The survey of nitrosamines occurrence at Nakdong river is conducted in this study. The nine nitrosamines were analyzed by GC/LRMS using solid phase extraction (SPE) with a coconut charcoal cartridge. According to the study results, six nitrosamine compounds (NDMA, NMEA, NDEA, NDPA, NDBA, and NDPHA) ...
The survey of nitrosamines occurrence at Nakdong river is conducted in this study. The nine nitrosamines were analyzed by GC/LRMS using solid phase extraction (SPE) with a coconut charcoal cartridge. According to the study results, six nitrosamine compounds (NDMA, NMEA, NDEA, NDPA, NDBA, and NDPHA) were detected as ND~33.8 ng/L, ND~17.7 ng/L, ND~151.6 ng/L, ND~455.4 ng/L, ND~330.1 ng/L and ND~161.0 ng/L respectively at the Nakdong river. Among these, NDEA and NDPA are the most important compounds in terms of the nitrosamine contamination of the Nakdong river. The detected concentration of NDEA exceeded the CDHCS (California Department of Health Care Services) response level of 100 ng/L at several sites. The detected concentration of NDPA approached the response level (500 ng/L) at a few sites. When all nitrosamine concentrations were summed up, the maximum concentration of 735.7 ng/L was detected at the Nakdong river. An equation describing a decrease in total nitrosamine concentration along downstream sampling sites was proposed in this study. The equation can be used to predict the downstream nitrosamine contamination at the Nakdong river. Among various water quality parameters, T-N showed a good correlation with total nitrosamine concentration.
Also this study was detected five nitrosamines(NDMA, NMEA, NDEA, NDPA and NDBA) in Sewage Treatment Plants(STPs). NDMA, NMEA, NDEA, NDPA and NDBA were obtained ND~821.4 ng/L, 22.5~55.4 ng/L, 53.2~588.5 ng/L, ND~56.6 ng/L and ND~527.9 ng/L in STPs, respectively. At the Dalseocheon STP, NDMA was obtained as 821.4 ng/L. In Drinking Water Treatment Plants(DWTP), NMEA and NDEA concentration were increased to as high as 38.8 ng/L after ozonation process. However nitrosamines were decreased subsequent biological activated carbon(BAC) treatment process. It was supposed that nitrosamines were formed by O3 oxidation and were removed by biodegradation of BAC.
Oxidation characteristics by O3 alone and advanced oxidation process(AOP) O3/H2O2 were investigated with concentration of nine nitrosamines of 20 μg/L in the raw water and the rapid sand fil-tered water. In the raw water, the results showed that the aver-age removal efficiencies were maximum 43% by O3(5.0 mg/L) alone with contact time of 2 minute for NDMA, NMEA and NDEA and maximum 48% by O3(10.0 mg/L) alone with contact time of 20 minute for NPYR, NDPA, NMOR, NPIP, NDBA and NDPHA. In the rapid sand filtered water, the results showed that the av-erage removal efficiencies were about 50% by O3(5.0 mg/L) alone with contact time of 2 minute for nine nitrosamines. The average removal efficiencies by AOP process were increased more than 30% by O3(10.0 mg/L)/H2O2(5.0 mg/L) with contact time of 2~20 minute than O3(10.0 mg/L) alone with contact time of 2 minute in the raw water and the rapid sand filtered water. On the other hand, Concentrations of nitrosamines after oxidation process were higher than initial concentration of nitrosamines when O3 doses of 0.5~1.0 mg/L were applied. Thefore O3 doses for removal of nine nitrosamines were needed higher than O3 doses of 0.5~1.0 mg/L.
Besides, this study accessed the adsorption characteristics of the nine nitrosamine species on coal-based granular activated ca-rbon (GAC). The breakthrough appeared first for NDMA and sequentially for NMOR, NPYR, NMEA, NDPA, NDEA, and NPIP. On the other hand, NDBA and NDPHA were not detected in the treated effluent for the operation period. The maximum ads-orption capacity (X/M) for the seven nitrosamine species with apparent breakthrough points ranged from 52.8 μg/g (for NDMA) to 5027.2 μg/g (for NPIP). Carbon usage rate (CUR) for NDMA was 1.07 g/day, 13.4 times higher than that for NPIP (0.08 g/day). The X/M values for the seven nitrosamine species were fitted well with a linear regression (r2=0.94) by their octanol-water par-titioning coefficient (Kow).
