• Journal of Korean Society on Water Environment
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• v.20 no.2
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• pp.145-150
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• 2004

This study investigated the effect of chlorine dose and chlorine reaction time for the formation of haloacetic acids (HAAs). According to the results, HAA formation was highly affected by chlorine dose and chlorine reaction time. HAA formation reached a plateau value at 30 mg/L of chlorine dose and 24 hr of chlorine reaction time. For the speciation of formed HAAs in the test water, the concentration of brominated-HAAs was significantly lower than that of chlorinated-HAAs because of low level of bromide ion concentration in the test water. It also investigated the removal efficiency of HAA precursors by several unit processes, such as ozone alone, UV alone, and combined ozone/UV system. Of them, ozone/UV system was proved as the best process to control the HAAs formation. The increase of the brominated-HAAs was observed during ozonation with and without UV irradiation showing the slight increase of total HAA concentrations.

• Journal of the Korean Society of Safety
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• v.33 no.5
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• pp.51-59
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• 2018

It is difficult to determine the outdoor toxic level of hazardous chemicals that are leaked in the building, since there are no efficient ways to calculate how much percentage of the leaked chemicals is released into the outdoor atmosphere. In address to these problems, we propose a reasonable box model that can quantitatively evaluate the mass rate of the indoor chlorine leakage into the outside of the building. The proposed method assumes that the indoor chlorine leakage is fully mixed with the indoor air, and then the mixture of the chlorine and indoor air is exfiltrated into the outside of the building through effective leakage areas of the building. It is found that the exfiltration rate of the mixture of the chlorine and indoor air is strongly dependent on the temperature difference between inside and outside the building than the atmospheric wind speed. As compared with a conventional method that uses a vague mitigation factor, our method is more effective to evaluate the outdoor toxic threat zone of the chlorine that are leaked in the building, because it can consider the degree of airtight of the building in the evaluation of the threat zone.

• Journal of Korean Society of Water and Wastewater
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• v.19 no.6
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• pp.713-719
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• 2005

SPME (Soild phase microextraction) has been used in the analysis of many volatile organic compounds, such as geosmin and 2-methylisoborneol (2-MIB), trihalomethanes (THMs) in drinking water. SPME fiber is characterized by high adsorption capacity (DVB/CAR/PDMS, DVB/PDMS etc.). Although the highly active adsorption capacities of the SPME fiber are often to the chemical functional group, surface properties play a significant role in determining the surface adsorption capacities. The objectives of this study were to evaluate effect of residual chlorine on analysis of geosmin and 2-MIB. Image taken by SEM before preloaded with chlorine, the surface and porous media was almost perfect spherical shape and no clogging of pores. However, after preloaded with chlorine the surface was aggregated and pore was blocked. The recovery rate of geosmin and 2-MIB coexisting with chlorine was reduced by 35 to 62%. The recovery rate with preloaded with chlorine was reduced by 25 to 43%. The lower concentration of geosmin and 2-MIB and the higher concentration of chlorine existed in water, the lower the recovery rate was.

• Journal of Korean Society of Water and Wastewater
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• v.14 no.1
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• pp.108-116
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• 2000

Chlorine is widely used as a disinfectant in drinking-water systems throughout the world. Chlorine residual was used as an indicator for prediction of water quality in water distribution systems. The variation of chlorine residual in drinking water distribution systems of Suwon city was simulated using EPANET. EPANET is a computerized simulation model which predicts the dynamic hydraulic and water quality behavior within a water distribution system operating over an extended time period. Sampling and analysis were performed to calibrated the computer model in 1999 (Aug. Summer). Water quality variables used in simulations are temperature, roughness coefficient, pipe diameter, pipe length, water demand, velocity and so on. Extended water residence time affected water quality due to the extended reaction time in some areas. All area showed the higher concentration of chlorine residual than 0.2mg/l(standard). So it can be concluded that any area in Suwon city is not in biological regrowth problem. Rechlorination turned out to be an useful method for uniform concentration of free chlorine residual in distribution system. The cost of disinfectant could be saved remarkably by cutting down the initial chlorine concentration to the level which guarantees minimum concentration (0.2mg/l) throughout the distribution system.

• Journal of Korean Society of Water and Wastewater
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• v.28 no.1
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• pp.61-72
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• 2014

Study on effluent organic matter (EfOM) characteristic and removal efficiency is required, because EfOM is important in regard to the stability of effluents reuse, quality issues of artificial recharge and water conservation of aqueous system. UV technology is widely used in wastewater treatment. Many reports have been conducted on microbial disinfection and micro pollutant reduction with UV treatment. However, the study on EfOM with UV has limited because low/medium pressure UV lamp is not sufficient to affect refractory organics. The high intensity of pulsed UV would mineralize EfOM itself as well as change the characteristics of EfOM. Chlorine demand and DBPs formation is affected on the changed amounts and properties of EfOM. The objective of this study is to investigate the effect on EfOM, chlorine residual, and chlorinated DBPs formation with low pressure and pulsed UV treatment. The removal of organic matter through low pressure UV treatment is insignificant effect. Pulsed UV treatment effectively removes/transforms EfOM. As a result, the chlorine consumption is changed and chlorine DBPs formation is decreased. However, excessive UV treatment caused problems of increasing chlorine consumption and generating unknown by-products.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.32 no.3
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• pp.65-74
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• 2000

