The removal of ammonia of low concentration from driking water by clinoptilolite is studied with such factors as particle size and amount of clinoptilolite, inihal concentration of ammonia and sodium, pH in influent, ...The removal of ammonia of low concentration from driking water by clinoptilolite is studied with such factors as particle size and amount of clinoptilolite, inihal concentration of ammonia and sodium, pH in influent, attrition looses and regeneration. Langmuir and Freundrich ion exchange isotherms are used to represent experimental isotherm data and experimental results indicate that clinoptilolite is an attractive and promising agent for removal of ammonia of low concentration from drinking water, and the ion exchange process is suitable for Freundlich isotherm.展开更多
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 ...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 than67% 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.展开更多
文摘The removal of ammonia of low concentration from driking water by clinoptilolite is studied with such factors as particle size and amount of clinoptilolite, inihal concentration of ammonia and sodium, pH in influent, attrition looses and regeneration. Langmuir and Freundrich ion exchange isotherms are used to represent experimental isotherm data and experimental results indicate that clinoptilolite is an attractive and promising agent for removal of ammonia of low concentration from drinking water, and the ion exchange process is suitable for Freundlich isotherm.
基金supported by US EPA STAR program(No.83517301)Missouri Department of Natural Resourcesthe support from Chemistry Department,Environmental Research Center,and Center for Single Nanoparticle,Single Cell,and Single Molecule Monitoring(CS3M)at Missouri University of Science and Technology
文摘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 than67% 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.