Finally, the results of this study are expected to be useful for water quality management in DWTP.
The survey of nitrosamines occurrence at Nakdong river is conducted in this study. The nine nitrosamines were analyzed by GC/LRMS using solid phase extraction (SPE) with a coconut charcoal cartridge. According to the study results, six nitrosamine compounds (NDMA, NMEA, NDEA, NDPA, NDBA, and NDPHA) were detected as ND~33.8 ng/L, ND~17.7 ng/L, ND~151.6 ng/L, ND~455.4 ng/L, ND~330.1 ng/L and ND~161.0 ng/L respectively at the Nakdong river. Among these, NDEA and NDPA are the most important compounds in terms of the nitrosamine contamination of the Nakdong river. The detected concentration of NDEA exceeded the CDHCS (California Department of Health Care Services) response level of 100 ng/L at several sites. The detected concentration of NDPA approached the response level (500 ng/L) at a few sites. When all nitrosamine concentrations were summed up, the maximum concentration of 735.7 ng/L was detected at the Nakdong river. An equation describing a decrease in total nitrosamine concentration along downstream sampling sites was proposed in this study. The equation can be used to predict the downstream nitrosamine contamination at the Nakdong river. Among various water quality parameters, T-N showed a good correlation with total nitrosamine concentration.
Also this study was detected five nitrosamines(NDMA, NMEA, NDEA, NDPA and NDBA) in Sewage Treatment Plants(STPs). NDMA, NMEA, NDEA, NDPA and NDBA were obtained ND~821.4 ng/L, 22.5~55.4 ng/L, 53.2~588.5 ng/L, ND~56.6 ng/L and ND~527.9 ng/L in STPs, respectively. At the Dalseocheon STP, NDMA was obtained as 821.4 ng/L. In Drinking Water Treatment Plants(DWTP), NMEA and NDEA concentration were increased to as high as 38.8 ng/L after ozonation process. However nitrosamines were decreased subsequent biological activated carbon(BAC) treatment process. It was supposed that nitrosamines were formed by O3 oxidation and were removed by biodegradation of BAC.
Oxidation characteristics by O3 alone and advanced oxidation process(AOP) O3/H2O2 were investigated with concentration of nine nitrosamines of 20 μg/L in the raw water and the rapid sand fil-tered water. In the raw water, the results showed that the aver-age removal efficiencies were maximum 43% by O3(5.0 mg/L) alone with contact time of 2 minute for NDMA, NMEA and NDEA and maximum 48% by O3(10.0 mg/L) alone with contact time of 20 minute for NPYR, NDPA, NMOR, NPIP, NDBA and NDPHA. In the rapid sand filtered water, the results showed that the av-erage removal efficiencies were about 50% by O3(5.0 mg/L) alone with contact time of 2 minute for nine nitrosamines. The average removal efficiencies by AOP process were increased more than 30% by O3(10.0 mg/L)/H2O2(5.0 mg/L) with contact time of 2~20 minute than O3(10.0 mg/L) alone with contact time of 2 minute in the raw water and the rapid sand filtered water. On the other hand, Concentrations of nitrosamines after oxidation process were higher than initial concentration of nitrosamines when O3 doses of 0.5~1.0 mg/L were applied. Thefore O3 doses for removal of nine nitrosamines were needed higher than O3 doses of 0.5~1.0 mg/L.
Besides, this study accessed the adsorption characteristics of the nine nitrosamine species on coal-based granular activated ca-rbon (GAC). The breakthrough appeared first for NDMA and sequentially for NMOR, NPYR, NMEA, NDPA, NDEA, and NPIP. On the other hand, NDBA and NDPHA were not detected in the treated effluent for the operation period. The maximum ads-orption capacity (X/M) for the seven nitrosamine species with apparent breakthrough points ranged from 52.8 μg/g (for NDMA) to 5027.2 μg/g (for NPIP). Carbon usage rate (CUR) for NDMA was 1.07 g/day, 13.4 times higher than that for NPIP (0.08 g/day). The X/M values for the seven nitrosamine species were fitted well with a linear regression (r2=0.94) by their octanol-water par-titioning coefficient (Kow).
Finally, the results of this study are expected to be useful for water quality management in DWTP.
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