State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing, 210023, China.
State Key Laboratory of Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai, 200092, China.
Chemosphere. 2022 Dec;309(Pt 1):136577. doi: 10.1016/j.chemosphere.2022.136577. Epub 2022 Sep 22.
Boiling is a widely adopted household tap water treatment method because of its ability to inactivate chlorine-resistant pathogenic bacteria, and to reduce certain groups of disinfection byproducts (DBPs). From a more comprehensive point of view, this study revisited the effect of boiling on four groups of 17 aliphatic DBPs and six groups of 44 aromatic DBPs in both simulated chlorinated and chloraminated tap water samples, with a special focus on the changes of total organic halogen (TOX) and cytotoxicity. Results showed that the concentrations of aliphatic DBPs substantially decreased during boiling via volatilization (trihalomethanes and chloral hydrate) and hydrolysis (haloacetamides) in chlorinated and chloraminated tap water samples. The concentrations of aromatic DBPs during boiling generally followed an increasing trend due to decarboxylation of polycarboxylic precursors in chlorinated tap water samples, and showed a first increasing and then decreasing trend in chloraminated tap water samples. A sharp decreasing of TOX occurred in the heating process of tap water samples from room temperature to 100 °C, and a relatively gentle decreasing was kept in the prolonged boiling process till 5 min. The most abundant DBP group in the tap water samples without boiling was trihalomethanes, and was replaced by haloacetic acids with boiling for 5 min. Continuous boiling for 5 min substantially reduced the cytotoxicity of chlorinated and chloraminated water samples by 52.6% and 21.3%, respectively. Reduction of cytotoxicity matched well with the reduction of TOCl (r = 0.907, P < 0.01), TOBr (r = 0.885, P < 0.01) and TOX (r = 0.905, P < 0.01), suggesting that the cytotoxicity reduction during boiling was mainly ascribed to the reduction of halogenated DBPs. Therefore, boiling of tap water to 100 °C was strongly recommended to reduce the potential health risks induced by tap water ingestion.
煮沸是一种广泛采用的家庭自来水处理方法，因为它能够灭活抗氯病原体，并减少某些组别的消毒副产物（DBPs）。从更全面的角度来看，本研究重新考察了煮沸对模拟氯化和氯胺化自来水中的四组 17 种脂肪族 DBP 和六组 44 种芳香族 DBP 的影响，特别关注总有机卤素（TOX）和细胞毒性的变化。结果表明，在氯化和氯胺化自来水中，煮沸通过挥发（三卤甲烷和水合氯醛）和水解（卤乙酰胺）导致脂肪族 DBP 浓度大幅降低。由于氯化自来水中多羧酸前体的脱羧作用，煮沸过程中芳香族 DBP 浓度通常呈上升趋势，而在氯胺化自来水中呈先上升后下降的趋势。自来水中 TOX 在从室温加热到 100°C 的过程中急剧下降，在延长煮沸过程中直至 5 分钟保持相对温和的下降。未煮沸的自来水中最丰富的 DBP 组是三卤甲烷，煮沸 5 分钟后被卤乙酸取代。连续煮沸 5 分钟可使氯化和氯胺化水样的细胞毒性分别降低 52.6%和 21.3%。细胞毒性的降低与 TOCl（r=0.907，P<0.01）、TOBr（r=0.885，P<0.01）和 TOX（r=0.905，P<0.01）的降低相吻合，表明煮沸过程中细胞毒性的降低主要归因于卤代 DBP 的减少。因此，强烈建议将自来水煮沸至 100°C，以降低因摄入自来水而导致的潜在健康风险。
