• Title/Summary/Keyword: 클로라민

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Formation of Organic Chloramines during Monochloramination of Natural Organic Matters (천연유기물과 모노클로라민의 반응시 유기성 클로라민 생성)

  • Lee, Wontae
    • Journal of Korean Society of Environmental Engineers
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    • v.36 no.9
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    • pp.604-608
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    • 2014
  • This study investigated influence of dissolved organic nitrogen (DON) in natural organic matter (NOM) on the formation of organic chloramines upon monochloramination. Ratios of dissolved organic carbon (DOC) to DON of the 16 NOM isolates ranged from 7 to 47 mg-C/mg-N. Levels of organic chloramines maxed in 24 hours at $0.16mg-Cl_2/mg-N$ in average. The yields were relatively lower, but decay of organic chloramines were slower than those upon chlorination. Organic chloramines formed upon monochloramination decreased by 56% in average in 120 h. NOM with lower DOC/DON ratios formed more organic chloramines. NOM fractions such as hydrophobic, hydrophilic, transphilic, and colloidal did not significantly impact formation of organic chloramines. As the monochloramine doses increased, more organic chloramines were produced ($R^2=0.91$). Overestimation of disinfection capacity due to the formation of organic chloramines may not be concerns for monochloramine systems since only 6% of monochloramine could be converted to organic chloramines upon monochloramination of NOM.

Influence of Dissolved Organic Nitrogen on Organic Chloramine Formation during Chlorination (염소 소독시 DON이 유기성 클로라민 생성에 미치는 영향)

  • Lee, Won-Tae
    • Journal of Korean Society of Environmental Engineers
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    • v.33 no.7
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    • pp.481-484
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    • 2011
  • Although formation of organic chloramines have been studied for decades, most of them have involved model organic compounds (e.g., amino acids) but not naturally occurring organic nitrogen in water. This study investigated formation of organic chloramines during chlorination of 16 natural organic matters (NOM) solutions which were isolated from surface water and contained dissolved organic nitrogen (DON). Organic chloramine yields per chlorine consumption was $0.25mg-Cl_2/mg-Cl_2$. Upon chlorination of NOM solutions, organic chloramines were rapidly formed within 10 minutes. The average organic chloramine yields upon addition of chlorine in to NOM solutions were $0.78mg-Cl_2/mg-DON$ at 10 minutes and $0.16mg-Cl_2/mg-DON$ at 24 hours. Organic chloramine yields increased as the dissolved organic carbon/dissolved organic nitrogen (DOC/DON) ratios decreased. Chlorination of molecular weight (10,000 Da) fractionated samples showed that the influence of DON molecular weights on the organic chloramine formation was minimal.

Prediction and Comparison for the N-Nitrosodimethylamine(NDMA) Formation (N-Nitrosodimethylamine(NDMA) 생성에 관한 예측과 비교 연구)

  • Kim, Jong-O;Kim, Dong-Soo
    • Journal of Korean Society of Environmental Engineers
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    • v.28 no.4
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    • pp.402-406
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    • 2006
  • N-Nitrosodimethylamine(NDMA) formation was studied as a function of chloramine concentration at a fixed dimethylamine (DMA) concentration of 0.05 mM at pH 7 and 8. Regression equations were developed by molar ratio of chloramine to DMA. The NDMA formation was dependent on molar ratio(chloramine/DMA) and was different when the ratio is less or greater than 1. The formation of NDMA increased with increasing chloramine concentration and a linear correlation was examined between NDMA concentration and the ratio on a log scale. The developed regression was applied to previously reported data and relative errors ranged from -79 to 163%. Regression equations could provide a potential tool to predict NDMA formation for a simple and quick estimation in water supply systems.

