Hoon-Sik Yoom

Detection of Perfluorinated Compounds (PFCs) in Nakdong River Basin

The aims of this study were to investigate and confirm the occurrence and distribution patterns of perfluorinated compounds (PFCs) in Nakdong River basin (mainstream and its tributaries). 7 (PFOS, PFHpA, PFOA, PFNA, PFDA, PFUnDA and PFDoDA) out of 11 PFCs were detected in 29 sampling sites and PFOA and PFHpA were predominant compounds in upstream, but PFUnDA, PFDoDA and PFOS were predominant compounds in middle stream of Nakdong River basin. The total concentration levels of PFCs on February 2009 and on August 2009 in surface water samples ranged from 4.3. to 1168.2 ng/L and 16.4 to 627.8 ng/L, respectively. The highest concentration level of PFCs in the mainstream and tributaries in Nakdong River were Goryeong and Jincheon-cheon, respectively. The sewage treatment plants (STPs) along the river affect the PFCs levels in river and the PFCs levels decreased with downstream because of dilution effects.

Application of On-Line SPE-LC/MSD to Measure Perfluorinated Compounds (PFCs) in Water

We applied a sensitive method based on on-line solid-phase extraction (SPE) and liquid chromatography/mass spectrometry (LC/MSD) using an electrospray interface for the determination of eleven perfluorinated compounds (PFCs) in water. The on-line connection suppressed the target loss by keeping the cartridge from drying, which resulted in improvement of the recovery and saving of the analytical time. For the on-line solid-phase extraction of 10 mL water samples, recoveries were between 80.4 ± 5.2%~109.5 ± 1.4% and limit of quantification (LOQ) were 3.6~15.9 ng/L for the PFCs. The total PFCs concentrations of the tributaries and main stream of Nakdong River water samples were in the range of 8.0~678.6 μg/L.

Analysis of Trace Levels of Lodinated Trihalomethanes in Water Using Headspace - GC/ECD

Abstract : Trihalomethanes (THMs) are formed as a results of the reaction of residual chlorine, used as a disinfectant in drinking water, with the organic matter in raw water. Although chlorinated and brominated THMs are the most common disinfection by- products (DBPs) reported, iodinated THMs (I-THMs) can be formed when iodide is present in raw water. I-THMs have been usually associated with several medicinal or pharmaceutical taste and odor problems and is a potential health concern since they have been reported to be more toxic than their brominated and chlorinated analogs. Currently, there is no published standard ana-lytical method for I-THMs in water. An automated headspace-gas chromatography/electron capture detector (GC/ECD) technique was developed for routine analysis of 10 THMs including 6 I-THMs in water samples. The optimization of the method is discussed. The limits of detection (LOD) and limits of quantification (LOQ) range from 12 ng/L to 56 ng/L and from 38 ng/L to 178 ng/L for 10 THMs, respectively. Matrix effects in river water, sea water and wastewater treatment plant (WWTP) final effluent water were investigated and it was shown that the method is suitable for the analysis of trace levels of I-THMs, in a wide range of waters. The method developed in the present study has the advantage of being rapid, simple and sensitive.

Analysis of Synthetic Fragrances (SFs) in Water Using Stir Bar Sorptive Extraction (SBSE) and GC-MS/MS

A highly sensitive analytical method based on stir bar sorptive extraction (SBSE) technique and gas chromatography/ tandem mass spectrometry (GC-MS/MS) has been developed, allowing the simultaneous multi-analyte determination of 11 synthetic fragrances (SFs) in water samples. The stir bar coated with polydimethylsiloxane (PDMS) was added to 40 mL of water sample at pH 3 and stirred at 1,100 rpm for 120 min. Other SBSE parameters (salt effect and presence of organic solvent) were optimised. The method shows good linearity (coefficients > 0.990) and reproducibility (RSD < 10.9%). The extraction efficiencies were above 83% for all the compounds. The limits of detections (LOD) and limits of quantification (LOQ) were 2.1~4.1 ng/L and 6.6~12.9 ng/L, respectively. The developed method offers the ability to detect 11 SFs at ultra-low concentration levels with only 40 mL of sample volume. Matrix effects in tap water, river water, wastewater treatment plant (WWTP) final effluent water and seawater were investigated and it was shown that the method is suitable for the analysis of trace level of 11 SFs. The method developed in the present study has the advantage of being rapid, simple, high-sensitive and both user and environmentally friendly.

