生物膜對於建築供水系統中水質之影響

自來水淨水程序中使用加氯消毒已有一百餘年歷史,至目前為止仍是主要自來水消毒方式之一。消毒後的自來水進入配水管網中配送,維持一定量的剩餘餘氯濃度,以抑制自來水中微生物之再生。足夠濃度的餘氯含量,是維持自來水配送過程中水質穩定之要素。但自來水由配水管線中進入建築供水系統中,卻因停留時間過長、環境溫度較高等等因素,造成水中餘氯濃度降低,無法保持水質穩定及安全。微生物在自來水中再生甚至於水塔邊緣與管線內壁形成生物膜,微生物的生長將帶來水質劣化。本研究探討台灣民眾使用普遍之儲水裝置—頂樓水塔,清洗水塔對於水質的實際影響。在實驗室架設反應槽以模擬現實中建築供水情況,也同時進行現地建築供水系統採樣。欲了解清除儲水裝置中的生物膜以及沉積物對於水中微生物再生以及消毒副產物生成的改善狀況,並且觀察隨著時間推移水質的變化情形,對於經過建築供水系統之自來水水質進行化學性以及生物性穩定性之分析。本研究中觀察到久未清洗的自來水儲水裝置,會造成流經之自來水餘氯濃度下降,提升之水中總異營菌數,三鹵甲烷也因此增加。藉由清潔儲水裝置,實驗結果表示餘氯消耗量減少,建築供水系統在儲水裝置清洗過後餘氯濃度提高,總異營菌數則隨之降低。現地採樣期間共六個月,半年內觀察到水塔中的自來水雖然餘氯濃度稍微下降,仍維持相當低之總異營菌數。

關鍵字

自來水；水塔；自由餘氯；生物膜；總異營菌數；消毒副產物

並列摘要

Using chlorine as disinfection in water purification procedure has been more than 100 years. Drinking water in the distribution network maintains a certain amount of residual chlorine concentration to prevent regrowth of microorganisms. The sufficient residual chlorine concentration, maintaining the drinking water quality stability during the distribution system. However, regrowth of microorganisms might happen during the water main pipe and premise plumbing. The longer residence time and higher ambient temperature in water main and premise pluming might lead to some water quality problems. At the rooftop water tower and the inner pipe wall, microbes regrow in bulk water and biofilm. Unfortunately, microbial regrowth would lead water quality deterioration, such as taste, odor and even pathogens. This study explores about rooftop water tower which is common to use in many houses in Taiwan, and observes the water quality impact of cleaning the rooftop water tower. In the laboratory, there is a benchtop reactor system to simulate the reality of the household water supply, and also take water samples in the current building water supply system. By analyzing the change in microbial and chemical stability of water quality over time, to observe the microbial re-growth and formation of disinfection by-products(DBPs) in drinking water that passes through the premise plumbing. In this study, such long-running the drinking water storage device (such as rooftop water tower) was observed, which resulted in the decrease the concentration of residual chlorine, increase the heterotrophic plate count (HPC), and increase Trihalomethanes in the tap water. With the result of cleaning the water storage device, the experimental results showed that the consumption of residual chlorine was reduced after the water storage device was cleaned. During the experimental period of six months, the tap water in the rooftop water tower was observed that although the residual chlorine concentration decreased slightly, and the total number of total bacteria was still low.

並列關鍵字

Tap water ； rooftop water tower ； free residual chlorine ； heterotrophic plate count(HPC) ； biofilm ； disinfection by-products(DBPs)

參考文獻

Al-Jasser, A. O. (2007). Chlorine decay in drinking-water transmission and distribu-tion systems: pipe service age effect. Water Res, 41(2), 387-396. doi:10.1016/j.watres.2006.08.032

Allen, M. J., Edberg, S. C., & Reasoner, D. J. (2004). Heterotrophic plate count bac-teria--what is their significance in drinking water? Int J Food Microbiol, 92(3), 265-274. doi:10.1016/j.ijfoodmicro.2003.08.017

Baribeau, H., Krasner, S. W., Chinn, R., & Singer, P. C. (2005). Impact of biomass on the stability of HAAs and THMs in a simulated distribution system. American Water Works Association, 97, Number 2, 69-81.

Bartram, J., Cotruvo, J., Exner, M., Fricker, C., & Glasmacher, A. (2004). Hetero-trophic plate count measurement in drinking water safety management: report of an Expert Meeting Geneva, 24-25 April 2002. Int J Food Microbiol, 92(3), 241-247. doi:10.1016/j.ijfoodmicro.2003.08.005

Brown, D., Bridgeman, J., & West, J. R. (2011a). Predicting chlorine decay and THM formation in water supply systems. Reviews in Environmental Science and Bio/Technology, 10(1), 79-99. doi:10.1007/s11157-011-9229-8

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生物膜對於建築供水系統中水質之影響

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