• Journal of Environmental Health Sciences
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• v.39 no.3
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• pp.223-229
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• 2013

Objectives: In an effort to examine the distribution of THMs (Trihalomethane) generated from chlorine disinfection by the drinking water treatment plants located on the east coast region of Gangwon-do, this study surveyed the distribution and concentrations of each component of THMs twice per month for 5 years from 2008 to 2012. Fluctuation pattern in the seasonal generation amount was identified. In addition, the correlation between the concentration of organic substances in water and THMs was assessed, along with stability of purified water quality supplied by the water treatment plants on the east coast by analyzing the composition ratio of each component that constitutes THMs and the detection frequency. Method: The research was done on purified water supplied by 29 water treatment plants in 7 cities and counties (Goseong-gun, Sokcho-si, Yangyang-gun, Gangneung-si, Donghae-si, Samcheok-si, Taebaek-si) located in Gangwon-do on the east coast. Water samples were collected twice a month from 2008 to 2012 and were investigate for chloroform, bromodichloromethane (BDCM), dibromochloromethane (DBCM), and bromoform, based on analysis through Purge-Trap (Tekmar 3000) devices using FID-attached GC (HP 6890, Hewlett Packard). Result: THMs concentration detected at Gangneung-si was 0.0086mg/L, Goseong-gun 0.0019mg/L, Donghae-si 0.0099 mg/L, Samcheok-si 0.0016 mg/L, Sokcho-si 0.0057 mg/L, Yangyang-gun 0.0027 mg/L and Taebaek-si 0.0038 mg/L. As the THMs composition rate, chloroform constitutes 51.4% followed bybromodichloromethane 22.3%, bromoform 15.2% and dibromochloromethane 11.1% respectively. Conclusion: Throughout the entire THMs survey areas and period, the maximum concentration was 0.072mg/L, which did not exceed the water quality standards (0.1 mg/L), and the overall average concentration was very low at 0.0044 mg/L.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.1
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• pp.115-119
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• 2005

As the regulations on DBPs are tightened, many water treatment plants (WTPs) in Korea have already introduced or will introduce enhanced coagulation, alternative disinfectants and advanced treatments such as ozonization and granular activated carbon to improve drinking water qualify. After a phenol leakage accident at the Nakdong-River in 1991, 26 WIPs in Korea introduced carbon dioxide generators, but there has been no accumulation of significant operating data. This research summarizes things that should be considered for the introduction of carbon dioxide disinfection process to WTPs based on one year operation data from A WTP that has had high concentration of DBP during a specific period in the summer. The removal efficiency of DBP was $30{\sim}40%$, but those of 2-MIB, Geosmin were less than 10%. The generation rate of $ClO_2$ by-products such as chlorite and chlorate were $70{\sim}100%$ of input dosage, but the ratios increased over time. At the same time, strong chlorine odors may be produced in the distribution system when $ClO_2$ was used with $Cl_2$ as a result of reaction between the chlorite and residual chlorine.

• YAKHAK HOEJI
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• v.21 no.4
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• pp.200-210
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• 1977

This investigation was undertaken from February 1976 to September 1976. The detergents in municipal sewages from the Chung Kae Stream, Ahn Yang Stream, and Bong Won Stream were determined at 1.5ppm, 0.93ppm, and 3.36ppm in average respectively. The concentrations of detergents determined in the Han river were 0.013ppm of Kwang Na Ru, 0.11ppm of Duk Do, 0.370ppm of Bo Kwang Dong, and 0.285ppm of Ka Yang Dong basin respectively. And the potable waters of Sung Book Ku and Sung Dong Ku from Ku Eu water pumping station located up-stream of the Han river were less polluted at 0.045ppm and 0.037ppm in average. Young Deung Po Ku and Su Dae Moon Ku had been relatively polluted at 0.181ppm and 0.133ppm. The coagulant, alum [$Al_{2}(SO_{4})_{3}$] could eliminated the small amount of detergent by coagulation. The eliminated rates were about 13% by 5ppm and 22.7% by 20ppm of aluminum sulfate in sewage contained 10ppm of turbidity. The sand and the charcoal adsorbed some detergent as the following Langmuir's equations: For the charcoal, m/x=0.029.$\times$1/Ce-11.43 For the charcoal, m/x=2.705log1/Ce-5.46 Where m: amount of snad and active carbon used(g) x: amount of detergent adsorbed from liquid(g) Ce:concentration in the liquid at equilibrium(miles) The adsorption effect of sand would be neglected. In the low concentration of detergent solution, one gram of active carbon adsorbed 0.263g of detergent. It was determined that one gram of chlorine reduced 5.5g pf DBS om keeping up 0.2ppm of residual chlorine by disinfection process with chlorine compound.

