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Effects of pH, dissolved organic matter, and salinity on ibuprofen sorption on sediment
Oh, Sanghwa,Shin, Won Sik,Kim, Hong Tae Springer Berlin Heidelberg 2016 Environmental Science and Pollution Research Vol.23 No.22
<P>Ibuprofen is well known as one of the most frequently detected pharmaceuticals and personal care products (PPCPs) in rivers. However, sorption of ibuprofen onto sediment has not been considered in spite of its high <I>K</I><SUB>ow</SUB> (3.5). In this study, the effects of various environmental conditions such as pH (4, 5.3, and 7), the concentrations of dissolved organic matters (0 to 1.0 mM citrate and urea), salinity (0, 10, 20, and 30 part per thousand), and presence of other PPCP (salicylic acid) on ibuprofen sorption were investigated. Linear model mainly fitted the experimental data for analysis. The distribution coefficient (<I>K</I><SUB>d</SUB>) in the linear model decreased from 6.76 at pH 4 to near zero at pH 7, indicating that neutral form of ibuprofen at pH below p<I>K</I>a (5.2) was easily sorbed onto the sediment whereas the sorption of anionic form at pH over p<I>K</I>a was not favorable. To investigate the effect of dissolved organic matters (DOMs) on ibuprofen sorption, citrate and urea were used as DOMs. As citrate concentration increased, the <I>K</I><SUB>d</SUB> value decreased but urea did not interrupt the ibuprofen sorption. Citrate has three carboxyl functional groups which can attach easily ibuprofen and hinder its sorption onto sediment. Salinity also affected ibuprofen sorption due to decrease of the solubility of ibuprofen as salinity increased. In competitive sorption experiment, the addition of salicylic acid also led to enhance ibuprofen sorption. Conclusively, ibuprofen can be more easily sorbed onto the acidified sediments of river downstream, especially estuaries or near-shore environment with low DOM concentration.</P>
실리콘 튜빙 담지 폴리우레탄 생물벽체를 이용한 지하수내 질산성 질소 제거
오상화 ( Sanghwa Oh ),신원식 ( Won Sik Shin ) 한국수처리학회(구 한국수처리기술연구회) 2018 한국수처리학회지 Vol.26 No.1
A column reactor with biobarrier consisting of polyurethane-activated carbon (PU-AC) media with hollow silicon tubing coiled inside the media was operated to estimate the potential for treatment of nitrate-contaminated groundwater. The tubing was also evaluated for its potential to provide carbon sources such as glucose, methanol, ethanol, and acetic acid for denitrification process. Methanol was selected as the most effective carbon because the highest amount of methanol could be delivered with appropriate releasing rate. In a column experiment, the groundwater containing 60 mg/L of nitrate was flowed through the PU-AC biobarrier. Denitrification of NO<sub>3</sub> <sup>-</sup> coupled to carbon supply throughout the silicon tubing was successfully observed, depending on the groundwater velocity and methanol concentration. For satisfying potable groundwater criteria of nitrate (10 mg/L), 0.033 cm/min of groundwater velocity with 3% of methanol content in silicon tubing was appropriate corresponding to negative ORP value of -240 mV during denitrification. To deduce the optimum operating condition of the column reactor, the groundwater velocity was further reduced to 0.018 cm/min and the carbon content (%) was changed from 2.0 to 3.5% in the silicon tubing, which resulting in 3.5% of the optimum value (approximately 83% of NO<sub>3</sub>-N removal). At this point, the ORP showed all negative values, indicating that ORP can be used as an indicator of denitrification in biobarrier in field.
오상화 ( Sanghwa Oh ) 한국수처리학회(구 한국수처리기술연구회) 2018 한국수처리학회지 Vol.26 No.4
The isotherm sorption and sequential desorption of ibuprofen were investigated using wetland sediment with several conditions such as pH 3, 3% of salinity, and 1 M Na-citrate as a dissolved organic matter (DOM), and salinity on sorption and desorption of ibuprofen in water/sediment system. Two sorption models such as linear and Freundlich models and two desorption resistance models such as bi-phasic desorption model and its modified model were used to fit the experimental data. The linear and Freundlich models fitted well to the sorption data (R<sup>2</sup>>0.99) and the bi-phasic desorption model (BPDM) and the modified bi-phasic desorption model (MBPDM) also fitted well to the desorption data (R2>0.98). For sorption, KF in Freundlich model was estimated in order of 9.1 (3% salinity) > 7.4 (pH 3) > 4.8 (Na-citrate) in accordance to Kp in linear model. For desorption, both BPDM and MBPDM fitted well the sequential desorption experiments. The final desorption resistance were also positively affected by salinity but negatively influenced by the presence of Na-citrate as DOM.
