• 상하수도학회지
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• 제28권1호
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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.

• 상하수도학회지
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• 제19권3호
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• pp.301-311
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• 2005

The characteristics of disinfection by-products (DBPs) formation at 28 water treatment plants in Korea were investigated. Investigated species of DBPs were trihalomethanes (THMs), haloacetic acids (HAAs) and chloral hydrate (CH). The maximum concentration of THMs was $84.1{\mu}g/L$, minimum and the averages were $6.9{\mu}g/L$ and $27.8{\mu}g/L$, respectively; the maximum concentration of $HAA_5$ was $90.8{\mu}g/L$, minimum and the averages were $3.8{\mu}g/L$ and $26.7{\mu}g/L$, respectively; while the maximum concentration of CH was $29.5{\mu}g/L$, minimum and the averages were $0.5{\mu}g/L$ and $7.4{\mu}g/L$, respectively. On the other hand, DBPs levels during summer months, when the water temperature was near $25^{\circ}C$, were nearly twice as great as DBPs levels during the winter season. The ratio of $THMs/HAA_5$ was 1.07, and $HAA_5$ and THMs were the dominant species of DBPS in the Kum-Sumjin river and Nakdong river, respectivley.

• 한국환경과학회지
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• 제24권4호
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• pp.541-547
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• 2015

Formation of disinfection by-products (DBPs) including trihalomethans (THMs) and haloacetic acids (HAAs) from chlorination of six different species (Chlorella vulgaris, Scenedesmus sp., Anabaena cylindrical, Microcystis aeruginosa, Asterionella formosa and Aulacoseira sp.) of algal extracellular organic matter (EOM). The EOM characteristics evaluation of six algal species reaching at the stationary phase in the growth curve showed most of its SUVA254 showed below 1 and this means hydrophilic organic matter is much higher than hydrophobic organic matter. Chloroform formation potential (CFFP), dichloroacetic acid formation potential (DCAAFP) and trichloroacetic acid formation potential (TCAAFP) were mainly composed of THMFP and HAAFP in the EOM of various algal species. In the case of THMFP/DOC and HAAFP/DOC values, EOM of blue-green algae has appeared highest and EOM of green algae and diatom in order. THMFP/DOC was higher than HAAFP/DOC in EOM of blue-green algae. In comparison of formation potential by unit DOC composed of HAAFP in algal species EOM, DCAAFP/DOC was 1.5 times to 7.5 time higher than TCAAFP/DOC in the EOM of blue-green algae, while DCAAFP/DOC was found to be relatively high compared to TCAAFP/DOC in the EOM of green algae and diatom.

• 한국물환경학회지
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• 제21권6호
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• pp.676-681
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• 2005

This study was researched for disinfection by-products (DBPs) by preozonation, prechlorination and/or postchlorination. DBPs including trihalomethanes (THMs), haloacetic acids (HAAs), halonitriles, and aldehydes were analyzed by the treatment steps of prechlorination, preozonation, sedimentation, filtration, and postchlorination comparatively. THMs were detected as $52.20{\mu}g/L$ after prechlorination and decreased during sedimentation and filtration process. The HAAs and aldehydes increased more during preozonaiton than prechlorination. However, chlorinated DBPs and aldehydes increased more by postchlorination. Chlorinated DBPs formed by preozonation increased 26% more than the chlorination process. If aldehydes were included in the total DBPs, DBPs increased up to 39% by preozonation. Preozonation could increase the removal efficiency of organic carbon during the coagulation and sedimentation processes. Ozonation might produce aldehydes that are not permitted for drinking water regulations. Also, DBPs were produced by preozonation than by chlorination. These results would bring a need for alternative disinfection studies to decrease DBPs.

• 한국식품영양과학회지
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• 제30권5호
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• pp.969-977
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• 2001