Transformation of methylparaben during water chlorination: Effects of bromide and dissolved organic matter on reaction kinetics and transformation pathways

The reaction kinetics, products, and pathways of methylparaben (MeP) during water chlorination with and without bromide (Br-) were investigated to better understand the fate of parabens in chlorinated waters. During the chlorination of MeP-spiked waters without Br-, MeP was transformed into mono-Cl-MeP and di-Cl-MeP with apparent second-order rate constants (kapp) of 64M-1s-1 and 243M-1s-1 at pH7, respectively, while further chlorination of di-Cl-MeP was relatively slower (kapp=1.3M-1s-1 at pH7). With increasing Br- concentration, brominated MePs, such as mono-Br-MeP, Br-Cl-MeP, and di-Br-MeP, became major transformation products. The di-halogenated MePs (di-Cl-MeP, Br,Cl-MeP, and di-Br-MeP) showed relatively low reactivity to chlorine at pH7 (kapp=1.3-4.6M-1s-1) and bromine (kapp=32-71M-1s-1), which explains the observed high stability of di-halogenated MePs in chlorinated waters. With increasing pH from 7 to 8.5, the transformation of di-halogenated MePs was further slowed due to the decreasing reactivity of di-MePs to chlorine. The formation of the di-halogenated MePs and their further transformation become considerably faster at Br- concentrations higher than 0.5μM (40μg/L). Nonetheless, the accelerating effect of Br- diminishes in the presence of dissolved organic matter (DOM) extract (Suwannee River humic acid (SRHA)) due to a more rapid consumption of bromine by DOM than chlorine. The effect of Br- on the fate of MeP was less in the tested real water matrices, possibly due to a more rapid bromine consumption by the real water DOM compared to SRHA. A kinetic model was developed based on the determined species-specific second-order rate constants for chlorination/bromination of MeP and its chlorinated and brominated MePs and the transformation pathway information, which could reasonably simulate the transformation of MePs during the chlorination of water in the presence of Br- and selected DOM.

Synthetic Musk Compounds Removal Using Biological Activated Carbon Process in Drinking Water Treatment

In this study, The effects of three different biological activated carbon (BAC) materials (each coal, coconut and wood based activated carbons) and anthracite, empty bed contact time (EBCT) and water temperature on the removal of MK, HHCB and AHTN in BAC filters were investigated. Experiments were conducted at three water temperatures (5, 15 and 25°C) and four EBCTs (5, 10, 15 and 20 min). The results indicated that coal based BAC retained more attached bacterial biomass on the surface of the activated carbon than the other BAC, increasing EBCT or increasing water temperature increased the synthetic musk compounds (SMCs) removal in BAC columns. The kinetic analysis suggested a first-order reaction model for MK, HHCB and AHTN removal at various water temperatures (5, 15 and 25°C). The pseudo-first-order biodegradation rate constants and half-lives were also calculated for MK, HHCB and AHTN removal at 5, 15 and 25°C. The pseudo-first-order biodegradation rate constants and half-lives of MK, HHCB and AHTN ranging from 0.0082 min to 0.4452 min and from 1.56 min to 84.51 min could be used to assist water utilities in designing and operating BAC filters for SMCs removal.

Occurrence of X-ray Contrast Media (Iopromide) in the Nakdong River Basin

The aims of this study were to investigate and confirm the occurrence and distribution patterns of iodinated X-ray contrast media (iopromide) in Nakdong river basin (mainstream and its tributaries). Iopromide was detected in 16 sampling sites. The concentration levels of iopromide on February 2011 and on October 2011 in surface water samples ranged from not detected (ND) to 1481.1 ng/L and ND to 1168.2 ng/L, respectively. The highest concentration level of iopromide in the mainstream and tributaries in Nakdong river were Goryeong and Jincheon-cheon, respectively. The sewage treatment plants (STPs) along the river affect the iopromide levels in river and the iopromide levels decreased with downstream because of dilution effects.

