• Journal of Korean Society of Water and Wastewater
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• v.28 no.6
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• pp.657-668
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• 2014

Under Korea's Enforcement Decree of the Framework Act on Environmental Policy amended in 2013, total organic carbon (TOC) is newly added as water quality parameter to assess organic pollution in water and aquatic ecosystem. To meet the TOC requirement and improve quality of effluent discharged into public watershed, it is also necessary to develop standards for TOC in effluent from public sewage treatment works (PSTWs). In this study, we reviewed the characteristics and removal efficiency of TOC in influent and effluent of PSTWs. The study found that phosphorus treatment process removed not only soluble phosphorus but also a portion of TOC remaining after the secondary treatment process. TOC concentration in effluent from PSTWs operated in tandem with industrial wastewater treatment work was higher due to influx of insoluble substances from the industrial wastewater treatment work. In order to lay a foundation for the management of TOC from PSTWs, it is necessary to carry out research on TOC from different perspectives. For example, studies on the generation mechanism of TOC and the impact of TOC on drinking water resources, assessment of effluent qualities through monitoring, and development of measures to control TOC for the preservation of aquatic ecosystem are needed.

• Journal of Environmental Health Sciences
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• v.44 no.3
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• pp.227-237
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• 2018

Objectives: This study was investigated the characteristics of small-scale water works (SWW) in Gyeongnam area and conduct a health risk assessment of water-quality inspection items unfitted for water-quality standards (WQS). Methods: The characteristics of SWW in Gyeongnam province were analyzed using the data of SWW in the last three years (2014~2016) published in National Waterworks Information System. In addition, the health risk assessment for inspection items unfitted for WQS was carried out in four steps: hazard identification, dose-response assessment, exposure assessment, and risk characterization. Results: The total number of SWW in Gyeongnam area was gradually decreased from 2014 to 2016. In addition, drinking water sources of SWW were in the order of ground water, valley water, spring water, surface water, and river-bed water. The number of points unfitted for WQS in SWW by year was 22, 45, and 18 in 2014, 2015, and 2016, respectively, and a total of 112 points were found to unfit for WQS in SWW during 2014~2016. The hazard quotient (HQ) for fluoride, nitrate nitrogen, boron in the unfitted points for WQS was more than 1.0, and the mean values for turbidity and color in points unfitted for WQS were 2.38 nephelometric turbidity unit and 16.25 color unit, respectively. Conclusions: The HQ for fluorine, nitrate nitrogen and boron was more than 1.0 in points unfitted for WQS among SWW in Gyeongnam area, and the turbidity and the color degree exceeded WQS, which mean that there is a possibility of harmful impacts on the human health.

• Journal of the Korean Society of Industry Convergence
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• v.24 no.5
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• pp.581-587
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• 2021

In recent years, contamination of drinking water sources has emerged as a serious social problem, such as a large number of impurities in tap water or groundwater or the supply of suitable water due to rust of pipes. Although the government and public institutions are implementing various measures to protect water sources, they cannot improve water quality in a short period of time because of the enormous cost involved. Therefore, in recent years, preference has been given to a device that converts tap water, which is hard water, into soft water by installing a separate water softener at the faucet from which tap water is discharged. However, the existing filtration device has a problem that filtration performance is gradually lowered when impurities accumulate in the filter, requiring continuous filter replacement. In this study, the optimal design of the filter housing was performed to develop a water softener that can be washed when impurities accumulate on the filter inside the water softener connected to the faucet. For optimal design of the filter housing, fluid and fluid-structural interaction analysis were performed on the design pressure to determine the shape and thickness of the housing, and design review was performed through prototype.

• Journal of Environmental Science International
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• v.1 no.1
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• pp.53-68
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• 1992

In order to research the adsorption removal characteristics of trace organic by-products in disinfection of drinking water by biological activated carbon(BAC), water samples disinfect- ted with $Cl_2$, $O_3$ and $ClO_2$ after treatment by fluidized-bed system with water added with humic acid(10mg/L) were investigated the formation and the removal of trihalomethanes (THMs), and the trace organic by-products by gas chromatography(GC) II gas chromatography/mass selective detector(GC/MSD). Control was used by activated carbon(AC) and water added with humic acid(HA). The results were summarized as follow : The THMs removal effect of BAC by chlorination was in lower 90 % than that of control(HA), the sorts of oxidants formed by $Cl_2$ , $O_3$ and $ClO_2$ were that $O_3$ was very fewer than $Cl_2$ or $ClO_2$, and that $ClO_2$ was fewer than $Cl_2$. The trace organic by-products were esters and phthalates etc. Based on results above, it is concluded that BAC was appeared the more desirable adsorbtion-degradation removal characteristics than that of AC.