본 연구는 초등학교 영양사 160명을 대상으로 HACCP시 시스템 적용을 위해 급식기구 재질별 소독실태 및 이에 영향을 미치는 요인에 대하여 분석, 평가하였다. 급식기구 소독방법으로 스템제품중 식판은 전기가스식 소독 작업대 및 기타 스텐제품은 화학소독(차아염소산나트륨)과 열탕소독을 주된 소독방법으로 사용하고 있었으나 야채절단기, 분쇄기 탈피기의 51.0%이상은 사용후 소독을 실시하지 않고 있는 것으로 파악되었다. 나무제품은 역시 화학소독 (차아염소나트륨)과 열탕소독을 사용하여 소독을 잘 실시하고 있었으나 플라스틱 제품에 있어 위생도마를 제외한 빨간 플라스틱 통바가지, 밥주걱의 30% 가량은 사용후 소독을 실시하지 않고 있는 것으로 나타났다. 소독시기에 있어 칼의 경우 수시로 소독을 실시하는 경우가 37.2%, 나무주걱의 경우는 30.9%로 이들 기구를 수시로 소독해야 한다는 인식이 부족한 것으로 파악되었다. 또한 플라스틱 제품의 경우 밥주걱을 제외한 대부분의 제품이 수시로 소독을 실시해야 하나 빨간플라스틱통의 53.5%, 바기지 45.9%, 위생도마의 45.8%만이 수시로 소독을 실시하고 있는 것으로 나타났다, 급식기구 소독횟수에 있어 대부분의 급식기구가 매일 소독을 실시하고 있었으나, 반찬통, 야채절단기, 탈피기, 분쇄기, 나무주것은 다른 기구에 비해 낮게 나타나 이들 기구류에 대한 위생적 취급이 요구되어졌다. 초등학교 급식소에서 사용되고 있는 소곧방법은 영양사, 나이, 경력, 및 급식학생수, 급식실시기간, 배식형태에 의해서 영향을 받고 있었으며 특히 소독을 실시하지 않은 비율에 잇어서 영양사 나이 30대와 근무경력 6~10년 미만에서 가장 높게 나타났다. 또한 급식실시기간 6년이상과 교실과 식당을 병행하는 배식형태에서도 소독이 잘 실시되지 않고 있는 것으로 파악되었다. 급식기구 소독시기도 영양사 나이와 학력, 배식형태에의해 영향을 받고 잇었으며 소독횟수는 조리종사원수, 급식학생수, 급식실시기간에 의해서 영향을 받고 있는 것으로 나타났다. 따라서 본 연구를 토대로 추후 스텐재질의 야채절단기, 탈피기, 분쇄기 및 나무주걱과 플라스틱 제품의 소독방법에 대한 미생물적 연구가 행해져야 할것이며, 아울러 급식소 소독실태에 많은 영향을 미치고 있는 영양사들에 대해서는 지속적인 위생교육이 수반되어져야 할 것이다.

• 치위생과학회지
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• 제22권1호
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• pp.51-56
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• 2022

Background: The coronavirus disease (COVID-19) pandemic increased awareness regarding the importance of hand hygiene in infection prevention. Although social distancing and vaccination are the strongest ways to prevent infection, personal hand hygiene is the most basic and easiest way to maintain public health. However, in addition to hand washing using running water, sanitizing tissues, and disinfection products are convenient for hand hygiene, especially outdoors. Therefore, it is necessary to improve the appropriateness of individual hand hygiene methods. In this study, we investigated the degree of hand hygiene offered by various hygiene products and hand drying methods for maintaining hand hygiene. Methods: An LED UV light kit was used for fluorescent observation of hand contamination. Bacteria from the hands were cultured to compare the degree of hand hygiene offered by various hygiene products. Bacteria were cultured in a hand-shaped medium dish to identify areas vulnerable to hand hygiene. Moreover, the degree of hand hygiene was observed according to the drying method using bacterial cultures. Results: We confirmed that hand washing under running water with antibacterial soap, sanitizing with alcohol gel disinfectant, and wiping with antibacterial wet wipes was effective for hand hygiene compared to washing under running water alone. However, for all hygiene products, a large number of bacteria were detected on the fingertips. We verified that natural drying, rather than rubbing, is effective in maintaining hand hygiene. Conclusion: These results suggest that hand hygiene products and drying methods are critical in hand hygiene management. Therefore, these results provide a basis for determining whether an individual's hand hygiene management method is appropriate.

