• Journal of Korean Society of Water and Wastewater
• /
• v.14 no.1
• /
• pp.108-116
• /
• 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 Soil and Groundwater Environment
• /
• v.18 no.1
• /
• pp.16-25
• /
• 2013

The Korean groundwater law regulates 20 groundwater contamination parameters, including 14 specific harmful substances. Expanding the number of groundwater quality standards are needed to cope with recent groundwater quality deterioration due to the use of various chemicals. Chemical ranking and scoring system (CRS) is a scientific tool to sort priority chemicals by considering exposure and toxicity potentials. In this study, we developed a CRS for scoring and ranking of possible groundwater pollutants and screened priority substances to be later considered in the Korean standard expansion. Chemical Ranking Of groundWater pollutaNts (CROWN) incorporates important parameters consisting of exposure potential, human and water ecotoxicity, interests, and certainty. Furthermore, CROWN additionally evaluated existence of other media standards to consider impacts by contamination of other media. The 197 substances that were common to 9 countries were selected first. CROWN evaluated and ranked each chemical, and finally suggested priority substances. Suggested priority substances were classified into two groups according to the groundwater use purposes: drinking and non-drinking. The priority substances were further classified into $1^{st}$ and $2^{nd}$ group priorities. The $1^{st}$ group consists of 75 substances, including the all the Korean groundwater standard parameters. CROWN will be used in selecting groundwater pollutants for possible inclusion in the Korean standard expansion.

• Hwankyungkyoyuk
• /
• v.3 no.1
• /
• pp.125-129
• /
• 1992

The purpose of this study was to investigate the condition of school water supply systems and to provide a way to supply safe and sanitary water in schools. In 1991 present, 56.9% of schools in the whole nation are provided with water supply system. And in urban schools, the percentage of small water supply system was larger than that in city. In the survey on water quality of supply water in Seoul city, the items violating the water quality standard were total bacteria, Zinc and Manganse. For supply the safe drinking water changing the old water mains and executing periodical water quality surveys are needed in addition regulations on school supply water and sanitation are also necessary to the drinking water management in schools.

• Journal of Korean Society of Water and Wastewater
• /
• v.14 no.3
• /
• pp.224-230
• /
• 2000

Membrane processes are capable of removing much materials from water. The removal or rejection characteristics of a membrane is usually depend upon the nominal pore size or MWCO(molecular weight cut off). A membrane with a smaller nominal pore size or MWCO should be capable of removing smaller contaminants from water. A series of experiments was performed to investigate the separation characteristics of membrane processes which consisted of microfiltration(MF) and nanofiltration(NF). To evaluate removal efficiencies of some pollutants such as the consumption of $KMnO_4$, THMFP, NH3-N, Fe, Mn, and pesticides, source water sampled from the Kum river was treated by the those membrane processes. Also, the results of experiments were compared with those of conventional water treatment processes. By two types of the membrane process, total removal efficiency of $KMnO_4$ consumed, THMEP, and $NH_3-N$ were 91.0%, 84.3%, and 85.5%, respectively and those processes were efficient in pesticides removal as well. Most of the effluents satisfied the Korean standard of drinking water quality continuously in the experimental periods. However, NF was needed for producing the safe drinking water in case of treating the raw water contaminated with Mn since removal efficiency of MF was not high enough. On the basis of the experimental results, it was suggested that NF could be applied to remove not only $NH_3-N$ but THMFP even without pre-chlorination.

• Journal of the Korean GEO-environmental Society
• /
• v.2 no.3
• /
• pp.37-45
• /
• 2001

The characteristics of drinking groundwater quality was analyzed by investigating observed data during 1995-1997 in Daejeon city. As the analysis of observed data, the 30.1% of them were over the drinking water quality standards in Daejeon city and the unfit ratios of each region were 36.4% at Dong-Gu, 32.3% Daedeog-Gu, 31.2% Jung-Gu, 30.0% Seo-Gu and 25.2% at Yusoung-Gu. It was found that the items over the drinking water quality standards were 24 items and all of the mean concentration of water quality items were under the drinking water quality standard except Fe and Mn in 1997. The mean concentration of Fe was $1.31mg/{\ell}$ over the water quality at Daedeog-Gu and that of Mn was $0.53mg/{\ell}$ at Jung-Gu. The concentrations of $NH_3$-N, Mn, Fe, Al and F were increased rapidly in 1997, so that the cause of increasing also must be examined closely. It was found that the rainfall and unfit ratio(unfit frequency/test frequency) of E-coli and bacteria had the hydrologic persistance. The coefficient of correlation between them was 0.525. On the rainfall over 100mm, it was 0.673 and on the rainfall over 150mm, it was 0.641. The correlation between E-coli and rainfall was higher than that between bacteria and rainfall.

• Journal of Korean Society of Water and Wastewater
• /
• v.12 no.2
• /
• pp.83-89
• /
• 1998

The drinking water supply in Cheju entirely depends on the ground water and recently the polluted ground water bores are increasing. In 1993 Cheju Province Health-Environment Institute reported that the ground water quality of 26 of 98 bores under the drinking water quality standard. Therefore there are many investigation in the needs of the nitrate removal in the drinking water in the regin with no alternative water resources. In this study, the following results are obtained to remove the nitrate in biofilm filtration process in which uses ethanol as external carbon source. Over 90% of nitrate is removed after 10 days of experiment. The nitrate removal rate on filtration velocity is about 100% at 50m/day and 100m/day, and about 56% at 200m/day. The removal rate is reduced in 27% at 400m/day. Using ethanol as the external carbon source, denitrification kinetic is 1st-order. Denitrification constant k is 8.004($hr^{-1}$). The amount of the denitrificated-Nitrogen is increased as the contact time increased. Deoxydation rate constant ${\gamma}$ is 11.895($hr^{-1}$). 0.968g of ethanol(as TOC) is needed to remove 1g of nitrate and 0.291g is required to remove 1g of dissolved oxygen.