• 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 Preventive Medicine and Public Health
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• v.39 no.1
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• pp.53-58
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• 2006

Objectives: We wanted to evaluate the main route of exposure to lead and cadmium for the general population in Korea by using multi-route and multi-media exposure assessment Methods: Samples of air at the homes, samples of the food and water and peripheral blood samples were collected from thirty volunteers living in Seoul (the metropolitan area), Yong-in (the suburban area) and Ansan (the industrial area) in 2001. Graphite furnace atomic absorption spectrometric methods were used for the determination of the Pb and Cd levels in the air, food, water and blood samples. Results: The average intake of lead through the air, drinking water and food were $5.06{\mu}g/day\;(26.3%)\;0.002{\mu}g/day\;(0.1%),\;and\;16.4{\mu}g/day\;(73.6%)$, respectively. The average intake of cadmium through the air, drinking water and food were $0.082{\mu}g/day\;(0.9%),\;0.001{\mu}g/day\;(0.007%),\;and\;12.61 {\mu}g/day\;(99.0%)$, respectively. The blood lead level was statistically higher in the male subjects than in the female subjects (3.39 and $2.22{\mu}g/dl$, respectively), and only gender was a significant variable on the multiple regression analysis for blood lead. Conclusions: This study showed that the intake of lead and cadmium through food was the major route of exposure. A policy to reduce the pollutants according to the exposure routes should be established. However, more studies will be needed to support these data for the general population.

• Journal of Preventive Medicine and Public Health
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• v.19 no.2 s.20
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• pp.273-280
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• 1986

'Medicinal water' have been used for the treatment of disease and the promotion of health. To study the quality and health effect of 'medicinal water', the eleven springs located near Taegu City during the period of March 27-February 17, 1986 were tested for biological and physiochemical examination and were checked for sanitary environment around the spring. Among them three springs (27.3%) had a good sanitary equipments and only one was negative for biological examination. Three 'medicinal warer' were accepted as potable by physicochemical examination. According to above findings, all of the 'medicinal water' sampled from the springs located near Taegu City were not potable by this sanitary survey adopted Drinking Water Standard in Korea. Kachang and Youngchum 'medicinal water' were more contaminated by heavy metals and bacteria than those of other springs. To solve the problem of contamination by heavy metals that originated from uncertain sources, we should search for the sources of water contamination, remove it completely and also support the environmental equipments and management system in protection of safe 'medicinal water' supply.

• Journal of Preventive Medicine and Public Health
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• v.26 no.2 s.42
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• pp.202-209
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• 1993

A accidental spills of phenol(100%) to the river Nakdong with subsequent contamination of the tap water fer about two million consumers in Taegu city of Korea were occurred in March 1991. A historical cohort study of 6,913 individuals was undertaken to determine the associated with illness. Population subjects were divided into two groups of exposed and unexposed. Exposed subjects were reported to be phenol associated symptoms significantly higher than those in a nearby unexposed area(39.6% vs 9.4%, p<0.01). Especially, in the related symptoms, highly significant differences were noted in the number of subjects reporting gastrointestinal illness such as nausea, vomiting, diarrhea, or abdominal pain. During the accident, study subjects who experienced peculiar taste or odor in the tap water were significantly higher in the exposed areas(92% vs 34.3%). Chlorophenols formed from chlorination of water may have aggravated the problem.

• Journal of Korean Society of Water and Wastewater
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• v.20 no.2
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• pp.215-223
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• 2006

The internal corrosion of water distribution systems is the main cause for the problem of the public health threat as well as water leakage in the damaged pipeline, red water, and odor and taste of the tap water. This study was examined the effect of chemicals used for pH and alkalinity control and corrosion inhibitors for producing the optimal corrosion control method. Corrosion study at different pH and alkalinity indicated that these control using alkaline chemicals was effective in corrosion rate, Fe release reduction, but examined to be increased in turbidity and corrosion-by-products(TTHMs) problems. The turbidity was slightly increased, requiring caution in controlling corrosion with $Ca(OH)_2$. At pH 9.0, TTHMs concentration is increased two times corn pared with non-control of pH. Using the pipe which had experienced 28 years of exposure, iron release was decreased with the corrosion inhibitor. Consequently, pH, Alkalinity control method using alkaline chemicals must be complemented by corrosion inhibitor application for efficient corrosion control.

• Journal of Preventive Medicine and Public Health
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• v.38 no.4
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• pp.457-464
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• 2005

Objectives : An outbreak of salmonellosis occurred among the student s and staff of D primary school in Yeongcheon-si, 2004. This investigation was carried out to prevent any recurrence of this outbreak and to study the infection source and transmission of the salmonellosis. Methods : The authors conducted a questionnaire survey among 1,205 students and staff members from D primary school about the ingestion of the school lunch and drinking water, and the manifestation of their symptoms. The author examined rectal swabs, the tap water and microorganism cultures, and we also investigated the dining facility and water supply facility. Results : The diarrheal cases were defined as the confirmed cases or the persons who had diarrhea more than one time with symptoms such as fever, vomiting and tenesmus. The diarrheal attack rate was 28.0%. Ingestion of fried bean curd with egg had a significantly high association with the diarrheal attack rate (p<0.05), and the relative risk of the fried bean curd with egg was 10.68 (95% CI=3.88-29.41), as was determined by logistic regression analysis. The bacterial counts in the tap water of the food preparation room and toilet (first floor) exceeded the maximum permissible counts. S. Enteritidis bacteria were only cultured from the fried bean curd with egg of all the supplied foods on September 3, 2004. Conclusions : The major cause of salmonellosis was presumed to be the contaminated bean curd via contaminated tap water due to a water leak of a school water pipe. This contaminated bean curd was under prepared, which allowed the S. Enteritidis to survive and multiply prior to its ingestion.