• Journal of Korean Society of Environmental Engineers
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• v.37 no.9
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• pp.511-516
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• 2015

On this study, we investigated the removal characteristics of residual chlorine and DBPs in tap-water during boiling. Also we investigated the releasing characteristics of essential minerals in infusion tea. While recent studies focused on removal mechanisms of harmful heavy metals in infusion tea, this study tried to suggest the way to drink tap-water healthier and safer by examining releasing mechanisms of essential minerals in infusion tea. As a result, residual chlorine(initial conc. was 0.7 mg/L) was all removed in 20 minutes after heating and DBPs (the sum of THMs, HAAs and CH) were removed up to 65%. 6 kinds of essential minerals (Ca, K, Na, Mg, S, P) were released from 5 kinds of infusion tea (barley tea, corn tea, brown rice tea, cassia seed tea, solomon's seal tea) on the market. In cassia seed tea, the amount of essential minerals released from tea showed the highest values, 9.6 mg/g, and brown rice tea was the lowest, 1.6 mg/g. Particularly, the released amounts of potassium, playing a key role in human body in maintaining normal blood pressure, cell metabolism and enzyme action, showed relatively high. Through this study, we got to know that essential minerals can be obtained up to 40% of recommended nutritional intake for Korean by boiling tap-water with infusion tea.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.10
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• pp.1035-1042
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• 2005

Granular Activated Carbon(GAC) is widely used in drinking water treatment. At S and B Water Treatment Plant, GAC is used in place of granular media in conventional rapid filters(GAC Filter-Adsorber) for removal of Disinfection By-products(DBPs). The primary focus of this study is on the performance of existing filter-adsorber, and their operation. It was found that F/A process removed turbidity as effective as sand system. The ratio of Hydrophobic DOM (HPO) and hydrophilic DOM (HPI) fraction in the raw water at S and B WTP was similar. Filter Adsorber presented earlier DOC breakthrough and steady state condition which was contributed by biodegradation during operation period. The removal efficiency of DBPs were used to evaluate the filter performance. The DBPs concentration of F/A treated water was below treatment goal level (THM < $80\;{\mu}g/L$, HAA < $60{\mu}g/L$). The removal efficiency of THM decreased rapidly during operation period. However, HAA were removed steadily regardless of the influent concentration of HAA. These results indicate that the removal of THM depend upon the adsorption mechanism while the removal of HAA depend upon biodegradation as well as adsorption. The decrease of adsorption capacity and characteristic value of GAC may be attributed to the effect of high organic loading, residual free chlorine, coagulants, manganese oxidants and frequently backwashing. This study has confirmed that Filter adsorber process can be considered as effective alternatives for the removal of DBPs, especially HAA.

• Journal of Environmental Impact Assessment
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• v.29 no.6
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• pp.403-413
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• 2020

A mathematical model comprised with eight simultaneous quasi-linear partial differential equations was suggested to provide optimal chlorination strategy. Upstream weighted finite element method was employed to construct multidimensional numerical code. The code was verified against measured concentrations in three type of reactors. Boundary conditions and reaction rate were calibrated for the sixteen cases of experimental results to regenerate the measured values. Eight reaction rate coefficients were estimated from the modeling result. The reaction rate coefficients were expressed in terms of pH and temperature. Automatic optimal algorithm was invented to estimate the reaction rate coefficients by minimizing the sum of squares of the numerical errors and combined with the model. In order to minimize the concentration of chlorine and pollutants at the final usage sites, a real-time predictive control system is imperative which can predict the water quality variables from the chlorine disinfection process at the water purification plant to the customer by means of a model and operate the disinfection process according to the influent water quality. This model can be used to build such a system in water treatment plants.

