Jin-Taek Choi

Analysis of UV Filters 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 seven UV filters 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 < 12.9%). The extraction efficiencies were above 84% for all the compounds. The limits of detections (LOD) and limits of quantification (LOQ) were 2.1∼8.6 ng/L and 6.8∼27.5 ng/L, respectively. The developed method offers the ability to detect 8 UV filters 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 7 UV filters except of benzophenone (BP). The method developed in the present study has the advantage of being rapid, simple, high-sensitive and both user and environmentally friendly.

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.

Biodegradation of UV Filters in Biological Activated Carbon (BAC) Process : Biodegradation Kinetic

In this study, The effects of empty bed contact time (EBCT) and water temperature on the biodegradation of 8 UV filters in biological activated carbon (BAC) process were investigated. Experiments were conducted at two water temperatures (7 and 18°C) and three EBCTs (5, 10 and 15 min). Increasing EBCT and water temperature increased the biodegradation efficiency of UV filters in BAC column. EHMC and BZC were the highest biodegradation efficiency, but BP and 4-MBC were the lowest. The kinetic analysis suggested a first-order reaction model for biodegradation of 8 UV filters at various water temperatures and EBCTs. The first-order biodegradation rate constants (kbio) of 8 UV filters ranging from 0.2730~0.6365 min at 7°C to 0.4824~ 0.8743 min at 18°C. By increasing the water temperature from 7°C to 18°C, the biodegradation rate constants (kbio) were increased 1.5~2.1 times.

Evaluation of Applicability and Economical Efficiency of Peroxone Process for Removal of Micropollutants in Drinking Water Treatment

Abstract We compared the applicability and economical efficiency of peroxone process with those of ozone process in the existing water treatment plant on downstream of Nakdong River. After comparing the peroxone process for removing geosmin with the ozone process in lab scale test, peroxone process showed much higher removal efficiency than the ozone process at the same ozone dosage. Proper range of H 2 O 2 /O 3 ratio were 0.5~1.0 and the half-life of geosmin was about 5.5~6.8 min when the H 2 O 2 /O 3 ratio was set to 0.5 during 1~2 mg/L of ozone dosage. Peroxone process could reduce the ozone dosage about 50 to maximum 30% for the same geosmin removal efficiency compared to the ozone process in the pilot scale test. In case of 1,4-dioxane treatment, peroxone process could have 3~4 times higher efficiency than ozone process at the same ozone dosage. The results of estimating the economical efficiency of ozone and peroxone process for treating geosmin and 1,4-dioxane by using pilot scale test, in case of the removal target was set to 85% for these two materials, the cost of peroxane process could be reduced about 1.5 times compared to ozone process, and in the same production cost peroxone process could have 2~3 times higher removal efficiency than ozone process. The removal efficiency by peroxone process showed a large difference depending on the physicochemical characteristics of target materials and raw water, therefore detailed examination should be carried out before appling peroxone process. Key words: Peroxone process, Geosmin. 1,4-dioxane, Drinking water treatment, Economical efficiency

Application of Enhanced Coagulation for Nakdong River Water Using Aluminium and Ferric Salt Coagulants

Enhanced coagulation is best available technologies to treat NOM in water to produce clean drinking water. In this research, the comparison experiments between conventional coagulation (CC) and enhanced coagulation (EC) using 4 type coa- gulants i.e., ferric chloride, aluminium sulphate (alum), poly aluminium sulphate organic magnesium (PSOM) and poly aluminium chloride (PACl) were performed in terms of surrogate parameters such as dissolved organic carbon (DOC), trihalomethane formation potential (THMFP), haloacetic acid formation potential (HAAFP) and zeta potential variation in order to find out the most effective coagulant and conditions to fit Nakdong River water. When applied to EC process, the turbidity removal efficiency did not increased gradually compared to the CC process when adding coagulants. Furthermore, the removal efficiency of turbidity became decreased much more as coagulants were added increasingly whereas the removal efficiency of DOC, THMFP and HAAFP became increased by 13~18%, 9~18% and 9~18% respectively compared to the CC process. The characteristics of turbidity removal showed relatively high removal efficiency considering the pH variation in entire pH range when using FeCl3 and PACl. Additionally, in case of alum and PSOM steady removal efficiency was shown between pH 5 and pH 8. In terms of DOC surrogate the coagulants including 4 type coagulants indicated high removal efficiency between pH 5 and pH 7. The removal efficiency of dissolved organic matter (DOM) in EC between less than 1 kDa and more than 10 kDa augmented by 11~21% and 16% respectively compared to the CC process. The removal efficiency of hydrophobic and hydrophilic organic matter proved to be increased by 27~38% and 11~15% respectively. In conclusion, the most effective coagulant relating to EC for Nakdong River water was proved to be FeCl3 followed by PSOM, PAC and alum in order.

Occurrence of Organophosphorus Flame Retardants (OPFRs) in Nakdong River Basin : Mainstreams, Tributaries and STP Effluents

This study was investigated occurrence and distribution patterns of organophosphorus flame retardants (OPFRs) in Nakdong River basin (mainstream, tributaries and sewage treatment plant (STP) effluents). 3 (TCEP, TCPP and TBEP) out of 9 OPFRs were detected in 6 out of 20 sampling sites (mainstream and tributaries), The TCPP and TBEP concentration levels in mainstream samples were ND~114.9 ng/L ng/L and ND~49.1 ng/L, respectively. And the TCEP, TCPP and TBEP concentration levels in tributary samples were ND~1,865.3 ng/L, ND~519.2 ng/L and ND~210.4 ng/L, respectively. 4 (TBP, TCEP, TCPP and TBEP) out of 9 OPFRs were detected in effluents of 11 STPs around the Nakdong River basin. The TBP, TCEP, TCPP and TBEP concentration levels in 11 STP effluents were ND~458.5 ng/L, ND~2,932.7 ng/L, ND~1,320.7 ng/L and ND~655.2 ng/L, respectively. According to the sampling season, change ranges of distribution patterns and detected concentrations of OPFRs were highly variable in the same sampling sites.

