Mitch William A, Sedlak David L
Department of Civil and Environmental Engineering, 609 Davis Hall, University of California, Berkeley, Berkeley, California 94720, USA.
Environ Sci Technol. 2004 Mar 1;38(5):1445-54. doi: 10.1021/es035025n.
The potent carcinogen, N-nitrosodimethylamine (NDMA), is produced during disinfection of municipal wastewater effluent from the reaction of monochloramine and organic nitrogen-containing precursors. To delineate the sources and fate of NDMA precursors during municipal wastewater treatment, NDMA formation was measured after extended chloramination of both model precursors and samples from conventional and advanced wastewater treatment plants. Of the model precursors, only dimethylamine, tertiary amines with dimethylamine functional groups, and dimethylamides formed significant NDMA concentrations upon chloramination. In samples from municipal wastewater treatment plants, dissolved NDMA precursors always were present in primary and secondary effluents. Biological treatment effectively removed the known NDMA precursor dimethylamine, lowering its concentration to levels that could not produce significant quantities of NDMA upon chlorine disinfection. However, biological treatment was less effective at removing other dissolved NDMA precursors, even after extended biological treatment. Significant concentrations of particle-associated NDMA precursors only were detected in secondary effluent at treatment plants that recycled water from sludge thickening operations in which dimethylamine-based synthetic polymers were used. Effective strategies for the prevention of NDMA formation during wastewater chlorination include ammonia removal by nitrification to preclude chloramine formation during chlorine disinfection, elimination of dimethylamine-based polymers, and use of filtration and reverse osmosis to remove particle-associated precursors and dissolved precursors, respectively.
强效致癌物N-亚硝基二甲胺（NDMA）是在城市污水排放消毒过程中，由一氯胺与含氮有机前体反应生成的。为了确定城市污水处理过程中NDMA前体的来源和去向，对模型前体以及传统和先进污水处理厂的样品进行长时间氯胺化处理后，测定了NDMA的生成情况。在模型前体中，只有二甲胺、带有二甲胺官能团的叔胺和二甲基酰胺在氯胺化处理后会形成显著浓度的NDMA。在城市污水处理厂的样品中，溶解态的NDMA前体始终存在于一级和二级出水中。生物处理有效地去除了已知的NDMA前体二甲胺，将其浓度降低到氯消毒时不会产生大量NDMA的水平。然而，即使经过长时间的生物处理，生物处理在去除其他溶解态的NDMA前体方面效果较差。仅在使用基于二甲胺的合成聚合物进行污泥浓缩操作并将水回收利用的污水处理厂的二级出水中，检测到了显著浓度的与颗粒物相关的NDMA前体。在废水氯化过程中预防NDMA生成的有效策略包括通过硝化作用去除氨，以防止氯消毒过程中形成氯胺；消除基于二甲胺的聚合物；分别使用过滤和反渗透去除与颗粒物相关的前体和溶解态前体。
