofloxacin; D002506:Cephalexin