• 한국환경과학회지
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• 제13권1호
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• pp.55-59
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• 2004

The effect of ozone on the formation and the removal of disinfection byproducts(DBPs) of chlorination process was studied to elucidate the performance of water treatment process. The samples of raw water, prechlorination process, and preozonation process were analyzed quantitatively according to the Standard Methods for the Examination of drinking water. As a result, most of total trihalomethanes(THMs) which were formed in prechlorine treatment process was not removed in the preozonation process. Most of haloacetic acids(HAAs), haloacetonitriles(HANs), and chloral hydrate(CH) was removed in sedimentation and biological activated carbon(BAC) filtration processes. However, DBPs were increased more or less by postchlorine step. In particular, the formation of THMs and HAAs depends on ozone more than chlorine, but, the formation of HANs and CH depends on chlorine more than ozone. The seasonal variation of DBPs concentration for the year needs to be investigated to study the temperature effect because DBPs strongly depend on temperature among various efficient factors.

• 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.

• Ecology and Resilient Infrastructure
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• 제5권3호
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• pp.111-117
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• 2018

선박평형수 처리에의 적용을 목적으로 다양한 미생물 농도, 소독제 주입량, pH 조건에서 이산화염소의 소독 효과를 조사하였다. 살균 반응 속도 및 소독 부산물 생성 여부는 선박평형수 처리에 일반적으로 사용되는 소독제인 염소와 비교 평가하였다. 선박평형수 배출 규제 항목인 E. coli 와 Enterococcus의 이산화염소에 의한 사멸 효과는 유사 2차 반응으로 모사하였다. 선박평형수 처리를 위한 최적 이산화염소 투입 농도는 1 mg/L으로 나타났다. pH 7.2 - 9.2 범위에서 이산화염소의 살균 반응 속도 상수의 변화폭이 5% 이내였던데 비해 같은 유효염소 농도에서의 염소의 살균 반응 속도 상수는 E. coli 기준 17%, Enterococcus 기준 25% 감소하여 약 염기성인 선박평형수의 소독에 이산화염소가 염소에 비해 효과적임을 확인하였다. 또한 생태계를 교란할 수 있는 소독 부산물 생성에 있어서도 염소에 비해 현격히 낮은 결과를 보였다. 소독 후 장기 보관 시 30일까지는 지표 세균 및 플랑크톤의 재증식은 발견되지 않았다. 이산화염소는 선박평형수에 적합한 소독제로 판단된다.

• 상하수도학회지
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• 제30권5호
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• pp.587-596
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• 2016

This study attempts to draw factors for an analysis of the operation effect of a rechlorination facility and autodrain equipment for residual chlorine equalization by installing and operating a rechlorination facility and autodrain equipment in P City and analyzing the practical evaluation method and operation effect. For this purpose, this study selected three indicators for an analysis of the effectiveness of residual chlorine equalization and conducted a comparative analysis before and after the implementation of the residual chlorine equalization. As a result of estimation, (1) the reduction of the residual chlorine concentration range from a water treatment plant to the pipe end was 16.0%; (2) the total reduction of chlorination input was 18.0%; and (3) the reduction of the generation of disinfection by-products was 19.5%. In addition, this achieved enough residual chlorine equalization in the supply process and shows that it could successfully achieve the economic feasibility of investment in equipment and the reduction of the generation of disinfection by-products. Like this, it is judged that the three indicators suggested in this study will be used sufficiently as indicators of an analysis of the effectiveness of residual chlorine equalization according to the operations of the rechlorination facility and autodrain equipment.

• 한국물환경학회지
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• 제33권4호
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• pp.487-493
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• 2017

This study was conducted to propose measures of water quality management as the water criteria for waterscape facilities which have been highlighted as alternatives to wading pools in summer season was legislated. The number of public waterscape facilities has reached 290 sites in Gyeounggi province and 971 sites in South Korea in 2017. The water tank capacity of 80.3 % public waterscape facilities was less than $100m^3$. Facilities with disinfection system were only 6.5 % and facilities with filtration function were also very low at 6.9 %. Most of the waterscape facilities, about 93%, are expected to be vulnerable to complying with revised water quality criteria because they have to be disinfected by handling. Chlorine disinfectants, which are more persistent than ozone or ultraviolet sterilization methods, are more preferred. However, care should be taken when adding disinfectans because hypochlorous acid, which is an effective component of chlorine disinfectant, remains after the disinfection, but it is easily decomposed with time. For this study, ${\bigcirc}{\bigcirc}$ park floor fountain with a capacity of $63m^3$ was selected and the amount of free residual chlorine concentration was measured by injecting a certain amount of chlorine bleach. As a result, it took 5 hours to decrease from the water quality standard of 4 mg/L to 0.04 mg/L. If the waterscape facility is operated for 7 to 8 hours, the chlorine bleach should be re-injected after 5 hours. In addition, the problem of pH increase due to the input of chlorine disinfectant is expected, and the neutralization method using vinegar was proposed.

