Ph.D.'s Degree Program in Environmental Engineering, Faculty of Engineering, Chiang Mai University, Chiang Mai 50200, Thailand.
Graduate School, Chiang Mai University, Chiang Mai 50200, Thailand.
Int J Environ Res Public Health. 2021 Aug 27;18(17):9066. doi: 10.3390/ijerph18179066.
The formation of trihalomethanes (THMs) in natural and treated water from water supply systems is an urgent research area due to the carcinogenic risk they pose. Seasonal effects and pH have captured interest as potential factors affecting THM formation in the water supply and distribution systems. We investigated THM occurrence in the water supply chain, including raw and treated water from water treatment plants (coagulation, sedimentation, sand filtration, ClO-disinfection processes, and distribution pipelines) in the Chiang Mai municipality, particularly the educational institute area. The effects of two seasons, rainy (September-November 2019) and dry (December 2019-February 2020), acted as surrogates for the water quality profile and THM occurrence. The results showed that humic acid was the main aromatic and organic compound in all the water samples. In the raw water sample, we found a correlation between surrogate organic compounds, including SUVA and dissolved organic carbon (DOC) (R = 0.9878). Four species of THMs were detected, including chloroform, bromodichloromethane, dibromochloromethane, and bromoform. Chloroform was the dominant species among the THMs. The highest concentration of total THMs was 189.52 μg/L. The concentration of THMs tended to increase after chlorination when chlorine dioxide and organic compounds reacted in water. The effect of pH on the formation of TTHMs was also indicated during the study. TTHM concentrations trended lower with a pH ≤ 7 than with a pH ≥ 8 during the sampling periods. Finally, in terms of health concerns, the concentration of TTHMs was considered safe for consumption because it was below the standard (<1.0) of WHO's Guideline Values (GVs).
三卤甲烷（THMs）在天然和处理水中的形成是供水系统中一个紧迫的研究领域，因为它们具有致癌风险。季节性影响和 pH 值已成为影响供水和分配系统中 THM 形成的潜在因素。我们研究了供水链中的 THM 发生情况，包括来自清迈市水处理厂（混凝、沉淀、砂滤、ClO-消毒过程和配水管道）的原水和处理水，特别是教育机构区域。两个季节（2019 年 9 月至 11 月的雨季和 2019 年 12 月至 2 月的旱季）的影响可以替代水质概况和 THM 发生情况。结果表明，腐殖酸是所有水样中的主要芳香族和有机化合物。在原水样品中，我们发现替代有机化合物（包括 SUVA 和溶解有机碳（DOC）之间存在相关性（R = 0.9878）。检测到四种 THMs，包括氯仿、溴二氯甲烷、二溴氯甲烷和溴仿。氯仿是 THMs 中的主要物质。总 THMs 的最高浓度为 189.52μg/L。当水中的二氧化氯和有机化合物反应时，加氯后 THMs 的浓度趋于增加。研究还表明了 pH 值对 TTHMs 形成的影响。在采样期间，pH 值≤7 时 TTHM 浓度趋势低于 pH 值≥8 时。最后，就健康问题而言，由于 TTHMs 的浓度低于世界卫生组织（WHO）指导值（GVs）的标准（<1.0），因此认为其可以安全饮用。