Comparison of Biofilm Removal Characteristics by Chlorine and Monochloramine in Simulated Drinking Water Distribution Pipe (모형 수도관에서 염소와 모노클로라민에 의한 생물막 제거 특성 비교)

  • Park, Se-Keun;Choi, Sung-Chan;Kim, Yeong-Kwan
    • Journal of Korean Society of Environmental Engineers
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    • v.28 no.1
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    • pp.26-33
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    • 2006
  • This study investigated the characteristics of the biofilm removal by free chlorine or monochloramine. The simulated drinking water distribution pipes on which biofilms had been formed were supplied with tap water containing 0.5, 1.0, 2.0 mg/L of free chlorine or monochloramine residuals. The biofilm removal was characterized by measurement of attached HPC and biomass on pipe surfaces. Chlorine was more effective in both inactivation of attached viable heterotrophic bacteria and removal of biofilm biomass compared to monochloramine. Biofilm matrix was not much eliminated from the surfaces by monochloramine disinfection. Free chlorine residual of 2.0 mg/L was found to be effective in biomass removal. However, biofilm level as low as $10CFU/cm^2$ of attached HPC and $5{\mu}g/cm^2$ of biomass still remained on the surfaces at 2.0 mg/L of chlorine residual. The measurement of biomass appeared to be a useful means in evaluating the characteristics of biofilm removal.

N-Nitrosodimethylamine(NDMA) Formation according to Various Factors (다양한 항목에 따른 N-Nitrosodimethylamine(NDMA) 생성에 관한 비교)

  • Kim, Jong-O
    • Journal of Korean Society of Environmental Engineers
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    • v.29 no.2
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    • pp.192-196
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    • 2007
  • In this study, a formation of N-nitrosodimethylamine(NDMA), a disinfection by-product, was investigated as a result of monochloramine addition in water. The NDMA formation was studied in terms of pH, dimethylamine(DMA), monochloramine concentration, and nitrogen composition in monochloramine. At a fixed DMA concentration of 0.01 mM or 0.05 mM, the NDMA formed concentration was quite different when the monochloramine to DMA ratio is less or greater than 1. The NDMA formation increased with increasing pH and a ratio of nitrogen composition in monochloramine to total nitrogen composition. At pH 7 and 8, more than five times higher NDMA formation was produced as a result of five times increase in DMA concentration. It was likely that monochloramine could be related to stimulate NDMA formation, if monochloramine may be produced with chlorine disinfection, in water treatment systems.

The characteristics of chloramine formation and decay with pH variation (pH 변화에 따른 클로라민 생성과 분해 특성)

  • 조관형;김평청;우달식;조영태
    • Journal of Environmental Science International
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    • v.11 no.4
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    • pp.347-353
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    • 2002
  • This study was conducted to investigate the characteristics of chloramination as a secondary disinfection in a drinking water distribution system. At the range from pH 6 to pH 8, monochloramine was predominant with a trace of dichloramine, and the free chlorine was detected after breakpoint. At $25^{\circ}C$, the breakpoints of pH 6, 7 and 8 appeared when the weight ratios of chlorine to ammonia nitrogen were 11:1, 9:1 and 10:1 respectively, and the peak points on the breakpoint curves at pH 6, 7 and 8 were in the Cl$_2$ / NH$_3$-N ratio of 9:1, 6:1 and 5:1 respectively. As pH increased from 6 to 8, maximum point of monochloramine on the breakpoint curve was moved from 7:1 to 5:1 in the weight ratio of chlorine to ammonia nitrogen. The maximum concentration of monochloramine was formed at the pH values of 7~8 and in the Cl$_2$ / NH$_3$-N ratio below 5:1. As the Cl$_2$/NH$_3$-N ratio increased and the pH lowered, chloramines decay proceeded at an increased rate, and residual chloramines lasted longer than the residual free chlorine. The monochloramine and the dichloramine were formed at pH 6, and then the dichloramine continued increasing with contact time.

Effect of Monochloramine and Dimethylamine Concentrations on the NDMA Formation (모노클로라민과 디메틸아민 농도가 NDMA 생성에 미치는 영향)

  • Kim, Jong-O
    • Journal of Korean Society of Environmental Engineers
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    • v.30 no.8
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    • pp.755-759
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    • 2008
  • As a disinfection byproduct, N-nitrosodimethylamine(NDMA) formation was studied according to chlorine, nitrogen, and carbon composition related to monochloramine and dimethylamine(DMA) concentrations. The highest NDMA formation was observed when the dimethylamine/monochloramine ratio was close to 1, and the formation was rapidly decreased when the ratio was less or greater than 1. The formation of NDMA increased with increasing chlorine/nitrogen ratio indicating the chlorine is a limiting factor. A rapid disinfection byproduct was formed at 72 hour contact time in this study. As the previous researches, pH was a significant factor for the NDMA formation.

