建筑生活热水二次消毒的微生物灭活效能及化学安全性研究
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摘要
针对建筑生活热水系统水力停留时间长、余氯含量低、微生物超标等问题,采用二次加氯方式进行二次消毒,研究二次加氯的消毒效能、余氯衰减及消毒副产物生成特性等。结果表明,二次加氯消毒可有效保障生活热水的生物安全性,投加0.2～0.5 mg/L次氯酸钠均可完全灭活细菌总数和总大肠菌群,投加0.3～0.5 mg/L次氯酸钠在24～48 h内持续消毒效果良好。生活热水的余氯衰减速率和三氯甲烷生成量明显高于二次供水,存在消毒副产物超标的风险;随着水温和有机物含量的升高,余氯衰减速率、三氯甲烷生成速率和生成量均明显提高。综合考虑生活热水的生物和化学安全性、水力停留时间和持续消毒作用等方面的要求,0.3 mg/L次氯酸钠为二次加氯消毒的最适宜投加量。研究结果为生活热水系统二次加氯消毒技术的应用和水质安全保障提供了技术支持。
Aiming at the problems such as long hydraulic retention time, low residual chlorine content and too many microorganisms in domestic hot water system, the secondary disinfection was carried out by the method of booster chlorination. The disinfection efficiency of booster chlorination, decay of residual chlorine and generation of disinfection by-products were studied. The results showed that the booster chlorination had an excellent protection effect on the biological safety of domestic hot water. The total number of bacteria and Escherichia coli could be completely inactivated by adding 0.2～0.5 mg/L sodium hypochlorite and the addition of 0.3～0.5 mg/L sodium hypochlorite could maintain great disinfection effect in 24～48 h hydraulic retention time. The decay rate of residual chlorine and the content of trichloromethane in domestic hot water were significantly higher than those of secondary water supply, which resulting in greater risk of chemical safety. With the increase of water temperature and organic matter content, the decay rate of residual chlorine, the content and production rate of trichloromethane increased obviously. Taking into account the biological and chemical safety, hydraulic retention time and disinfection duration of domestic hot water. It is considered that 0.3 mg/L sodium hypochlorite is the most suitable dosage for booster chlorination. The results provide technical support for the application of booster chlorination disinfection technology and the safety protection of water quality in the domestic hot water system.
Aiming at the problems such as long hydraulic retention time, low residual chlorine content and too many microorganisms in domestic hot water system, the secondary disinfection was carried out by the method of booster chlorination. The disinfection efficiency of booster chlorination, decay of residual chlorine and generation of disinfection by-products were studied. The results showed that the booster chlorination had an excellent protection effect on the biological safety of domestic hot water. The total number of bacteria and Escherichia coli could be completely inactivated by adding 0.2～0.5 mg/L sodium hypochlorite and the addition of 0.3～0.5 mg/L sodium hypochlorite could maintain great disinfection effect in 24～48 h hydraulic retention time. The decay rate of residual chlorine and the content of trichloromethane in domestic hot water were significantly higher than those of secondary water supply, which resulting in greater risk of chemical safety. With the increase of water temperature and organic matter content, the decay rate of residual chlorine, the content and production rate of trichloromethane increased obviously. Taking into account the biological and chemical safety, hydraulic retention time and disinfection duration of domestic hot water. It is considered that 0.3 mg/L sodium hypochlorite is the most suitable dosage for booster chlorination. The results provide technical support for the application of booster chlorination disinfection technology and the safety protection of water quality in the domestic hot water system.
引文
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[2] 钱城, 赵锐, 刘玉敏. 2006～2010年北京市宾馆饭店生活热水中嗜肺军团菌污染现状研究[C]. 中国建筑学会建筑给水排水研究分会第二次会员大会暨学术交流会, 2010.
[3] 于世明, 金玲, 高一凡,等. 沈阳市生活饮用水细菌学指标检测分析[J]. 沈阳师范大学学报(自然科学版), 2010, 28(1):72-74.
[4] Bargellini A, Marchesi I, Righi E, et al. Parameters predictive of Legionella contamination in hot water systems: association with trace elements and heterotrophic plate counts[J]. Water Research, 2011, 45(6):2315-2321.
[5] Boppe I, Bédard E, Taillandier C, et al. Investigative approach to improve hot water system hydraulics through temperature monitoring to reduce building environmental quality hazard associated to Legionella[J]. Building & Environment, 2016, 108:230-239.
[6] Lund V, Ormerod K. The influence of disinfection processes on biofilm formation in water distribution systems[J]. Water Research, 1995, 29(4):1013-1021.
[7] 王占生, 刘文君. 我国给水深度处理应用状况与发展趋势[J]. 中国给水排水, 2005, 21(9):29-33.
[8] 何红霞, 蒋兴锦. 自来水中的余氯对再污染微生物灭活作用的研究[J]. 中国消毒学杂志, 1991,(2):84-89.
[9] 黄晓东, 王占生. 氯化反应条件对三氯甲烷生成量的影响[J]. 中国给水排水, 2002,18(6):14-17.
[10] 王林, 吴纯德, 张积洋,等. 次氯酸钠应用于南方地区二次供水安全消毒的研究[J]. 水处理技术, 2012, 38(11):107-111.
[11] 游浩荣. 典型南方地区供水管网二次消毒的试验研究及应用[D]. 哈尔滨:哈尔滨工业大学, 2015.
[12] 钟丹. 给水管网余氯衰减规律及影响因素研究[D]. 哈尔滨:哈尔滨工业大学, 2010.
[13] 张小璐, 杨宏伟, 王小亻毛,等. 消毒副产物生成的温度影响和动力学模型[J]. 环境科学, 2012, 33 (11):4046-4051.
[14] 黄赛琴. 天津市供水管网余氯衰减规律的研究[D]. 哈尔滨:哈尔滨工业大学, 2005.