Evaluation of Adsorption Characteristics of Radioactive Iodine (I-131) for Various Materials of Granular Activated Carbon (GAC)

Abstract This research was performed by means of several different virgin granular activated carbons (GAC) made of each coal, coconut and wood, and the GACs were investigated for an adsorption performance of iodine-131 in a continuous adsorption column. Breakthrough behavior was investigated that the breakthrough points of the virgin two coals-, coconut- and wood-based GACs were observed as bed volume (BV) 7080, BV 5640, BV 5064 and BV 3192, respectively. The experimental results of adsorption capacity (X/M) for iodine-127 showed that two coal- based GACs were highest (208.6 and 139.1 μg/g), the coconut-based GAC was intermediate (86.5 μg/g) and the wood-based GAC was lowest (54.5 μg/g). The X/M of the coal-based GACs was 2∼4 times higher than the X/M of the coconut-based and wood-based GACs. Key words : Iodine-131, Radionuclide, Granular activated carbon (GAC), Adsorption. 1. 서 론 1) 수중에 함유되어 있는 방사성 물질은 물을 직접 음용함으로서 인체 내로 유입되거나 또는 수중에 서식하는 생물들의 먹이 사슬을 통한 간접적인 방법으로 인체에 흡수될 수 있다. 요오드(I)는 갑상선 호르몬 성분으로 인간과 동물에 필수적인 원소이며, 자연 상태에서는 I-127과 I-129의 동위원소로 이루어져 환경 중에 흔하게 존재한다. 그러나 I-131은 자연 상태에서는 존재하지 않고, 우라늄의 핵분열 과정에서 발생하며, 핵사고시에 환경 중으로 방출되는 매우 위험한 인공 방사성핵종으로 1986년 4월 23일 체르노빌 원전사고 후 원전 주위에서 갑상선암 발병의 증가가 확인되었다(Goossens 등, 1989). 2011년 3월 일본 대지진으로 도쿄 전력의 후쿠시마 다이치 원전의 폭발로 인해 많은 양의 인공방사성핵종이 환경중으로 방출되었으며(Ikemoto와 Magara, 2011), 환경 중으로 방출된 주요 방사성핵종은 Te-132(반감기, 77 hr), Te-131(반감기, 24.8 min) 그리고 그들의 딸핵인 I-131(반감기, 8.05 day), Cs-134(반감기, 2.06 yr), Cs-137(반감기, 30 yr)이었으며, 원전 폭발 후에 I-131이 일본의 먹는물(수돗물)에서 검출되었다(Ikemoto와

A Study on the Correlation between Odorous Compounds, Actinomycetes and Algae in Drinking Water Source of Nakdong River

We have investigated the correlation between odorous compounds and actinomycetes in drinking water source of Nakdong River in 2011. Geosmin was mainly detected in the spring and summer seasons (Mar, Aug, and Sep) and 2-MIB was mainly detected in the winter and spring seasons (Feb, Mar and May). The odorous compounds concentrations were highest on March which also overlapped with the peak of actinomycetes, geosmin and 2-MIB were detected highly in the diluted culture solution of isolated actinomycetes strains from Nakdong River. For these reasons we could confirm that odorous compounds on March and August are closely related with actinomycetes. Meanwhile, geosmin increase on September supposed to relate with Microcystis.

Evaluation of Natural Organic Matter Treatability and Disinfection By-Products Formation Potential using Model Compounds

While a range of natural organic matter (NOM) types can generate high levels of disinfection by-products (DBPs) after chlorination, there is little understanding of which specific compounds act as precursors. Use of eight model compounds allows linking of explicit properties to treatability and DBP formation potential (DBPFP). The removal of model compounds by various treatment processes and their haloacetic acid formation potential (HAAFP) before and after treatment were recorded. The model compounds comprised a range of hydrophobic (HPO) and hydrophilic (HPI) neutral and anionic compounds. On the treatment processes, an ozone oxidation process was moderate for control of model compounds, while the HPO-neutral compound was most treatable with activated carbon process. Biodegradation was successful in removing amino acids, while coagulation and ion exchange process had little effect on neutral molecules. Although compared with the HPO compounds the HPI compounds had low HAAFP the ozone oxidation and biodegradation were capable of increasing their HAAFP. In situations where neutral or HPI molecules have high DBPFP additional treatments may be required to remove recalcitrant NOM and control DBPs.

Decomposition of Microcystis sp. Cell and Formation of Chlorination Disinfection By-Products

Formation of disinfection by-products (DBPs) including trihalomethans (THM), haloacetic acid (HAA) and haloacetonitriles (HAN) from chlorination of extracellular organic matter (EOM) and cells + intracellular organic matter (IOM) of Microcystis sp., a blue-green algae, during decomposed period was investigated. Microcystis sp. cells + IOM and EOM of Microcystis sp. exhibited a high potential for DBP formation. HAAFP (formation potential) was higher than THMFP during decomposed period. In the variations of HAAFP species during decomposed period, the ratio of di-HAAFP species was gradually decreased and the ratio of tri-HAAFP species was gradually increased in the case of EOM during decomposed period, while the opposite result was in the case of cells + IOM during decomposed period. In the variations of HANFP species during decomposed period, the ratio of di-HANFP species was much higher than the ratio of tri-HAAFP species.