A Study on N-Nitrosodimethylamine (NDMA) Formation According to pH Variation (pH 변화에 따른 N-Nitrosodimethylamine (NDMA) 생성에 대한 고찰)

  • Kim, Jong-O;Clevenger, Thomas
    • Journal of Korean Society of Environmental Engineers
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    • v.27 no.4
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    • pp.390-393
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    • 2005
  • N-nitrosodimethylamine (NDMA), a potent carcinogenic, has recently been observed at drinking water supply systems in USA and Canada. The NDMA formation was studied as a function of chloramine concentration (0.001-0.1 mM) at a fixed dimethylamine (DMA) concentration of 0.05 mM at different initial pH (6, 7, 8). It was found that the NDMA formation rate varied with pH values. The formation of NDMA increased with increasing chloramine concentration and showed maximum yields of 2.4% and 1.6% at pH 7 and 8, respectively. A good correlation ($r^2>0.99$) was observed between the molar ratio (chloramine/DMA) and NDMA formation at pH 7 and 8. Linearity of the NDMA formation appeared to be related to chloramine concentrations.

Combined Effects of Metal Coagulants and Monochloramine on Polyamide RO Membrane Performance (금속성 응집제와 모노클로라민의 상호작용이 Polyamide계 RO막 성능에 미치는 영향)

  • Kim, Kyunghwa;Hong, Seungkwan;Park, Chanhyuk;Yoon, Seongro;Hong, Seongpyuo;Lee, Jonghwa
    • Journal of Korean Society of Water and Wastewater
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    • v.20 no.4
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    • pp.637-643
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    • 2006
  • The bench-scale chlorine exposure study was performed to investigate the effect of pretreatment by free chlorine and monochloramine ($NH_2Cl$) on the performance of RO membranes made of polyamide (PA). Feed monochloramination at 2mg/L did not cause significant productivity loss compared to free chlorine. However, metal coagulants reacted with monochloramine, the PA membrane suffered from a gradual loss of membrane integrity by chlorine oxidation, which was characterized as a decrease in salt rejection. Especially, RO membranes exposed to alum coagulants with monochloramine revealed the salt rejection lower than those exposed to iron coagulants. XPS membrane surface analysis demonstrated that the chlorine uptake on the membrane surface increased and carbon peaks were shifted significantly when exposed to alum coagulants with monochloramine.

Efficiency of Different Disinfectants against Biofilm on Carbon Steel Pipe and Carbon Utilizing Ability of Biofilm (소독제에 따른 생물막 살균효율과 생물막 미생물집단의 탄소이용능 비교)

  • Lee, Dong-Geun;Lee, Jae-Hwa;Lee, Sang-Hyeon;Ha, Bae-Jin;Ha, Jong-Myung
    • Journal of Life Science
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    • v.16 no.4
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    • pp.579-583
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    • 2006
  • The influence of disinfectant on bacterial concentration and carbon usage patterns by Biolog GN plates were investigated for biofilm on carbon steel pipe. Heterotrophic bacterial concentrations were not different among non-, monochloramine- (1.0, 1.5 mg/l) and free chlorine- (0.5, 1.0 mg/l) treated samples (P = 0.56, ANOVA). However treatment of 1.5 mg/l free chlorine and 2.0 mg/l monochloraime showed significantly lower densities than control (P < 0.01, ANOVA). By the stepwise increasement of disinfectant concentration, the carbon usage activities of biofilm microflora were decreased after increase without the decrease of bacterial concentration, following reduction of cell density. Carbon usage patterns were qualitatively and quantitatively different with similar bacterial concentrations. Principal component analysis suggested that type and concentration of disinfectant were main factors on the usage of carbons. Our result suggest that the differences of bacterial communities were different among the samples and the need of monochloramine for the reduction of biofilm in drinking water.