Department of Civil Engineering, The University of Hong Kong, Hong Kong Special Administrative Region.
Water Res. 2013 Jun 1;47(9):2970-82. doi: 10.1016/j.watres.2013.03.001. Epub 2013 Mar 27.
The chlorination behaviours of 12 antibiotics belonging to six classes at environmentally relevant concentrations were systematically examined under typical conditions relevant to municipal wastewater chlorination. Cefotaxime, cefalexin, ampicillin and tetracycline were completely removed under all three initial free chlorine dosages (5 mg/L, 10 mg/L, and 15 mg/L). The removal efficiencies of sulphamethoxazole, sulphadiazine, roxithromycin, anhydro-erythromycin, ofloxacin, and trimethoprim were closely correlated to the residual free chlorine concentration, and no further significant mass removal was observed after the residual free chlorine concentration decreased to less than ≈ 0.75 mg/L. Ammonia plays a critical role during chlorination because of its competition with antibiotics for free chlorine to form combined chlorine, which reacts slowly with these antibiotics. Except for norfloxacin and ciprofloxacin, the removal behaviours of the 10 other target antibiotics under ammonia nitrogen concentrations ranging from 2 to 15 mg/L were characterised by a rapid initial removal rate upon contact with free chlorine during the first 5 s-1 min (depending on the specific antibiotic and ammonia nitrogen concentration) and then a much slower removal rate. Free chlorine was responsible for the reaction with antibiotics during the rapid stage (first 5 s-1 min), whereas combined chlorine reacted with antibiotics in the subsequent slow stage. Combined chlorine can remove norfloxacin and ciprofloxacin at a relatively faster rate. The presence of suspended solids at 30 mg/L slightly decreased the antibiotic removal rate. The kinetic rate constants decreased by 2.1-13.9%, while the half-lives increased by 2.0-15.0% compared to those of a 0 mg/L suspended solid for the target antibiotics.
在与城市污水氯化典型条件相关的环境相关浓度下，系统地研究了 12 种属于六类的抗生素的氯化行为。在所有三个初始游离氯剂量（5mg/L、10mg/L 和 15mg/L）下，头孢噻肟、头孢氨苄、氨苄西林和四环素均被完全去除。磺胺甲恶唑、磺胺嘧啶、罗红霉素、脱水红霉素、氧氟沙星和甲氧苄啶的去除效率与剩余游离氯浓度密切相关，当剩余游离氯浓度降低至约<0.75mg/L 以下时，没有进一步的显著质量去除。由于其与抗生素竞争游离氯形成结合氯，氨在氯化过程中起着关键作用，结合氯与这些抗生素反应缓慢。除诺氟沙星和环丙沙星外，在氨氮浓度为 2-15mg/L 范围内，10 种其他目标抗生素的去除行为表现为与游离氯接触后的初始快速去除率（取决于特定抗生素和氨氮浓度），然后去除率较慢。在快速阶段（最初的 5s-1min），游离氯负责与抗生素反应，而随后的缓慢阶段，结合氯与抗生素反应。结合氯可以以相对较快的速度去除诺氟沙星和环丙沙星。30mg/L 悬浮固体的存在略微降低了抗生素的去除率。与 0mg/L 悬浮固体相比，目标抗生素的动力学速率常数降低了 2.1-13.9%，半衰期延长了 2.0-15.0%。
