• 상하수도학회지
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• 제21권6호
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• pp.653-661
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• 2007

The Disinfectants/Disinfection By-products (D/DBP) Rule proposed by the US Environmental Protection Agency requires the implementation of enhanced coagulation as a control strategy for natural organic matter (NOM) removal and as a means of limiting the formation of all DBPs, i.e., not just the trihalomethanes and haloacetica acids. To control DBP formation, several best available technologies (BATs) were determined for removal of DBPs and DBP precursors. The enhanced coagulation is one of the BATs for DBP precursors removal. Treatment facilities that achieve a specified percent removal of total organic carbon (TOC) prior to the application of a continuous disinfectant or that achieve a residual TOC concentration < 2mg/L prior to the application of a continuous disinfectant are considered to be in compliance with enhanced coagulation. The enhanced coagulation was applied to raw water in Korea, the Han River. Raw water were examined and effects of different raw water qualities on enhanced coagulation were investigated. Three analyses were used for raw water characteristics, water quality measurement, molecular weight distributions, hydrophobic/hydrophilic fractionation. The Han River had the relatively low alkalinity and low organic carbon concentration. The results of molecular weight distributions showed significant portions of low molecular weight organics, which is very different from most water in USA. The alum doses for the required TOC removal guided from USEPA manual were quite low (i.e. 10~30 mg/L alum) for the water, probably due to the specific water quality of the Han River.

• Environmental Analysis Health and Toxicology
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• 제12권3_4호
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• pp.31-41
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• 1997

Public concerns about hazardous health effect from the exposure to organic by-products of the chlorination have been increased. There are numerous studies reporting that chlorination of drinking water produces numerous chlorinated organic by-products including THMs, HAAs, HANs. Some of these products are known to be animal carcinogens. The purpose of this study was to estimate health risk of DBPs by chlorinated drinking water ingestion in Seoul based on methodologies that have been developed for conducting risk assessment of complex-chemical-mixture. The drinking water sample was collected seperately at six water treatment plant in Seoul at March, April, 1996. In tap water of households in Seoul, DBPs were measured wilfh the mean value of 36.6 $\mu$g/L. Risk assessment processes,. which include processes for the estimation of human cancer potency using animal bioassay data and calculation of human exposure, entail uncertainties. In the exposure assessment process, exposure scenarios with various assumptions could affect the exposure amount and excess cancer risk. The reference dose of haloacetonitriles was estimated to be 0.0023 mg/kg/day by applying dibromoacetonitrile NOAEL and uncertainty factor to the mean concentration. In the first case, human excess cancer risk was estimated by the US EPA method used to set the MCL (maximum contaminant level). In the second and third case, the risk was estimated for multi-route exposure with and without adopting Monte-Carlo simulation, respectively. In the second case, exposure input parameters and cancer potencies used probability distributions, and in the third case, those values used point estimates (mean, and maximum or 95% upper-bound value). As a result, while the excess cancer risk estimated by US EPA method considering only direct ingestion tended to be underestimated, the risk which was estimated by considering multi-route exposure without Monte-Carlo simulation and then using the maximum or 95% upper-bound value as input parameters tended to be overestimated. In risk assessment for Trihalomethanes, considering multi-route exposure with adopting Monte-Carlo analysis seems to provide the most reasonable estimations.

• 상하수도학회지
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• 제19권3호
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• pp.370-377
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• 2005

Dispersion of coagulant should be completed in a fraction of a second before the metal hydroxide precipitate has form. For the reason so-called pump diffusion flash mixing (PDFM) have been proposed, and PDFM is one of reasonable methods to quickly disperse the hydrolyzing metal salts. In this study, therefore, we attempt to understand the difference of removal characteristics of natural organic matter (NOM) between pump diffusion flash mixing (PDFM) and conventional rapid mixing (CRM) for coagulation in a water treatment system, and to enhance the removal of NOM through the improved mixing process. DOC and turbidity removal by PDFM higher than those by CRM, while SUVA value of water treated by PDFM was high as compared with that by CRM. Hydrophilic NOM was more effectively removed by PDFM than CRM, since charge neutralization effect increased by quick dispersion of coagulant. The DBP formation potentials due to NOM was effectively reduced by the improved mixing (i.e., PDFM) for coagulation and could be controlled through decrease in concentration of precursor rather than reduction of activity with disinfectant.

