University of Toronto, Department of Civil Engineering, 35 St. George St., Toronto, ON M5S 1A4, Canada.
Water Res. 2010 Feb;44(3):845-53. doi: 10.1016/j.watres.2009.09.004. Epub 2009 Sep 8.
The disinfection effectiveness of three organic N-chloramines (chlorinated amino acids and peptides) on the bacteria Escherichia coli (E. coli) was investigated, including a more detailed study into the pH dependency of the disinfection effectiveness of N-chloroglycine. The organic N-chloramines were prepared by combining sodium hypochlorite with each amino acid or peptide (glycine, Ala-Ala and Arg-Gly-Asp-Ser), at a N:Cl molar ratio of 1:0.4, and then used to treat E. coli suspensions for 180 min. No evidence of inactivation was observed at pH 8.1 for any of the tested organic N-chloramines. At pH 6.0 and 6.9, E. coli inactivation with N-chloroglycine was characterized by an initial lag phase, during which little or no measurable inactivation occurred, followed by a pseudo-first-order inactivation. This is in accordance with other results in the literature and supports the two step microbial inactivation mechanism proposed by some authors. Inactivation rate coefficients (Chick-Watson and lag coefficients) were calculated by fitting the experimental data with the Rennecker-Mariñas model. pH-dependent inactivation kinetics were observed, with faster inactivation rates occurring at lower pH values, when temperature and chlorine-to-nitrogen ratio where kept constant. N-chloroglycine was determined to be the only contributor to the inactivation process in these experiments. The free chlorine contribution was considered to be negligible in all experiments due to its very low concentration. As well, given that the anionic form of N-chloroglycine is expected to be the single predominant species over the tested pH range, changes in residual N-chloroglycine speciation could not be responsible for the observed pH-dependency of E. coli inactivation. However, while pH stress was considered as a possible synergistic factor, no significant effect of pH stress on E. coli viability was observed at the tested pH levels.
研究了三种有机 N-氯胺（氯代氨基酸和肽）对细菌大肠杆菌（E. coli）的消毒效果，其中包括更详细地研究 N-氯代甘氨酸消毒效果的 pH 依赖性。将次氯酸钠与每种氨基酸或肽（甘氨酸、Ala-Ala 和 Arg-Gly-Asp-Ser）以 N:Cl 摩尔比 1:0.4 结合，制备有机 N-氯胺，然后用其处理大肠杆菌悬浮液 180 分钟。在 pH 值为 8.1 时，对于测试的任何有机 N-氯胺，都没有证据表明存在失活现象。在 pH 值为 6.0 和 6.9 时，N-氯代甘氨酸对大肠杆菌的失活表现为初始迟滞期，在此期间几乎没有或没有可测量的失活，然后是伪一级失活。这与文献中的其他结果一致，并支持一些作者提出的两步微生物失活机制。通过将实验数据拟合到 Rennecker-Mariñas 模型中，计算了灭活率系数（Chick-Watson 和迟滞系数）。观察到 pH 值依赖性失活动力学，在较低的 pH 值下，当温度和氯与氮的比例保持不变时，失活速率更快。在这些实验中，确定 N-氯代甘氨酸是失活过程的唯一贡献者。由于其浓度非常低，因此认为自由氯的贡献在所有实验中都可以忽略不计。此外，由于预计在测试的 pH 范围内，N-氯代甘氨酸的阴离子形式将是唯一主要存在的物种，因此观察到的大肠杆菌失活动力学的 pH 依赖性不能归因于残留 N-氯代甘氨酸形态的变化。然而，尽管认为 pH 应激是一个可能的协同因素，但在测试的 pH 水平下，未观察到 pH 应激对大肠杆菌活力的显著影响。