• 상하수도학회지
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• 제13권2호
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• pp.82-88
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• 1999

This study was to evaluate disinfection efficiency of chlorine and chloramine as secondary disinfectants in the distribution systems. Indicator organism, HPC in the suspended and attached were measured for copper, galvanized steel, PVC, and carbon steel pipes. For suspended microorganism, the PVC pipe was markedly dense among the assessed pipe materials. The attached microorganism was markedly equivalent roughness of pipe materials. In copper and galvanized pipes, chloramine was more effective that free chlorine to disinfect suspended microorganism in the contact time of 2 hours. The contact time for the 99% inactivation of suspended microorganism by chloramine was longer than that of free chlorine. Regardless of pipe materials, chloramine was effective on both disinfection efficiency and 99% inactivation time for attached microorganism. In conclusion, chloramine which is good disinfectant for long contact time was recommended as secondary disinfectant in distribution system.

• 한국환경과학회지
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• 제13권7호
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• pp.627-635
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• 2004

Evaluated were household THMs exposure associated with the use of municipal tap water treated with chlorine and with ozone-chlorine. The current study measured the THMs concentrations in the tap water and indoor and outdoor air in the two types of household, along with an estimation of THMs exposure from water ingestion, showering, and the inhalation of indoor air. Chloroform was the most abundant THMs in all three media, yet no bromoform was detected in any sample. Contrary to previous findings, the fall water THMs concentrations exhibited no significant difference between the chlorine and ozone-chlorine treated water. However, the spring median chloroform concentration in the tap water treated with chlorine (17.6 ppb) was 1.3 times higher than that in the tap water treated with ozone-chlorine (13.4 ppb). It is suggested that the effects of the water parameters should be considered when evaluating the advantage of ozone-chlorine disinfection for THMs formation over chlorine disinfection. The indoor air THMs concentration trend was also consistent with the water concentration trend, yet the outdoor air THMs concentrations did not differ significantly between the two types of household. The indoor to outdoor air concentration ratios were comparable with previous studies. The THMs exposure estimates from water ingestion, showering, and the inhalation of indoor air suggested that, for the residents living in the surveyed households, their exposure to THMs in the home was mostly associated with their household water use, rather than the indoor air. The THMs exposure estimates from tap water ingestion were similar to those from showering.

• 상하수도학회지
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• 제30권1호
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• pp.9-17
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• 2016

Disinfectant/oxidation process is a crucial process in water treatment for supplying safe drinking water. Chlorination is still widely used for water treatment area due to its effectiveness on microbial inactivation and economic feasibility. Recently, disinfection concern in marine environment is increasing, for example, movement of hazardous marine organism due to ballast water, marine environmental degradation due to power plant cooling water discharge, and increase of the amount of disinfectant in the offshore plant. It is needed to conduct the assessment of disinfectant behavior and the development of disinfectant prediction model in seawater. The appropriate prediction model for disinfectant behavior is not yet provided. The objective of the study is to develop chlorine decay model in seawater. Various model types were applied to develop the seawater chlorine decay model, such as first order decay model, EPA model, and two-phase model. The model simulation indicated that chlorine decay in seawater is influenced by both organic and inorganic matter in seawater. While inorganic matter has a negative correlation with the chlorine decay, organic matter has a positive correlation with the chlorine decay.

• 환경위생공학
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• 제24권2호
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• pp.40-48
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• 2009

Unusual bloom of toxic cyanobacteria in water bodies have drawn attention of environmentalists world over. Major bloom of Anabaena, Microcystis in water storage reservoir, rivers and lake leading to adverse health effects have been reported from Australia, England and many part of the world. These cyanobacterial cells can release intercellular matter like toxin in water and these intercellular matter can increase the concentration of organic matter. Cellysis can occur when algal cells meet the disinfectants like chlorine in water treatment plant and the resultant rising up of DOC(Dissolved Organic Carbon) or TOC(Total Organic Carbon) can increase the formation of disinfection by products. Disinfectants that kill microorganisms react with the organic or inorganic matter in raw water. In general disinfectants oxidize the matter in raw water and the resultant products can be harmful to human. There are always conflict about which is more important, disinfection or minimizing disinfection by products. The best treatment process for raw water is the process of the lowest disinfection by products and also the the lowest microorganism. In this study the cultured cells, Microcytis Aeruginosa(MA), Anabaena Flos-aquae(AF), Anabaena Cylindrica(AC), and the cells obtained in Daechung Dam(DC) whose dominant species was Anabaena Cylindrica were subjected to chlorination. Chlorination oxidizes inorganic and organic compounds and destruct live cells in raw water. Chloroform was analyzed for the cultured cells which were treated with $20mg/\ell$ dose of chlorine. In general chloroform is easily formed when dissolved organic matter react with chlorine. The cultured cells contributes the concentration of dissolved organic carbon and also that of total organic carbon which might be potent precusors of chloroform formed. The correlations of the concentration of chloroform, DOC and TOC were investigate in this study.

• 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.