飲用水配水系統消毒副產物及二氧化鉛溶鉛之健康風險評估

Health Risk Assessment of Disinfection By-Products and Pb In Drinking Water Distribution System

徐偉勵(Wei Li Hsu)

指導教授 ： 林逸彬

國立臺灣大學/工學院/環境工程學研究所/碩士(2014年)

https://doi.org/10.6342/NTU.2014.10170

摘要

自來水廠加氯消毒的目的是要確保飲用水的安全，加氯消毒過程所產生的消毒副產物，由流行病學及從動物實驗上證實為致癌物質，若以氯胺替代氯作為消毒劑，可降低消毒副產物的生成量，但因氯胺降解作用會導致鉛管中之二氧化鉛腐蝕產物產生還原性溶解，將鉛釋入水中，其所產生之風險也需加以考量。本研究針對加氯及氯胺在不同水質參數條件下，經由消毒副產物生成模式及二氧化鉛溶鉛模式，模擬在不同反應時間、消毒劑濃度、pH值、天然有機物濃度、溴離子濃度條件下生成之消毒副產物及溶鉛量，並計算其人體致癌風險及非致癌危害商數，結果顯示加氯消毒副產物導致的致癌風險值均大於氯胺加上溶鉛的風險值，非致癌性風險方面，加氯胺造成鉛溶出的危害商數皆大於1，顯示加氯胺雖可降低消毒副產物的生成，但若配水管線中有鉛管，溶出鉛的濃度可能會造成非致癌毒性危害。尤其若水中含有溴離子，消毒副產物生成量有倍增的情況，且溴離子會催化氯胺降解，導致鉛溶出量是未含溴離子的數倍，相對應之致癌及非致癌性的危害性也提高許多。自來水廠因消毒副產物生成過高，可考慮將消毒劑由加氯更換為氯胺，但必須評估可能造成之鉛釋出，及其所需之防腐蝕措施。

關鍵字

消毒副產物 ； 鉛 ； 氯 ； 氯胺 ； 風險評估

並列摘要

Chlorine is traditionally used to disinfect drinking water to prevent waterborne diseases but it can react with natural organic matter to form carcinogenic disinfection by products (DBPs). To reduce the formation of DBPs, chloramine has been used as an alternative disinfectant. Recent studies have reported that, however, chloramination may promote lead release from lead dioxide, a Pb(IV) corrosion product formed from the chlorination of lead pipe. Therefore, the reduced risk due to the suppression of DBPs formation and the increased risk associated with lead release need to be simultaneously considered when chloramine is used to replace chlorine for disinfection. This research investigates the formation of DBPs in chlorination/ chloramination and the possible lead release in chloramination in different scenarios to determine the overall carcinogenic and non-carcinogenic risks. Variables considered include reaction time, disinfectant concentration, pH value, total organic carbon concentration, and bromide concentration. It was found that carcinogenic risks resulting from DBPs formed from chlorination are generally higher than the combined carcinogenic risks resulting from DBPs formation and lead release when chloramine is used. The non-carcinogenic risks due to lead release, however, are much more important than those associated with DBPs. Particularly, when bromide is present, it promotes both DBPs formation and lead release and the risks are much higher than those in the absence of bromide. Chloramine can be used as an effective disinfectant to reduce DBPs formation. The non-carcinogenic risk due to lead release, however, needs to be evaluated and controlled to provide safe drinking water

並列關鍵字

Disinfection by-products ； Lead ； Chlorine ； Chloramine ； Risk assessment

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