• Journal of Preventive Medicine and Public Health
• /
• v.10 no.1
• /
• pp.59-61
• /
• 1977

We are calling the erupting ground water as drugwater or mineral water in Korea and thinking those water is good for health from ancient. But most of them were used by mountainer as drinking water and food making water. Authors tried to investigate the evidence of contamination by user on the 10 erupting ground water and gained following results: 1. All of the mineral, waters on 10 area in Seoul were unfitable to drinking water standard. 2. In the view of the bacteriology 80% were contaminated by coliform group. 3. The highest value of the free carbon dioxide contents were 652.96 ppm at Sam Sun Mineral Water.

• Journal of Preventive Medicine and Public Health
• /
• v.22 no.4 s.28
• /
• pp.495-505
• /
• 1989

This study was conducted as a nationwide survey In Korea to determine the THM (trihalomethane) concentration levels in the drinking water of 14 selected cities. The survey was underdtaken in one city (Kwangju) during September and October of 1988 and 14 cities in January through February of 1989. The results were as follows : 1. The $KMnO_4$ consumption was 10.6mg/l-11.6mg/l in Pusan and Ulsan, exceeding the drinking water standard of 10mg/l. Pusan, Inchon, Kwangju, Ulsan, Mokpo and Junju areas also exceeded the ammonia nitrate standard of 0.5mg/l. Other tap waters surveyed were detected below the drinking water standards. 2. The THM concentrations of tap water measured in January and February of 1989 were detected in the range $1.20{\mu}g/l-150.8{\mu}g/l$. 3. In the comparative study of the THM concentration of tap water measured in the Kwangju area during September and October of 1998, the average THM concentation of $145.63{\pm}70.72{\mu}g/l$ showed a sixfold increase compared to that of $23.8{\pm}8.31{\mu}g/l$ surveyed in January and February 1989. 4. The proportion of the four THM compounds found in tap water was bromoform, 47% ; chloroform, 30% ; chlorodibromomethane, 13% ; and dichlorobromomethane, 10%. 5. Since the results indicate that the concentration of bromoform was 2-10 times higher than that of chloroform measured in the seaside district of Pusan, Ulsan and Cheju Island, it is reasonable to assume that the raw water was somehow Influenced by seawater. 6. The average lifetime cancer rate of the population exposed to chloroform measured in the surveyed areas was 17 cancer incidences per 1 million population. From the above results, the existence of THM in the distribution systems seems to be inevitable, since chlorine disinfection is performed in water treatment plants In our country. There seems to be a trend of increasing. THM cncentrations due to the contamination of raw water. In order to establish my form of regulations, health risk assessment is an imminent subject.

• Journal of Soil and Groundwater Environment
• /
• v.19 no.6
• /
• pp.24-29
• /
• 2014

To data, there was no systematic basis for establishing the content and allowed levels of general contamination substances in the Korean groundwater quality standards for non-drinking water. Recently, use of specific procedures for deriving valid groundwater quality standards have become mandatory. This study first investigated the methodology for deriving groundwater quality standards in the European Commission (EC), considering background groundwater quality and domestic and international standards related to water quality. Furthermore, this study investigated the existing specified procedure of standards related to water quality (e.g. surface water, drinking water, and wastewater). Our findings showed that EC and Member States presented the methods for deriving groundwater threshold values for general chemicals. Finally, we have proposed the following procedures of deriving Korean groundwater quality: (1) Selection of groundwater pollutant population, (2) selection and monitoring of priority substances, (3) monitoring, (4) selection of groundwater quality standard candidates, (5) selection of new substances and values for groundwater quality standards.

• Journal of Food Hygiene and Safety
• /
• v.17 no.2
• /
• pp.55-60
• /
• 2002

In order to investigate the microbiological contamination of spring water, we performed the standard plate count, coliform and psychrotrophilic bacteria in 109 spring waters in Seoul. Of 109 spring waters, geometirc mean standard plate count was 0.19 CFU/ml, and the highest in Mt. Boolam, 4..43 CFU/ml and Mt. Dobong, 3.86 CFU/ml, but not detected in Mt. Woomyun and Mt. Cheonggye. Four spring waters have shown over 100 CFU/ml in standard plate count. The geometric mean psychrotrophilic bacteria was 49.2 CFU/ml, the most prevalent spring water was Mt. Nam, 125 CFU/ml, the lowest Mt. Woomyeun. Among a total of 109, coliform was detected from 21 spring waters(19.3%) and the geometric mean of coliform was 0.005 MPN/100ml. The isolated genera of coliform were 7 isolates of E. coli(33%), 5 Klebsiella(24%), 4 Enterobacter(19%), 3 Citrobacter(14%) and 2 Serratia(10%), respectively. The 22 spring waters(20.2%) failed to meet the standard limits of drinking water based on regulation in Korea. The inappropriate rate of standard plate count in spring water was 4.5%, that of coliform was 81.1% and both of them was 13.6%. There was the significant correlation between standard plate count and psychrotrophilic bacteria in spring water(r=0.95, p<0.01).