• 한국환경보건학회지
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• 제48권3호
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• pp.167-175
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• 2022

Background: Disinfection is essential to provide drinking water from a water source. The disinfection process mainly consists of the use of chlorine and ozone, but when chlorine is used as a disinfectant, the problem of disinfection by-products arises. In order to resolve the issue of disinfection by-products, electro-chlorination technology that produces chlorine-based disinfectants from salt water through electrochemical principles should be applied. Objectives: This study surveys the possibility of optimally producing active chlorine from synthetic NaCl solutions using an electro-chlorination system through RSM. Methods: Response surface methodology (RSM) has been used for modeling and optimizing a variety of water and wastewater treatment processes. This study surveys the possibility of optimally producing active chlorine from synthetic saline solutions using electrolysis through RSM. Various operating parameters, such as distance of electrodes, sodium chloride concentration, electrical potential, and electrolysis time were evaluated. Results: Various operating parameters, such as distance of electrodes, sodium chloride concentration, electrical potential, and electrolysis time were evaluated. A central composite design (CCD) was applied to determine the optimal experimental factors for chlorine production. Conclusions: The concentration of the synthetic NaCl solution and the distance between electrodes had the greatest influence on the generation of hypochlorite disinfectant. The closer the distance between the electrodes and the higher the concentration of the synthetic NaCl solution, the more hypochlorous acid disinfectant was produced.

• Environmental Sciences Bulletin of The Korean Environmental Sciences Society
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• 제10권S_3호
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• pp.127-137
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• 2001

The sonochemical Process has been applied as a treatment method and was investigated its effect on the decomposition of humic substances(HS). The reaction kinetics and mechanisms in the Process of sonochemical treatment for humic substances(HS) in wastewater have also been discussed. It was observed that the metal ions such as Fe(II) and Mn(II) showed catalytic effects, while Al(III), Ca(II), and Mg(II) had inhibitory effects on the decomposition of humic substances in sonochemical reaction with hydrogen peroxide. Experimental results also showed factors such as hydrogen peroxide dose affected the formation of disinfection by-products. Two trihalomethanes, chloroform and dichlorobromomethane were formed as major disinfection by-products during chlorination. The mechanism of radical reaction is controlled by an oxidation process. The radicals are so reactive that most of them are consumed by HS radicals and hydroxyl radicals can be acted on organic solutes by hydroxyl addition, hydrogen abstraction, and electron transfer. The depolymerization and the radical reaction of HS radicals appear to occur simultaneously. The final steps of the reaction are the conversion of organic acids to carbon dioxide.

• 한국환경보건학회:학술대회논문집
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• 한국환경보건학회 2005년도 Proceedings of KSEH.Minamata Forum
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• pp.103-114
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• 2005

Chlorine disinfection has been used in drinking water supply to disinfect the water-borne microbial disease which may cause to serious human disease. As Chlorination is still the least costly, relatively easy to use, chlorination is the primary means to disinfect portable water supplies and control bacterial growth in the distribution system. However, chlorine also reacts with natural organic matter (NOM), which presents in nearly all water sources, and then produces disinfection by-product (DBps), which may have adverse health effects. Although the existent DBPs have been reported in drinking water supplies, it is not feasible to predict the levels of the various DBPs due to the complex chemistry reaction involved. The objectives of this study were to investigate seasonal variation of DBPs formation and difference of DBPs concentration in the plant to tap water. The average concentration of THMs was 20.04 ${\mu}g/{\ell}$, HAAs 8-15 ${\mu}g/{\ell}$, HANs 2-4.5 ${\mu}g/{\ell}$ respectively. Distant variation of DBPs formation is that THMs concentration increase by 17% at 2 km point from the plant and by 28% at 7 km and HAAs, HANs also increase each by 16%, 32%, at 2 km from the plant and 35%, 56%, at 7 km. DBPs increase in water supply pipe continually. The seasonal occurrence of DBPs is that in May and August DBPs concentration is very high then in March, in May DBPs concentration is highest. The temperature is main factor of DBPs formation, precursor also. Precursor which was accumulated for winter flowed into the raw water by flooding in spring and summer and produced DBPs. Therefore for the supply of secure drinking water, it is required to protect precursor of flowing into raw water and to add to BCAA and DBAA to drinking water standards.

• 상하수도학회지
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• 제26권5호
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• pp.685-692
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• 2012

UV technology is widely used in water and wastewater treatment. Many researches have been conducted on microbial disinfection and micro pollutant reduction with UV treatment. However, the study on NOM with UV has limited because low/medium pressure UV lamp is not sufficient to affect refractory organics such as NOM. Pulsed UV treatment using UV flash lamp can be operated in the pulsed mode with much greater peak intensity. The pulse duration is typically in microseconds, whereas the interval between pulses is in the order of milliseconds. The high intensity of pulsed UV would mineralize NOM itself as well as change the characteristics of NOM. Chlorine demand and DBPs formation is affected on the changed amounts and properties of NOM. The objective of this study is to investigate the effect on NOM, chlorine residual, and chlorinated DBPs formation with pulsed UV treatment.