• Journal of Environmental Science International
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• v.11 no.5
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• pp.411-418
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• 2002

The current study evaluated the disinfection efficiency of free chlorine and chloramine for microorganisms on various pipe materials, such as copper, galvanized steel, carbon steel, and stainless steel. In addition, the effect of internal pipe corrosion and corrosion inhibitors on the bactericidal efficiency was evaluated using a simulated loop. For disinfection with a phosphate corrosion inhibitor, chloramination was found to be more effective than chlorination due to its persistence. Free chlorine disinfection was optimized with a high phosphoric acid concentration, while chloramine disinfection was optimized with a high phosphoric acid or low polyphosphate concentration. In simulated copper and galvanized steel loop tests, chloramination with phosphoric acid was demonstrated to be more effective.

• Journal of Korean Society of Water and Wastewater
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• v.32 no.3
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• pp.279-289
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• 2018

N-nitrosodimethylamine (NDMA) is a class of disinfection byproducts and a frequently detected nitrosamine with carcinogenic potentials. This review summarizes NDMA precursors, their formation mechanisms in chloraminated water, and mitigation strategies. Understanding the formation mechanism and characteristics of precursors is essential for developing a mitigation strategy. Dimethylamine (DMA), the most widely studied NDMA precursor, has an NDMA molar yield up to 3%. In comparison, a subset of tertiary amines, e.g., pharmaceuticals, generate up to 90% upon chloramination. Potent NDMA precursors, are characterized by their negative partial charge, low planarity values and molecular weight, and high bond length and $pK_a$ values. A nucleophilic substitution of tertiary amine on chloramine is a key reason for the high NDMA yield from the most potent NDMA precursors. The distribution and fate of NDMA in surface water, aquifers, and its formation in the distribution system can be mitigated through two strategies: (1) degrading or/removing NDMA after its formation and (2) pre-treatment of its precursor's prior chloramination.

• Journal of Environmental Health Sciences
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• v.25 no.3
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• pp.77-82
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• 1999

This study was carried to investigate the characteristics of chloramination as a disinfection in drinking water distribution system. The raw water comes from midstream of Han river. In the range of pH 6~8, preformed chloramine of $Cl_2/NH_3-N$ ratio 5:1 had the HPC inactivation of more than 99% with lower pH and shorter contact time and available chloramine residual was decreased a little. In the chloramines of $Cl_2/NH_3-N$ ratio 3:1~5:1, the higher $Cl_2/NH_3-N$ ratio, the much inactivation of HPC was increased, but as contact time was longer, HPC inactivation of $Cl_2/NH_3-N$ ratio 3:1~5:1 were equaled. Bactericidal activity of three chlorine and postammoniation was influenced by free available chlorine completely and that of preammoniation was as follows : free chlorine ${\fallingdotseq}$ postammoniation>preammoniation>preformed chloramine.

• Journal of environmental and Sanitary engineering
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• v.14 no.1
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• pp.11-16
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• 1999

This study was performed to investigate THMs formation by chloramination as a secondary disinfection in drinking water distribution system. As the $Cl_2/NH_3-N$ ratio increased from 1:1 to 4:1, the THMs concentration had actually no change in the breakpoint curve of pH 6, 7. At pH 8, THMs level was not augmented at between 1:1 and 5:1. In the $Cl_2/NH_3-N$ ratio of more than 5:1 and 6:1 respectively, THMs level was raised. Only the chloroform of THMs was insignificantly detected by both preformed chloramine and preammoniation applications, which was probably attributed to the stoichiometrically unstable equilibrium in the preparation of chloramine, whereas $CHCl_3$, $CHCl_2Br$ and $CHClBr_2$ of THMs were found in the application of free chlorine. However it turned out that the THMs levels by chloramine was incomparably inferior to that of free chlorine.