• 상하수도학회지
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• 제26권2호
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• pp.237-247
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• 2012

This study assessed the removal characteristics of taste and odor causing compounds (2-methylisoborneol and geosmin) and organic matters, using a pilot-scale ozone/granular activated carbon ($O_{3}$/GAC) process treating surface water of Pal-dang reservoir in the Han river over a 3-month period. Experiments were conducted to verify the removal efficiency of $O_{3}$/GAC process which has two different empty bed contact time (EBCT) ($O_{3}$/GAC column 1 : 10 min and 2 : 15.1 min) with 10.86 min contact time of ozonation at 1.0 mg/L $O_{3}$. Spiking test using geosmin and 2-MIB was also conducted systematically to mimic the conditions when the algae appears, specifically at the levels similar to the concentrations experienced (geosmin: 250 ng/L) in the winter of 2011. In single ozonation process, organic materials, disinfection by-products (DBPs) and their precursors were disassembled but not removed completely. Meanwhile, it was verified that organic matters, taste and odor causing compounds, and DBPs were well removed when sequentially passing through the GAC process. The pilot results also showed that GAC column with larger EBCT achieved higher removal efficiency. Specifically, in spiking tests, single $O_{3}$ process showed approximately 89% removal efficiency of geosmin and 2-MIB. $O_{3}$/GAC combined process demonstrated excellent removal of geosmin and 2-MIB, which are higher than 95%.

• 한국환경독성학회:학술대회논문집
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• 한국환경독성학회 1996년도 제19회정기학술대회(The 19th Symposium of the Korean Society of Environmental Toxicology)
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• pp.75-75
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• 1996

최근 가장 관심이 집중되고 있는 음용수중의 미량오염물질로는 인위적으로 첨가되는 소독제(disi octant)로 인한 소독부산물(disinfection by-products: DBPs)을 들 수 있다. 1970년대부터 염소소독시 수중의 유기오염물길과 반응하여 발암성물질 과 돌연변이 물질이 다수 함유되어 있는 클로로포름(chloform)을 포함한 트리할로메탄(Trih리omethane: THMs)의 생성이 발견되었으며 이로 인한 건강상의 영향이 지속적으로 보고되고 있다. 염소소독시 780가지 이상의 화합물이 염소와 휴믹산(humic acids)과의 반응에 의해 생성되며, 이중 대부분이 할로겐 화합물로 알려져 있다. 염소 소독부산물로는 인체발암력을 지니고 있는 트리할로메탄(THMs) 이외에도 할로아세틱산(Haloaceticacids: HAAs), 할로아세토나이트릴(Haloacetbnitriles: HANs)등이 주 생성물질인 것으로 알려져 있으나 우러나라의 원수특성에 따른 소독부산물의 생성능 (Formation potential)에 대한 연구가 미흡한 실정이다. 본 연구에서는 우리나라 주요 4대강(한강, 대청호, 영산강, 낙동강)의 원수를 실험실내에서 염소처리하여 생성되는 소독부산물의 생성농과 pH, 체류시간 등의 조건에 따라 생성능을 조사하였다. 각 화합물은 추출 및 농축과정을 거친 후 GC/MSD를 사용하여 물질을 확인한 후 할로겐화합물에 민감한 GC/ECD를 사용하여 시료를 분석하였다. pH와 시간, 원수중의 유기물 함량이 소독부산물의 생성에 많은 영향을 미치는 것으로 나타났다. THMs은 알칼리에서, HAAs의 경우는 약산성에서 접촉시간이 증가할수록 높은 생성능을 보였고, HANs의 경우는 급속히 생성했다가 시간이 경과함에 따라 소멸하며 약산성에서 높은 생성능을 보임을 알 수 있었다, 강별로는 낙동강에서 THMs파 HANs의 생성능이 비교적 높았고, 영산강에서는 HAAs의 생성능이 높았다. 각 원수의 특성에 따른 생성능을 파악함으로써 생성능 저감방안을 마련하며, 소독 부산물질의 인체노출평가에 따른 위해성평가를 통해 관리기준을 설정해야 할 것이다.

