• Journal of Korean Society of Environmental Engineers
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• v.35 no.11
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• pp.769-775
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• 2013

UV-induced transformations in the characteristics of dissolved organic matter (DOM) and the subsequent effects on the disinfection by-product formation potential (DBPFP) were investigated using the mixtures of the two humic substances with different sources, and two different size fractions of Suwannee River fulvic acid (SRFA). 7 day-photodegradation resulted in the decrease of specific ultraviolet absorbance (SUVA) of the mixtures as well as the specific DBPFP. After the irradiation, however, higher specific DBPFP values were consistently observed at the same range of the SUVA values. This suggests that non UV-absorbing components, generated by the UV-irradiation, may contribute to the formation of DBPs. Two different molecular size fractions of SRFA showed dissimilar responses to photodegradation. The behavior was also influenced by the types of the DBPs generated. Higher levels of trihalomethenes (THMs) were formed per organic carbon for the high molecular fraction compared to the low molecular fraction, whereas no differences were found in the formation of haloacetic acids (HAAs) between the two different size fractions. The formation of the two types of DBPs also differed by the irradiation times. Specific formation potential of THMs consistently increased upon the irradiation, whereas HAAs showed the initial increase followed by the decrease in their specific formation potential.

• Journal of Korean Society of Water and Wastewater
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• v.30 no.1
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• pp.69-75
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• 2016

This study was conducted to examine the byproducts formation characteristics at the water treatment plants which applying electrolysis as a disinfection process in Gangwondo, Korea. Total of forty plants located in Gangwon Province, Korea were selected for the study. Correlation between dissolved organic carbon(DOC) and $SUVA_{254}$ was not clear. Among the species of the disinfection byproducts(DBPs), chlorate and trihalomethanes(THMs) accounted for 76% and 14% of DBPs, respectively. The effect of DOC or $SUVA_{254}$ on DBPs formation was not clearly demonstrated. The increased amount of THMs due to the raw water bromide content was found primarily in the form of chloroform, and the percent fraction of BDCM(bromodichloromethane) and DBCM(Dibromochloromethnae) was relatively insignificant. When the value of $SUVA_{254}$ was greater than $2L/mg{\cdot}m$, the percent fraction of BDCM and DBCM decreased while percent fraction of CF(chloroform) increased.

• Communications for Statistical Applications and Methods
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• v.12 no.3
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• pp.557-587
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• 2005

This paper elucidates the limiting Gaussian distribution of a class of rank order statistics {$T_N$} for two sample problem pertaining to empirical processes of the squared residuals from two independent samples of GARCH processes. A distinctive feature is that, unlike the residuals of ARMA processes, the asymptotics of {$T_N$} depend on those of GARCH volatility estimators. Based on the asymptotics of {$T_N$}, we empirically assess the relative asymptotic efficiency and effect of the GARCH specification for some GARCH residual distributions. In contrast with the independent, identically distributed or ARMA settings, these studies illuminate some interesting features of GARCH residuals.

• Proceedings of the Korean Environmental Health Society Conference
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• 2005.06a
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• pp.259-262
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• 2005

This study aims to identify the relationship between characteristics of aqueous organic matter and chlorination by-products formation potential according to temporal effect of Juam reservoir in Sun-Choen. The molecular weight distribution and chemical composition of precursors and their relationship with disinfection by-products(DBPs) were investigated. Most of the organic matters was responsible for the major DBP precursors in the raw water are small compounds with a molecular weight less than IKDa, Aromatic contents determined by SUVA correlated well with DBPs, THMs, and HAAs formation. Especially, THMFP/DOC showed better correlation with SUVA than HAAFP/DOC and DBPFP/DOC with SUVA in Juam reservoir. Therefore, effective removal of small molecules or hydrophobic organic matter prior to disinfection process will significantly reduce the DBP concentration in the finished water.