• Journal of Korean Society of Water and Wastewater
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• v.19 no.1
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• pp.78-91
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• 2005

Performance limiting factors (PLFs) derived from 161 drinking water treatment plants (DWTPs), assessed by International Technical Diagnosis & Assistance Center, were analyzed and evaluated in more detail in this study. In order to conduct study, 161 DWTPs were divided into five categories depending on their capacity, and into twelve groups according to processes and facilities. From the results of analysis, PLFs and their distribution ratio derived from each category were significantly different. Filtration was the most important performance limiting process in all DWTPs of five categories, and the PLFs in filtration were backwashing velocity, media configuration, bed depth, and formation of mud-ball. The PLFs in coagulation-flocculation process were found out to be coagulant dosage, mixing speed, mechanical problems, and others in the order of frequency of occurrence. Also, insufficient disinfection ability that is resulted from insufficient hydraulic detention time and improper chlorine dose and injection point, is the most significant among PLFs in a clear well. In the case of sedimentation, inappropriate baffle structure and excessive upward velocity were PLFs. In addition, the results showed that high turbid water and low alkalinity in a rainy season, ferric and manganese ions, and ammonia nitrogen have been contributed significantly on the performance of DWTPs.

• Textile Coloration and Finishing
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• v.18 no.6 s.91
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• pp.43-48
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• 2006

Electrolytic water(EW), studied in recent decades in the Japan, Russia and United State of America, have shown promise as a method of disinfection whereby low levels of free chlorine, sodium hypochlorite, or hypochlorous acid may be produced in situ in Nacl-containing solution. These methods have shown promise in destruction of microorganisms in medical, dental environment, and in the agriculture and food industry. A recently EW treatment system was evaluated for reducing scouring agent and other surfactants in the washing and scouring process of textile industry Unfortunately, there is, to my knowledge, no serious studies of the properties of EW for textile industry In order to study the characteristics of EW and confirm the possibility of applications in textile industry processes, the pH, surface activity, penetration force, surface tension, and contact angle of EW was measured under various conditions. In general terms, What all this shows is that there is fundamental difference between the properties of EW and that of distilled water.

• Journal of Korean Society of Environmental Engineers
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• v.30 no.7
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• pp.721-728
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• 2008

DBPs(Disinfection By-Products) are most formed through the reactions between chlorine and NOM(Natural Organic Matter) in water treatment. In this study, occurrence of DBPs including THMs(Trihalomethanes) is evaluated. Also, influencing factors by the seasons and raw water quality were investigated for correlation among them and the characteristics of THMs formation by prechlorination process. This study investigated the operation condition for THMs removal depending on raw water quality. Water treatment plant from intake station to gauging well flows for about 10 hours in Y Water Supply Office. It is limited to control of THMs formation because of excessive reaction time between chlorine and THMs precursors in the intake station. Therefore, as multi-points prechlorination from intake station to gauging well, THMs formation was decreased in the water treatment, and it was willing to prevent overdosage of chlorine. The concentration of THMs was 0.021 mg/L in the summer, 0.015 mg/L in the winter, respectively. Also, THMs formation showed that 0.013 mg/L in the water of gauging well after prechlorination, 0.014 mg/L in the flocculation/sedimentation/filtration, 0.016 mg/L in the water after postchlorination, respectively. THMFP(Trihalomethane Formation Potential) removed 42.7% and 50% through the flocculation/sedimentation and filtration, respectively, and it is similar TOC removal efficiency. In this study, multi-points prechlorination from intake station to gauging well decreases in contact time and concencrations of NOM and chlorine. Also, it decreases in THMs and amount of chlorine uesd. In the result of multi-points prechlorination in the summer, the concentration of THMs was 0.013mg/L in the treated water. In view of these facts, THMs formation can be decreased approximately 50%.

• Korean Chemical Engineering Research
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• v.44 no.2
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• pp.216-226
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• 2006

Total trihalomethanes (THMs), dichloroacetic acid (DCAA) and trichloroacetic acid (TCAA) that are the major disinfection byproducts (DBPs) are monitored continuously in drinking water in Seoul. Study on characteristics of DBPs is crucial to judge the safety of drinking water in Seoul. Analysis of THMs, haloacetonitriles (HANs), chloral hydrate (CH), and haloacetic acids (HAAs) was carried out in several distribution systems from January 2002 to December 2004. The concentration of THMs was 0.015 mg/L in purified water, 0.019 mg/L in tapwater by direct service, and 0.023 mg/L in tapwater through watertank, respectively. It might be due to the increased contact time with chlorine by a process of the distribution system. And the other DBPs show a tendency to increase in its concentration by a process of the distribution system. Also, in summer, the concentration of DBPs was higher than in spring and winter. It might be due to the higher temperature of water in summer. In all cases, the quantities of detected DBPs were 4-6 times lower than those of regulation limits of drinking water in Seoul. In view of these results, the tapwater in Seoul is good to drink it all the times.