• 한국방재학회:학술대회논문집
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• 한국방재학회 2008년도 정기총회 및 학술발표대회
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• pp.417-420
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• 2008

Recently, the interest in NDMA(N-nitrosodimethylamine) has increased due to its recognition as a pollutant by Ontario Ministry of Environment and Energy and California Department of Health Sciences. It is, in fact, one of the DBPs(Disinfection By-products) which appears due to chlorination and is reported to be fatal if exposed continuously to human body. Due to uncertainty in mechanism to remove it, its treatment is not yet carried out. In this experiment, treatment of biological NDMA is carried out by letting it adsorbed on Granular Sludge and then filtering the medium through MF(Microfiltration) and UF(Ultrafiltration) membranes. Granular Sludge is adapted to aerobic and anaerobic conditions for 7 days and the experimental conditions are MLSS of 8000mg/L, COD of 250mg/L, TN of 12.5mg/L, and TP of 2.5mg/L. Several batch tests were carried out and samples were collected with the interval of 1 hour. Samples were measured by LSC(Liquid scintillation counter) after filtering by MF and UF. In batch test with granular sludge the permeate concentrations(removal efficiencies) of NDMA by MF and UF were 71.7ng/L(32.0%) and 62.0ng/L(43.7%) at aerobic state, and 52.0ng/L(49.2%) and 47.6ng/L(58.9%) at anaerobic state, respectively. Hence, UF membrane showed about 10% more removal efficiency than MF and removal efficiency at anaerobic condition was 15% more than that at aerobic condition.

• 한국환경과학회지
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• 제23권9호
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• pp.1655-1662
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• 2014

A comprehensive fractionation technique was applied to a set of water samples obtained along drinking water treatment process with ozonation and biological activated carbon (BAC) process to obtain detailed profiles of dissolved organic matter (DOM) and to evaluate the haloacetic acid (HAA) formation potentials of these DOM fractions. The results indicated that coagulation-sedimentation-sand filtration treatment showed limited ability to remove hydrophilic fraction (28%), while removal of hydrophobic and transphilic fraction were 57% and 40%, respectively. And ozonation and BAC treatment showed limited ability to remove hydrophobic fractions (6%), while removal of hydrophilic and transphilic fractions were 25% and 18%. The haloacetic acid formation potential (HAAFP)/dissolved organic carbon (DOC) of hydrophilic fraction was the highest along the treatment train and HAAFP/DOC of hydrophilic fraction was higher than hydrophobic and transphilic fraction as 23%~30%, because of better removal for hydrophobic fraction both in concentration and reactivity.

• 한국환경과학회지
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• 제24권1호
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• pp.65-71
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• 2015

This study accessed the adsorption characteristics of the 9 trihalomethanes (THMs) on coal-based granular activated carbon (GAC). The breakthrough appeared first for $CHCl_3$ and sequentially for $CHBr_2Cl$, $CHBr_3$, $CHCl_2I$, CHBrClI, $CHBr_2I$, $CHClI_2$, $CHBrI_2$, and $CHI_3$. The maximum adsorption capacity (X/M) for the 9 THMs with apparent breakthrough points ranged from $1,175{\mu}g/g$ (for $CHCl_3$) to $11,087{\mu}g/g$ (for $CHI_3$). Carbon usage rate (CUR) for $CHCl_3$ was 0.149 g/day, 5.5 times higher than for $CHCl_3$ (0.027 g/day).