Occurrence Characteristics of Parabens in Nakdong River Basin

In this study, methyl paraben (MP), ethyl paraben (EP), propyl paraben (PP), and butyl paraben (BP) were analyzed to identify their occurrence characteristics at various sampling sites (the effluent from the wastewater treatment plant, the main stream and tributaries to which the effluent is introduced) in the Nakdong River basin during various sampling periods (January, April, August, and October). Among the four parabens, MP was detected with the highest detection frequency (100%), followed by PP (80~100%), EP (13~43%), and BP (3~20%). In case of detection level, MP showed the highest concentration with 3.2 to 33.9 ng/L as an average, followed by PP (8.2 to 28.4 ng/L), EP (2.2 to 8.0 ng/L), and BP (1.0 to 2.4 ng/L). In August, when the use of personal care products increased sharply, parabens that had not been completely removed from the wastewater flowed into the water system and showed typical patterns of contamination of the water sources. At the upstream sites, the detection level of the parabens was relatively lower than other sites, but the parabens were found to be high in the tributaries and the main stream from the midstream where the wastewater treatment plants were densely located. For discharge loads calculated using effluent concentration, large wastewater treatment plants with a treatment capacity of 100,000 ton/day or more were the major contamination pathway of parabens in the Nakdong River basin. The results of calculations of non-carcinogenic risk for parabens detected in the main stream of Nakdong River, tributaries and wastewater treatment plants were evaluated as no risk, but long-term monitoring and management were required for long-term toxicity in water environment.

Evaluation of Biodegradation Kinetic in Biological Activated Carbon (BAC) Process for Drinking Waste Treatment : Effects of EBCT and Water Temperature

In this study, the effects of empty bed contact time (EBCT) and water temperature on the biodegradation of 9 halonitromethanes (HNMs) in biological activated carbon (BAC) process were investigated. Experiments were conducted at three water temperatures (10°C, 15°C and 25°C) and three EBCTs (5, 10 and 15 min). Increasing EBCT and water temperature increased the biodegradation efficiency of HNMs in BAC column. Dibromochloronitromethane (DBCNM) and tribromonitromethane (TBNM) showed the highest biodegradation efficiency, but chloronitromethane (CNM) and dichloronitromethane (DCNM) were the lowest. The kinetic analysis suggested a pseudo-first-order reaction model for biodegradation of 7 HNMs at various water temperatures and EBCTs. The pseudo-first-order biodegradation rate constants (kbio) of 7 HNMs ranged from 0.0797~0.7657 min at 10°C to 0.1245~1.8421 min at 25°C. By increasing the water temperature from 10°C to 25°C, the biodegradation rate constants (kbio) were increased 1.6~2.4 times.

Adsorption Characteristics of Iodo-Trihalomethanes (I-THMs) in Granular Activated Carbon (GAC) Adsorption Process

Abstract 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 2 Cl, CHBr 3 , CHCl 2 I, CHBrClI, CHBr 2 I, 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 μg/g (for CHCl 3 ) to 11,087 μg/g (for CHI 3 ). Carbon usage rate (CUR) for CHCl 3 was 0.149 g/day, 5.5 times higher than for CHI 3 (0.027 g/day). Key words : Iodo-Trihalomethanes (I-THMs), Disinfection By-Products (DBPs), Granualr Activated Carbon (GAC), Adsorption. 1. 서 론 1) 정수처리 공정에서 소독 및 살균의 목적으로 사용되는 염소는 발암성 및 돌연변이성을 나타내는 다양한 소독부산물들을 생성시킨다. 특히, 트리할로메탄류(trihalo -methanes, THMs)는 할로아세틱엑시드류(haloacetic acids, HAAs)나 할로아세토니트릴류(haloacetonitriles, HANs)에 비해 비교적 높은 농도로 생성되며, 이들은 활성탄 흡착이나 생물분해와 같은 정수처리 공정에서 쉽게 제거하기 어려운 물질들이다(Son 등, 2005).최근에는 요오드계 THMs (I-THMs)에 대한 관심이 고조되고 있다. I-THMs는 요오드 이온(I - )이 함유된 물을 염소 또는 오존처리시 생성이 되며(Bichsel과 von Gunten, 2000; Hua 등, 2006), 염소계나 브롬계 THMs 보다 생체독성과 발암성이 강한 것으로 알려져 있다(Plewa 등, 2004; Richardson 등, 2008). 특히, iodoform이 함유된 물은 심한 약품취를 유발하여 먹는물에 대한 불신을 초래한다(Hansson 등, 1987). I-THMs의 역취농도 범위는 물질별로 0.03 8.9 μg/L 정도로 알려져 있으며, iodoform의 역취농도가 가장 낮아서 미량의 iodoform이 함유된 물에서도 약품취를 유발한다(Cancho 등, 2001).I-THMs의 생성기작은 수중의 요오드 이온(I