This study was carried out to acquire basic data necessary for the use of rice-straw chemical pulp. It investigated the proper bleaching conditions when rice-straw chemical pulps(alkaline sulfite-Na2S2O4 pulp) were bleached with the various kinds of bleaching agents. And physical properties of bleached pulps were tested. The results of this study were as follows; 1, The proper conditions of chlorine sequence were determined to be 4% concentration of chlorine 25$^{\circ}C$ of reaction temperature and 50 minutes of reaction time. 2. For calcium hypochlorite sequence the proper conditions of chemical concentration reac-tion temperature and reaction time were 3% 25$^{\circ}C$ and 20 minutes respectively. 3. For chlorine dioxide sequence the proper conditions were 1% concentration of chlorine dioxide 70$^{\circ}C$ of reaction temperature and 2hr. of reaction time. 4. The proper conditions of hydrogen peroxide sequence were 1.5% concentration of hydro-gen peroxide 70$^{\circ}C$ of reaction temperature and 1hr. of reaction time respectively. 5. When the rice-straw chemical pulp were bleached with four kinds of bleaching agents methioned above in the proper conditions respectively brightnesses were the order of chlorine dioxide calcium hypochlorite, chlorine, hydrogen peroxide. And strengthes of pulps bleached with chlorine dioxide and hydrogen peroxide were higher than those of pulps bleached with other bleaching agents.

• Journal of the Korean Institute of Gas
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• v.8 no.2 s.23
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• pp.8-14
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• 2004

This study analyzed dispersion characteristics and toxic effect in the small-scale continuous release of chlorine gas. We found that the Gaussian model using the Briggs' dispersion coefficient and the effective release height was better predicting experiments than the BM model. From chlorine concentrations calculated by Gaussian model, simulation results showed that the dispersion of chlorine was more affected by atmospheric stability and wind speed than release rate and that the toxic effect of chlorine gas was similar to the effect of parameters on chlorine dispersion. From effected areas with toxic criteria, damaged areas could be estimated to protect human.

• Journal of The Korean Society of Clinical Toxicology
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• v.6 no.2
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• pp.99-103
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• 2008

Purpose: Chlorine gas is a common irritant that usually causes mild respiratory symptoms. One severe symptom, RADS (Reactive Airway Dysfunction Syndrome), is not well known to physicians. We analyzed the clinical features of chlorine gas exposure. Methods: We prospectively collected 25 cases of chlorine gas exposure near our emergency center on January 10th, 2007, and analyzed demographic data, event-to-ER interval, symptoms, and laboratory results based on medical records. Results: Only 2 patients out of 25 were admitted because of severe symptoms, the rest were discharged without complications. Sixty percent of them visited the ER within 12 h of exposure. The most common symptoms were chest discomfort (60%), headache (40%), nausea (40%), throat irritation (26%), and cough (32%). Two out of eight dyspnea cases showed abnormal pulmonary function, but only one case was diagnosed as RADS. Conclusion: Most symptoms after chlorine gas exposure can be treated conservatively. However, patients with chlorine exposure should be followed up long term for delayed complications.

• Journal of Korean Society of Disaster and Security
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• v.9 no.2
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• pp.63-75
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• 2016

For safe water supply, residual chlorine has to be maintained in tap-water above a certain level from drinking water treatment plants to the final tap-water end-point. However, according to the current literature, approximately 30-60% of residual chlorine is being lost during the whole water supply pathways. The losses of residual chlorine may have been attributed to the current tendency for water supply managers to reduce chlorine dosage in drinking water treatment plants, aqueous phase decomposition of residual chlorine in supply pipes, accelerated chlorine decomposition at a high temperature during summer, leakage or losses of residual chlorine from old water supply pipes, and disappearances of residual chlorine in water storage tanks. Because of these, it is difficult to rule out the possibility that residual chlorine concentrations become lower than a regulatory level. In addition, it is concerned that the regulatory satisfaction of residual chlorine in water storage tanks can not always be guaranteed by using the current design method in which only storage capacity and/or hydraulic retention time are simply used as design factors, without considering other physico-chemical processes involved in chlorine disappearances in water storage tank. To circumvent the limitations of the current design method, mathematical models for aqueous chlorine decomposition, sorption of chlorine into wall surface, and mass-transfer into air-phase via evaporation were selected from literature, and residual chlorine reduction behavior in water storage tanks was numerically simulated. The model simulation revealed that the major factors influencing residual chlorine disappearances in water storage tanks are the water quality (organic pollutant concentration) of tap-water entering into a storage tank, the hydraulic dispersion developed by inflow of tap-water into a water storage tank, and sorption capacity onto the wall of a water storage tank. The findings from his work provide useful information in developing novel design and technology for minimizing residual chlorine disappearances in water storage tanks.

• Journal of the Korean Society of Laryngology, Phoniatrics and Logopedics
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• v.14 no.2
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• pp.129-132
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• 2003

Chlorine gas is highly irritating gas that, when inhaled, can damage larger airways as well as distal lung structure. It occurs usually result in mild ocular, oropharyngeal, or respiratory symptom and recovery may proceed slow for several weeks. We reported four cases of dysphonia due to acute chlorine inhalation during a swimming pool accident were treated by voice therapy and medication.