• Journal of Korean Society of Water and Wastewater
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• v.18 no.6
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• pp.807-813
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• 2004

Wastewater was treated by two different treatment processes; activated sludge process and advanced wastewater treatment process (KNR process) using lab-scale experiment. Two treated wastewater showed good treatment efficiency of organic matter removal, up to 90% removal. Nitrogen and phosphorus were not effectively removed though activated sludge process, while KNR process showed good removal efficiency of nitrogen and phosphorus; 56% nitrogen removal and 95% phosphorus removal. KNR process showed better removal efficiency of organic matter, nitrogen, and phosphorus compared to activated sludge process. Organic matter characterization was tracked though measurement of UV scan, SUVA, and XAD fractionation. Treated wastewater showed higher SUVA value than wastewater influent, indicting less aromatic characteristic of organic matter. XAD fractionation showed hydrophilic fraction decreased though wastewater treatment, suggesting microbes preferentially digest hydrophilic and aliphatic molecules rather than hydrophobic and aromatic molecules of organic matter.

• Journal of Korean Society of Environmental Engineers
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• v.30 no.9
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• pp.893-899
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• 2008

Changes in spectroscopic characteristics and pyrene binding coefficients of terrestrial dissolved organic matters(DOM) were investigated during microbial incubation. The incubation studies were conducted for 21 days using a leaf litter DOM and a soilderived DOM with an inoculum from a river. The dissolved organic carbon(DOC), the specific UV absorbance(SUVA), the synchronous fluorescence spectra, and the pyrene organic carbon-normalized binding coefficient(K$_{oc}$) of the DOM were measured at the incubation days of 0, 3, 7, 14 and 21. After the 21-day incubation, DOC were reduced to 61% and 51% of the original concentrations of the litter DOM and the soil-derived DOM, respectively. Comparison of the spectroscopic characteristics before and after the incubation revealed that the SUVA, the fulvic-like fluorescence(FLF), the humic-like fluorescence(HLF) of the different DOM were enhanced by the incubation whereas the protein-like fluorescence(PLF) was reduced. This indicates that more aromatic and humic-like compounds were enriched during the biodegradation process while biodegradable and weak carbon structures were depleted. Irrespective of the DOM sources, SUVA values showed a positive relationship with pyrene K$_{oc}$ with a correlation coefficient of 0.97. The FLF and HLF also exhibited good correlations with K$_{oc}$ values although different regression equations were obtained from the different DOM. Our results suggest that the selected spectroscopic characteristics could be good estimation indices for the changes of the binding reactivity of DOM for hydrophobic organic contaminants during biodegradation process.

• Journal of Korean Society on Water Environment
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• v.21 no.2
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• pp.125-131
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• 2005

Natural organic matter(NOM) is defined as the complex matrix of organic material and abundant in natural waters. It affects the performance of unit operations for water purification. Several kinds of analytical indicators such as DOC, specific ultraviolet absorbance(SUVA), apparent molecular weight (AMW), fractionation and high performance size exclusive chromatography(HPSEC) have been used to understand characteristics and variations of NOM. This study aims to evaluate the characteristics of NOM in the Geum River system comprising with stream flows and reservoirs. It was identified that SUVA denoting the portion of humic substance in water ranged within 1.60~3.36. Using resin adsorbents, dissolved organic carbon(DOC) was fractionated into three classes: hydrophobic bases(HOB), hydrophobic acids(HOA) and hydrophilic substances(HI). HI dominates in all samples, collectively accounting for more than 62% of the DOC. HOA was the second dominated fraction and it varied considerably but accounted for about 30% of the DOC. The distribution of high molecular weight(HMW) measured by HPSEC being used to determine the molecular weight distribution of aquatic humic substances was 40.1% and 38.7% in reservoir and stream flow, respectively. The distribution of low molecular weight(LMW) in stream flow was 13.2% higher than that in reservoir. And apparent molecular weight less than 1KDa, which include the molecular weight of hydrophilic organic matter, occupied with 69.2% and 68.2% in stream flow and reservoir, respectively. While the molecular weight of 1 to 100 KDa including humic substances ranged with 18.6% and 21.6% in stream flow and reservoir, respectively. Seasonal variation of refractory dissolved organic carbon was similar to that of SUVA.