• Journal of Environmental Science International
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• v.10 no.3
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• pp.247-252
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• 2001

This study was performed to evaluate the inactivation and microbial regrowth of heterotrophic and nitrifying bacteria using chloramine as a secondary disinfectant for drinding water distribution system. Three sets of the three reactors filled with the $Cl_2/NH_3-N$ ratio of 3:1, 4:1, and 5:1 were used in these experiments. Chloramine concentration were applied to each set of the reactors with $1mg/\ell$,\;2mg/\ell\;and\;3mg/\ell$, respectively. For the set with elapsed time and reached to zero level after 7 days. Heterotrophic bacteria remarkably increased and nitrification through the experimenatal period (21 day). Furthermore the regrowth of heterotrophic bacteria and nitrification were not found. More than $2mg/\ell$ of chloramine with $Cl_2/NH_3-N$ ratio of 3:1, the nitrification could be inhibited by 2 days of contact time.

• 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.

• Journal of Korean Society of Water and Wastewater
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• v.12 no.1
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• pp.45-51
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• 1998

The determinations of ammonia in water for drinking purpose served as one basis of judging the sanitary quality of water for a great many years. However, presently ammonia regulation varies depending on countries. In USA and Canada, ammonia is added to water for chloramination process. However, for korea, there is ammonia regulation of treated water in Korea which should not exceed 0.5mg/l as $NH_3-N$. There was a report exceeding 0.5mg/l of ammonia in chlorinated water when the famous drinking water contamination episode happened in the downstream of Nadong River, 1994. With lack of sewer distribution system and treatment plants of domestic wastes, many water treatment plants have a difficulty of complying with ammonia regulation in treated water. Breakpoint chlorination is usually performed to get rid of ammonia. The method which is allowed to measure ammonia in Korea is Phenate method. However, it would be undesirable to use Phenate method for measuring ammonia in chlorinated water if Phenate method would not differentiate ammonia from chloramine. A good possibility of interferences in measurement of ammonia exists because Phenate method include the step of the formation of chlorine and would not differentiate chloramine which is formed as a result of reaction between chlorine and ammonia. This study was on inaccuracy of Phenate method for measuring ammonia of chlorinated water when chloramine and ammonia coexist. This study found that Phenate method measured all chlormaine as ammonia. Ammonia measurement by ion chromatography confirmed this results. Finally, the result from this study suggests that ammonia measurement by Phenate method in chlorinated water should be revised accordingly.

• Journal of Korean Society of Environmental Engineers
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• v.36 no.8
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• pp.542-548
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• 2014

Effects of bromide ($Br^-$) and iodide ($I^-$) concentrations, chlorine ($Cl_2$) doses, pH, temperature, ammonia nitrogen concentrations, reaction times and water characteristics on formation of iodinated trihalomethanes (I-THMs) during oxidation of iodide containing water with chlorine were investigated in this study. Results showed that the yields of I-THMs increased with the high bromide and iodide level during chlorination. The elevated pH significantly increased the yields of I-THMs during chlorination. The formation of I-THMs was higher at $20^{\circ}C$ than $4^{\circ}C$, $10^{\circ}C$ and $30^{\circ}C$. In chloramination study, addition of ammonium chloride ($NH_4Cl$) markedly increased the formation of I-THMs. Among the water samples collected from seven water sources including wastewater treatment plant (WWTP) effluent water (EfOM water), prepared humic containing water (HA water) and algal organic matter (AOM) containing water (AOM water), EfOM water generated the highest yields of I-THMs ($12.31{\mu}g/mg$ DOC), followed by HA water ($4.96{\mu}g/mg$ DOC), while AOM water produced the lowest yields of I-THMs ($0.99{\mu}g/mg$ DOC). $SUVA_{254}$ values of EfOM water, HA water and AOM water were $1.38L/mg{\cdot}m$, $4.96L/mg{\cdot}m$ and $0.97L/mg{\cdot}m$, respectively. The I-THMs yields had a low correlation with $SUVA_{254}$ values ($r^2$ = 0.002).