• 대한환경공학회지
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• 제29권4호
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• pp.412-418
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• 2007

THM 생성은 염소접촉 후 4시간까지 선형적인 증가추세를 보이며, 많은 양의 THM이 생성되는 것으로 나타났으며, 반응 30분만에 168시간 동안 생성된 양의 총 $25\sim43%$의 비율을 차지하였다. 또한, 수중의 브롬이온 농도에 따른 THM 생성특성 조사에서 유기성 전구물질인 humic acid의 농도는 일정하고, 브롬이온의 농도만 $0\sim50{\mu}g/L$까지 변화시켜 염소처리하였을 경우에는 생성되는 총 THM의 농도는 접촉시간 별로 큰 차이가 없는 것으로 나타났다. 수온변화에 따른 THM 생성특성 조사에서 수온이 낮은 $4^{\circ}C$일 때는 PF(parabolic formation) phase로 접어들어서도 THM 생성량이 계속적으로 증가하는 양상을 나타내었으며, $20^{\circ}C$와 $35^{\circ}C$의 경우에는 IF(instantaneous formation) phase까지 급격한 증가추세를 보인 후 PF phase에 도달하여서는 그 증가추세가 둔화되는 것으로 나타났다. pH 변화에 따른 THM 생성특성 조사에서 pH가 5일 경우 IF phase까지 증가추세를 보인 후, PF phase로 접어들어서도 계속적으로 증가하는 것으로 나타났지만 pH가 7과 pH가 9의 경우에는 IF phase까지 급격한 증가추세를 보인 후 PF phase에 도달하여서는 그 증가 경향이 아주 둔화되는 것을 볼 수 있으며, 이런 현상은 pH가 9일 경우에는 더욱 두드러지게 나타났다.

• 대한환경공학회지
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• 제32권5호
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• pp.523-530
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• 2010

14종의 합성유기질소 화합물들에서의 염소 소독부산물 생성 특성을 조사한 결과, 단위 DOC당 THM 생성능은 $Br^-$첨가 유무에 관계없이 3-aminobenzoic acid, 2-aminophenol, aniline, anthranilic acid 및 4-nitroaniline에서 높게 나타났다. 단위 DOC당 HAA 생성능 조사결과, $Br^-$ 첨가 유무에 관계없이 단위 DOC당 THM 생성능과 유사한 생성특성을 보였으나 특이하게 p-nitrophenol에서 가장 높은 생성능을 나타내었으며, 생성된 HAAFP의 대부분이 TCAAFP로 나타났다. 단위 DOC당 HAN 생성능은 3-aminobenzoic acid, 2-aminophenol, aniline 및 anthranilic acid에서 $Br^-$ 첨가 유무에 관계없이 높은 생성능을 나타내었고 다른 합성유기질소 화합물들에 비해 aniline에서 높은 생성능을 보였으며, 반응성이 높은 4종의 합성유기질소 화합물들에서 생성되는 HAN 구성종의 대부분은 DCAN으로 나타났다. 단위 DOC당 chloral hydrate와 chloropicrin의 생성능을 조사결과에서 3-aminobenzoic acid와 2-aminophenol에서 생성능이 높은 것으로 나타났고, 전체적으로 10 $mg/{\mu}g$ 이하의 비교적 낮은 생성능을 보였다. 염소 소독부산물 생성능이 높은 6종의 합성유기질소 화합물들과 시판 humic acid에서의 $Br^-$ 첨가 유무에 따른 단위 DOC 당 총 DBP 생성능을 조사한 결과에서 $Br^-$를 첨가한 경우는 anilin e> anthranilic acid> 3-aminobenzoic acid> 4-nitroaniline> humic acid> p-nitrophenol> 2-aminophenol 순으로 나타났고, $Br^-$를 첨가하지 않은 경우는 anthranilic acid> aniline> p-nitrophenol> humic acid> 4-nitroaniline> 3-aminobenzoic acid> 2-aminophenol 순으로 조사되었다. 또한, aniline, anthranilic acid, 4-nitroaniline 및 p-nitrophenol의 경우는 염소와의 반응성이 아주 높은 것으로 조사되었다.