• Journal of environmental and Sanitary engineering
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• v.9 no.2
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• pp.50-57
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• 1994

Densities of total and injured coliforms in treated water( TW ) and three tap water salt pies( Taps Kl, K2 and K3) of Ku- eui water treatment plant and one tap water sample( Tap T) of Tuk- do water treatment plant were measured 23 times from 1991 to 1992. Coliform regrowth in the water distribution system occurred three times during the study period. When the regrowth episode occurred, injured coliforms were always but total coliforms were not always detected in treated water. Mean densities of total coliforms in TW, and Taps Kl, K2, K3 and T were 0.8, 2.3, 1.9, 1.4 and 2.1 cfu/100mℓ by membrane filtration method using m- TF agar and those of injured coliforms were 3.4, 2.8, 2.5, 2.7 and 2.9 c1u/100mℓ using mondo- LES agar. The injury rates of TW and Taps Kl, K2, K3 and T were 89.5,77.4,67.9, 82.8 and 75.9%, respectively. The high injury rate of coliform bacteria in Seoul water supply can cause regrowth problems in distribution systems due to the repair of injured cells under an appropriate condition. It is recommended the injured coliforms should be measured in drinking water since they can lead to a significant underestimation of total coliforms and result in an inaccurate evaluation of the potential health risks.

• Journal of the Institute of Convergence Signal Processing
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• v.8 no.3
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• pp.211-216
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• 2007

The quality of tap water on the whole water-supply system, from a large filtration plant to a private faucet, has to be guaranteed the standards of drinking water. At this point in time, however, the supply process of the tap water has not been monitored and managed scientifically. The piped water, especially the most small-scale reservoirs(underground or overhead type) are always exposed to various contaminations and impurities. Recently monitoring systems of water-quality were spread on some large filtration plants or distributing reservoirs. In particular, the water quality monitoring method using the internet is adopted into some local government whose inhabitants can check up the water quality anytime and anywhere. The construction of this system that has to apply a large scale needs, and has a limitation on the small water-supply system, such as apartments, public facilities and small-scale underground or overhead reservoirs. In this work, we suggest the integration system of individual water-quality sensor modules that have a low price. By using the developed integration system and monitoring program operated on the internet, the system managers of reservoirs can monitor and manage water-quality characteristic values of drinking water in online. Since the proposed system was modularized, the system can be applied easily into various reservoirs with a low cost and regardless of its scale, small or large.

• Journal of the Institute of Convergence Signal Processing
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• v.10 no.3
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• pp.207-213
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• 2009

The quality of tap water on the whole water-supply system, from a large filtration plant to a private faucet, has to be guaranteed the standards of drinking water. At this point in time, however, the supply process of the tap water has not been monitored and managed scientifically. The piped water, especially the most small-scale reservoirs(underground or overhead type) are always exposed to various contaminations and impurities. Recently monitoring systems of water-quality were spread on some large filtration plants or distributing reservoirs. In particular, the water quality monitoring method using the internet is adopted into some local government whose inhabitants can check up the water quality anytime and anywhere. The construction of this system that has to apply a large scale needs, and has a limitation on the small water-supply system, such as apartments, public facilities and small-scale underground or overhead reservoirs. In this work, we suggest the integration system of individual water-quality sensor modules that have a low price. By using the developed integration system and online monitoring program operated on the internet, the system managers of reservoirs can monitor and manage water-quality characteristic values of drinking water in online. Since the proposed system was modularized, the system can be applied easily into various reservoirs with a low cost and regardless of its scale, small or large.

• Journal of Soil and Groundwater Environment
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• v.16 no.1
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• pp.12-18
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• 2011

To investigate the natural reduction characteristics of radon with a short half-life (3.82 day) in drinking Qgroundwater, we analyzed the changes of radon concentrations of groundwater, waters in storage tanks, and tap waters from the small-scale groundwater-supply systems (N = 301) by LSC (Liquid Scintillation Counter). We also analyzed the concentrations of uranium (half-life 4.5 billion years) in the waters by ICP/MS to compare with natural reduction of radon concentration. The radon concentrations of 68 groundwater-supply systems occupying 22.6% of the total samples exceeded the US EPA's Alternative Maximum Contaminant Level (AMCL : 4,000 pCi/L), with the average radon concentration of 7,316 pCi/L (groundwaters), 3,833 pCi/L (tank waters) and 3,407 pCi/L (tap waters). Compared to the radon levels of pumped groundwaters, those of tank and tap waters naturally reduced significantly down to about 50%. Especially, in case of 29 groundwater-supply systems with the groundwater radon concentrations of 4,000~6,000 pCi/L, average radon concentrations of the tank and tap waters naturally decreased down to the AMCL. Therefore this study implies that radon concentrations of drinking groundwater can be effectively reduced by sufficient storage and residence in tanks.

• Journal of environmental and Sanitary engineering
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• v.8 no.1
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• pp.67-80
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• 1993

