title: Occurrence and elimination of antibiotics at four sewage treatment plants in the Pearl River Delta (PRD), South China.
abstract: In this paper, the occurrence and elimination of eight selected antibiotics mainly for human use, including chloramphenicol, fluoroquinolone, sulfonamide and macrolide groups, were investigated at four sewage treatment plants (STPs) in the Pearl River Delta (PRD), South China. The most frequently detected antibiotics in the present study were ofloxacin, norfloxacin, roxithromycin, erythromycin-H(2)O (the main degradation product of erythromycin) and sulfamethoxazole. The concentrations of these compounds in raw influents and final effluents at the four STPs ranged from 10 to 1978 ngL(-1) and from 9 to 2054 ngL(-1), respectively. The other analytes were detected only in a few samples from the four STPs. Antibiotics could not be eliminated completely at the four STPs, with the highest elimination efficiency reaching to 81%. Analysis of the dissolved daily mass flow showed that fluoroquinolones were mostly eliminated from the sewage, and high concentrations of these compounds were found in secondary sludge. Therefore, it can be concluded that the observed elimination of fluoroquinolones in the STPs was due to their sorption to the sludge, but not biodegradation. Macrolides, especially erythromycin-H(2)O, were stable in sewage during the treatment process, and in fact even higher concentrations were found in the final effluents than in the raw sewages. Sulfamethoxazole was also found in raw influent and final effluent, indicating that it could withstand different treatment processes in the STPs. Remarkable differences in the daily environmental loads (the sum of the amounts in the final effluent and sludge) of the five most frequently detected antibiotic compounds were found in the range of 0.5-828 g at the four STPs.
authors.affiliation: State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China.
authors.forename: Weihai
authors.initials: W
authors.lastname: Xu
authors.forename: Gan
authors.initials: G
authors.lastname: Zhang
authors.forename: Xiangdong
authors.initials: X
authors.lastname: Li
authors.forename: Shichun
authors.initials: S
authors.lastname: Zou
authors.forename: Ping
authors.initials: P
authors.lastname: Li
authors.forename: Zhaohui
authors.initials: Z
authors.lastname: Hu
authors.forename: Jun
authors.initials: J
authors.lastname: Li
mesh_terms: D000900:Anti-Bacterial Agents / Q000032:analysis* / Q000302:isolation & purification; D002681:China; D052918:Environmental Restoration and Remediation / Q000379:methods*; D012722:Sewage; D014874:Water Pollutants, Chemical / Q000032:analysis* / Q000302:isolation & purification
chemical_list: D000900:Anti-Bacterial Agents; D012722:Sewage; D014874:Water Pollutants, Chemical