Department of Chemistry and Environmental Research Center, Missouri University of Science and Technology, Rolla, MO 65409, USA; Center for Single Nanoparticle, Single Cell, and Single Molecule Monitoring (CS(3)M), Missouri University of Science and Technology, Rolla, MO 65409, USA.
Department of Chemistry and Environmental Research Center, Missouri University of Science and Technology, Rolla, MO 65409, USA; Center for Single Nanoparticle, Single Cell, and Single Molecule Monitoring (CS(3)M), Missouri University of Science and Technology, Rolla, MO 65409, USA.
J Environ Sci (China). 2018 Feb;64:82-91. doi: 10.1016/j.jes.2017.02.010. Epub 2017 Feb 24.
When adding sufficient chlorine to achieve breakpoint chlorination to source water containing high concentration of ammonia during drinking water treatment, high concentrations of disinfection by-products (DBPs) may form. If N-nitrosamine precursors are present, highly toxic N-nitrosamines, primarily N-nitrosodimethylamine (NDMA), may also form. Removing their precursors before disinfection should be a more effective way to minimize these DBPs formation. In this study, zeolites and activated carbon were examined for ammonia and N-nitrosamine precursor removal when incorporated into drinking water treatment processes. The test results indicate that Mordenite zeolite can remove ammonia and five of seven N-nitrosamine precursors efficiently by single step adsorption test. The practical applicability was evaluated by simulation of typical drinking water treatment processes using six-gang stirring system. The Mordenite zeolite was applied at the steps of lime softening, alum coagulation, and alum coagulation with powdered activated carbon (PAC) sorption. While the lime softening process resulted in poor zeolite performance, alum coagulation did not impact ammonia and N-nitrosamine precursor removal. During alum coagulation, more than 67% ammonia and 70%-100% N-nitrosamine precursors were removed by Mordenite zeolite (except 3-(dimethylaminomethyl)indole (DMAI) and 4-dimethylaminoantipyrine (DMAP)). PAC effectively removed DMAI and DMAP when added during alum coagulation. A combination of the zeolite and PAC selected efficiently removed ammonia and all tested seven N-nitrosamine precursors (dimethylamine (DMA), ethylmethylamine (EMA), diethylamine (DEA), dipropylamine (DPA), trimethylamine (TMA), DMAP, and DMAI) during the alum coagulation process.
当在饮用水处理过程中向含有高浓度氨的水源添加足够的氯以实现断点氯化时，可能会形成高浓度的消毒副产物 (DBP)。如果存在 N-亚硝胺前体，也可能形成剧毒的 N-亚硝胺，主要是 N-亚硝基二甲胺 (NDMA)。在消毒前去除其前体应该是一种更有效的方法，可以最大限度地减少这些 DBP 的形成。在这项研究中，沸石和活性炭被检查用于去除氨和 N-亚硝胺前体，当它们被纳入饮用水处理过程中。测试结果表明，丝光沸石可以通过单次吸附试验有效地去除氨和七种 N-亚硝胺前体中的五种。通过使用六桨搅拌系统模拟典型的饮用水处理工艺来评估实际适用性。丝光沸石应用于石灰软化、明矾混凝和粉末活性炭 (PAC) 吸附的明矾混凝步骤。虽然石灰软化过程导致沸石性能不佳，但明矾混凝不会影响氨和 N-亚硝胺前体的去除。在明矾混凝过程中，丝光沸石去除了超过 67%的氨和 70%-100%的 N-亚硝胺前体（除 3-(二甲氨基甲基)吲哚 (DMAI) 和 4-二甲氨基安替比林 (DMAP) 外）。当在明矾混凝过程中添加时，PAC 有效地去除了 DMAI 和 DMAP。选择的沸石和 PAC 的组合在明矾混凝过程中有效地去除了氨和所有测试的七种 N-亚硝胺前体（二甲胺 (DMA)、乙基亚甲基胺 (EMA)、二乙基亚胺 (DEA)、二丙基亚胺 (DPA)、三甲胺 (TMA)、DMAP 和 DMAI)。