• Journal of Environmental Health Sciences
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• v.27 no.2
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• pp.92-99
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• 2001

This present study was aimed to investigate the characteristics of dissoloved organic matter (DOC) in sewage. The results are summarized as follows ; The plateaux reached in 3~4 days by the biodegradability test on sewage samples based on DOC. 쏭 rations of BDOC to DOC were 48, 21, 13 and 11% for raw sewage, primary treatment effluent, secondary treatment effluent and final treatment effluent, respectively. As the SUVA values ranged less 3L/m.mg for the effluent of sewage treatment plant, the DOC is composed largely of non-humic materials, hydrophilic, less aromatic as compared to waters with higher SUVA values. Through the biodegradability test, Dissolved organics showed that the quantity of LMW(Low Molecular Weight) less than 1,000 daltons was decreased, HMW(High Molecular Weight) more than 30,000 daltons had a tendency to increase. Large portion of UV$^{254}$ in final treatment effluent was increased of MMW(Medium Molecular Weight). Also, average removal efficiency of DOC was 32% during sewage treatment.

• Journal of Korean Society of Environmental Engineers
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• v.35 no.12
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• pp.861-866
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• 2013

The aim of this study was to investigate the biodegradation of dissolved organic matter derived from animal carcass disposal soil using soil inhabited bacteria and to identify the bacteria involved in the biodegradation. The two soils were obtained from the animal carcass burial sites located in Anseong, Gyeonggi-do, Korea. The results indicated that during the biodegradation experiments (56 days), 48% of dissolved organic carbon (DOC) was mineralized within 13 days in soil-derived solution 1 (initial DOC = 19.88 mgC/L), and the DOC concentration at 56 days was $8.8{\pm}0.4$ mg C/L, indicating 56% mineralization of DOC. In soil-derived solution 2 (initial DOC = 19.80 mgC/L), DOC was mineralized drastically within 13 days, and the DOC concentration was decreased to $6.0{\pm}0.4$ mg C/L at 56 days (76% mineralization of DOC). Unlike DOC value, the specific UV absorbance ($SUVA_{254}$) value, an indicator of proportion of aromatic structures in total organic carbon, tended to increase until 21 days and then decreased thereafter. The $SUVA_{254}$ values in soil-derived solutions 1 and 2 were the highest at 21 days. The microbial analysis demonstrated that Pseudomonas fluorescens, Achromobacter xylosoxidans, Nocardioides simplex, Pseudomonas mandelii, Bosea sp. were detected at 14 days of incubation, whereas Pseudomonas veronii appeared as a dominant species at 56 days.

• Journal of Environmental Health Sciences
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• v.33 no.2 s.95
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• pp.158-165
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• 2007

본 연구는 근원에 따른 용존 유기물의 특성을 평가하기 위해 하천수, 호소수, 하수 2차 처리 유출수의 자연수 및 Aldrich, Wako 사에서 공급된 휴믹산을 대상으로 분자량 분포에 따른 물리 화학적인 수질 특성, 생분해도, 소독, 부산물의 생성 등을 고찰하였다. SUVA를 이용해서 자연수의 생분해 가능성을 평가한 결과 호소수, 하수, 하천수 순으로 예측되었으며 이는, 실제 생분해도 실험 결과와 유사하였다 생분해 반응 중 저분자 영역대의 용존 유기물은 점차 감소하였고 반면에 고분자 영역대의 용존 유기물은 증가하였다. SMP는 전체 용존 유기물의 0.7-5.5%정도 관찰되었으며 고분자 물질을 많이 함유한 시료에서 높게 나타났다. THM 생성은 대체로 고분자 물질이 높을수록 증가하였으며 THMFP도 Wako 휴믹산을 제외한 샘플에서 이와 유사한 경향을 나타냈다.