This survey was carried out to take the status of seawater intrusion into groundwater wells located in the eastern area of Chejudo, to get the elementary data which may evaluate the level of would-be groundwater contamination, and to perform effective the effort that will supply the clear water for the residents. The sampling sites were northeastern districts of Haengwon, Handong, and Sangdo, southeastern districts of Susan, Nansan, and Samdal, and northwestern districts, as reference, of Aewol, Keumnung, Panpo, Kosan, Shindo, and Bosung. We collected the samples from the public tap water by month, and analysed electrical conductivity, sodium(Na), potassium(K), magnesium(Mg), calcium(Ca), bicarbonate($HC0_{3^-}$), and items of the criteria as drinking water. In the northeastern districts we also added the sampling sites to survey the fluctuations of dissolved solids according to distance from seashore, including two private boreholes and one public tap water of Dukchun. The result is as follows 1) In the northeastern district, the concentration of chloride ion showed large fluctations from 40mg/l to 100mg/l, but suitable for the criteria of drinking water. It was thought that the drought influenced. 2) In the Sangdo of the northeastern districts, similar tendancy to Hangwon and Handong was showed only in the concentration of chloride ion, but different tendancy was showed in chloride-bicarbonate ratio, calcium-magnesium ratio, and sodium adsorption ratio(SAR). Considering these facts, it was not thought that seawater intruded. 3) The components of Na and Cl showed rapid slope in the northeastern districts above 3km from seashore. 4) In the northwestern districts as reference, the concentration of chloride ion fluctuated slightly according to the sampling sites and dates, and the concentration of nitrate-nitrogen in some sites exceeded the criteria of drinking water. These were thought that the surface contaminants rather than the intrusion of seawater influenced mainly the groundwater, considering the correlation(r=0.732) of chloride ion and nitrate-nitrogen. 5) Then we must consider the regional characteristies of soil profile in order to prevent the contamination of groundwater, and moniter also the movement of main components within the sol1 profile, not only the research of the intrusion of seawater.

• Journal of Korean Society of Environmental Engineers
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• v.31 no.6
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• pp.460-466
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• 2009

The mixing method of water and chemicals is significant in a small-scale water supply system because drinking water should be supplied with a certain quantity of remaining chemicals maintained. In the present study, the concentration distribution and the mixing index were obtained from four models, which were to find out the optimal mixing method of water and chemicals. The two models brought the good mixing effects out of the four, one for providing chemicals from the center of water supply pipe and the other for setting up the semicircle block at the downstream of the chemicals-providing pipe. As a result, the mixing effect was found out to be increased due to the diffusion and the disturbance of flows. In conclusion, these numerical results are expected to contribute to designing the optimal mixing system.

• Membrane and Water Treatment
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• v.13 no.1
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• pp.39-49
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• 2022

Seawater desalination is doubtlessly a viable option to supply fresh drinking water. Nevertheless, RO (reverse osmosis) desalination plants in specific areas may be intermittently operated to match the imbalance between water demand and supply. Although a handful of works have been done on other membrane systems, few studies have attempted to mitigate fouling in intermittent RO systems. Accordingly, the objectives of this paper were to examine the effect of the intermittent operation on RO fouling; and to compare four intermittent operation modes including feed solution recirculation, membrane storage in the feed solution, deionized water (DI) recirculation, and membrane storage in DI water. Results showed that intermittent operation reduced RO fouling under several conditions. However, the extents of fouling mitigation were different depending on the feed conditions, foulant types, and membrane lay-up methods. When the feed solution was recirculated during the lay-up, the restoration of the flux was less significant than that by the feed solution feed-up. The use of deionized water during the lay-up was effective to restore flux, especially when the feed solution contains scale-forming salts (CaSO₄) and/or colloidal silica.

• Journal of Environmental Science International
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• v.21 no.9
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• pp.1031-1041
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• 2012

This study was carried out to investigate the characteristics of disinfection by-products (DBPs-trihalomethanes (THMs), haloacetic acids (HAAs) and haloacetonitriles (HANs) formation in chlorination of principal raw waters used for drinking water on Jeju Island, Korea. The domestic water supply of other area and humic acid solution (HA) were used as a reference point. The effects of chlorine contact time, solution temperature and pH on DBPs formation potential (DBPFP) were investigated for raw waters. In addition, the effect of $Br^-$ was studied for HA. The DBPFP (THMFP, HAAFP and HANFP) were increased with increasing chlorine contact time. Comparing the individual DBPFPs for raw waters, they decreased in the order of HAAFP > THMFP ${\geq}$ HANFP. As the solution temperature was increased, the THMFP, HAAFP and HANFP increased. With increasing the solution pH, the THMFP was increased, but HAAFP and HANFP were decreased. With the addition of 0.3 mg/L $Br^-$ for HA, the DBPFP was increased and the major chemical species changed: from trichloromethane to dibromochloromethane and tribromomethane for THMs; from dichloroacetic acid and trichloroacetic acid to tribromoacetic acid for HAAs; and from dichloroacetonitrile to dibromoacetonitrile for HANs.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2005.10a
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• pp.679-685
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• 2005

In Korea, water management policy had been successfully conducted until late 1980's. During the period, fundamental needs of human-being, such as requirements of drinking and irrigation waters and flood protection for living, had been satisfied. However, most of recent water problems occurred after the late 1980's such as water quality management and new water resources development, have been unresolved and accumulated. Because, our water governing institutions have become ineffective as water management issue has been changed gradually from fundamental human needs such as water supply and/or flood protection to complex/integrated issues, for example, river restoration. To solve those water problems accumulated, we needs a new paradigm of water governing institution such as setting up national water management committee and river basin committee, in order to coordinate water-related ministries' policies and establish national water resources planning in an integrated format.

• Journal of environmental and Sanitary engineering
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• v.17 no.1
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• pp.57-62
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• 2002

Carbon cast iron and Zinc coated steel were the most widely used portable water of supply and distribution Pipeline system. The leaching of red water in portable water could produce sericus environmental sanitary problems. Due to the red water was the most alternative to inner scale of metal pipeline. So this study was conducted the impact of red water on scale products, and was evaluated by the corrosive metal contaminants of 20 fears over. Surface tests, metal surface composition measurements of samples XRF, XRD, and SEM(EDS), analysis were used to investigate the corrosion characteristies of carbon cast iron and Zinc coated steel. As the contaminants of Fe increased the red water of carbon castiron pipe increased due to the scale products amount of $Fe_2O_3$ (Hemite).