담체 충진여부에 따른 회분식 반응기내 혐기성 암모니아 산화 미생물의 질소제거 경향
오상화 ( Sanghwa Oh ) 한국수처리학회 2016 한국수처리학회지 Vol.24 No.2
Anaerobic ammonium oxidation (anammox) coupled to nitrite or nitrate reduction is very slow reaction with about 20days of doubling time. For cultivation of the very slow growing bacteria, a sequencing batch reactor (SBR) is considered the most credible reactor and the utilization of media for providing a high biomass concentration using a vast surface area. This study compared the N removal efficiencies of SBR with fluidized media to those without media. The optimum operating time in SBR with and without media, when the removal efficiency of TN did not increase anymore, appeared at 21 h and 24h, respectively. The TN removal efficiency was 61% and 35% in SBR with and without packed media at 24 h. It is because NO_{3}^{-} and NH₃ in SBR with media were more removed and NO_{3}^{-} was less produced than those without media by anammox and denitrification bacteria.
연속흐름식 반응조에서의 탈질소화와 혐기성 암모니아 산화 반응에 의한 질산성 질소 제거에 대한 유기물 주입 영향
오상화 ( Sanghwa Oh ) 한국수처리학회 2016 한국수처리학회지 Vol.24 No.5
In wastewater treatment plant, most of oxidized nitrogen is nitrate in aerobic and anoxic reactors. In this study, for this reason, we investigated the removal of nitrogen compounds via anaerobic ammonium oxidation (anammox) and denitrification by cell decay or external organics using a continuous flow reactor. The experiments consisted of three cases such as only media packed (case 1), only organic supplied (case 2) and both media packed and organic supplied (case 3). The mass balances for each case were conducted to analyze the nitrogen removal mechanism. FISH(fluorescence in situ hybridization) and image analysis technique was also used to calculate the content of anammox bacteria and nitrifying bacteria for each case. Conclusively, the organic supply made anammox reaction decreased and denitrification activated. Media supply was helpful to activate anammox. FISH analysis also presented that the content of anammox bacteria such as Brocadia Anammoxidans and Kuenenia Stuttgartiansis was increased when media was supplied.
Na<sub>2</sub>S를 이용한 EDTA 토양세척수로부터의 중금속 분리
오상화,신원식,Oh, Sanghwa,Shin, Won Sik 한국지하수토양환경학회 2015 지하수토양환경 Vol.20 No.7
Soil washing with ethylenediaminetetraacetic acid (EDTA) is highly effective in the remediation of soils contaminated with heavy metals. The EDTA recycling process is a requisite for reducing the operating cost. The applicability of Na<sub>2</sub>S addition on the precipitation of heavy metals from the spent soil washing solution and thereby recycling of EDTA was investigated. Addition of Na<sub>2</sub>S into the single metal-EDTA and the mixed metal-EDTA solutions ([Na<sub>2</sub>S]/[metal-EDTA] ratio = 30, reaction time = 30 min and pH = 7~9) was highly effective in the separation of Cu and Pb from metal-EDTA complexes, but not for Ni. The Zn removal efficiency varied with pH and slightly increased upto 40% as the reaction time increased from 0 to 240 min which was longer than those for Cu and Pb. Ca(OH)<sub>2</sub> was subsequently added to induce further precipitation of Zn and Ni and to reduce the Na<sub>2</sub>S dose. At the [Na<sub>2</sub>S]/[metal-EDTA] ratio of 10, the removal efficiencies of all heavy metals excluding Ni were above 98% with the dose of Ca(OH)<sub>2</sub> at 0.002, 0.006 and 0.008 g into 100 mL of Cu-, Pb- and Zn-EDTA solutions, respectively. However, Ca(OH)<sub>2</sub> addition was not effective for Ni-EDTA solution. A further research is needed to improve metal removal efficiency and subsequent EDTA recycling for the real application in field-contaminated soils.
협력적 필터링과 콘텐츠 정보를 결합한 영화 추천 알고리즘
김상화(Sanghwa Kim),오병화(Byonghwa Oh),김문종(Moonjong Kim),양지훈(Jihoon Yang) 한국정보과학회 2011 한국정보과학회 학술발표논문집 Vol.38 No.2B
추천 시스템은 사용자의 관심을 고려하여 새로운 추천 아이템을 예측한다. 대부분의 추천 시스템은 협력적 필터링 또는 콘텐츠 기반의 방법을 사용한다. 두 방법은 각자의 장점을 가지고 있지만 상황에 따라 알맞은 추천 결과를 내지 못하기도 한다. 두 방법의 이점들을 통합한 하이브리드 추천 시스템은 각 방법들의 단점을 극복할 수 있다. 본 논문에서는 콘텐츠 기반의 방법과 협력적 필터링을 효과적으로 통합할 수 있는 구조를 소개한다. 제안한 방법은 하나의 기법만 이용한 모델에 비해 높은 성능을 보여주었다.