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지중 토양교반과 토양세정의 연계를 통한 중금속 오염토양 정화
유종찬 ( Jong-chan Yoo ),곽송종 ( Song-jong Kwak ),이제신 ( Je-shin Lee ),전필용 ( Pil-yong Jeon ),박응렬 ( Eung-ryeol Park ),백기태 ( Ki-tae Baek ) 한국환경기술학회 2016 한국환경기술학회지 Vol.17 No.1
본 연구에서는 Cu, Pb으로 오염된 철도부지의 토양정화에 있어 지중처리의 효과를 극대화하기 위하여 지중 토양교반공정의 적용에 따른 토양 내 중금속의 추출 및 이동성을 증가시킴과 동시에 토양세정공정과 연계하여 효과적인 토양정화공정을 설계하고자 하였다. 토양교반공정은 실험실규모의 지중토양교반 장치를 제작하여 수돗물, 0.1 M HCl, EDTA을 사용하였으며, 토양과 교반제의 고액비는 실제 현장에서의 적용성을 고려하여 1:0.3 (wt/v%)으로 진행하였다. 토양교반제로 EDTA을 사용하였을 때, 토양 내 Fe 산화물과 결합된 Cu 및 Pb은 각각 약 35%, 28%의 대체로 낮은 추출효율을 보였다. 토양세정공정은 실험실규모의 컬럼실험을 통하여 진행하였으며, 토양세정액은 토양교반공정과 동일하게 수돗물, 0.1 M HCl, EDTA를 사용하여 총 약 85 bed volume을 1.5 mL/min의 속도로 세정액을 주입해 주었다. 그 결과, 토양교반공정의 유무와 상관없이 HCl을 사용한 토양세정 실험군에서 토양으로부터 세정제로 많은 양의 Cu 및 Pb이 추출되었으며, 국내 토양환경보전법 1지역 우려기준치를 만족하였다. 이는 비교적 긴 접촉시간에 따른 토양의 산성화로 인해 수소이온과 토양 내 중금속과의 이온교환에 의한 결과이다. 또한, 토양세정 후 컬럼 내 토양을 3등분하여 분석한 결과, 토양교반-토양세정공정에서 수돗물-EDTA을 사용하였을 때 토양 내 잔류하는 Cu 및 Pb의 농도는 각각 130, 160 mg/kg이었다. 이 결과를 바탕으로, 실제 중금속으로 오염된 부지를 대상으로 정화공정을 설계할 때, 지중토양교반을 적용하여 지중 토양을 슬러리상태로 만들어 투수성을 증대시킨 후 토양세정을 통해 토양으로부터 중금속을 효과적으로 제거할 수 있을 것으로 기대된다. In this study, soil remediation processes combined with soil mixing and soil flushing was investigated to treat field soil contaminated with Cu and Pb near railroad site. Tap water, HCl and EDTA (0.1 M) were used to apply in-situ soil mixing process at a 1:0.3 of solid and liquid ratio. EDTA extracted 35% and 28% of Cu and Pb bound to Fe/Mn oxides from soil, respectively. Soil flushing process was conducted in a glass column using tap water, 0.1 M of HCl and EDTA for 24 h at a flow rate of 1.5 mL/min. As a result, HCl could significantly extract Cu and Pb from soil regardless of soil mixing process, and the concentration of them in soil after soil flushing process could meet Korean soil quality levels. Cu and Pb could be extracted by ion-exchange with hydrogen ions and longer contact time with acids. Furthermore, tap water for soil mixing and EDTA for mixing-flushing process could significantly decrease the concentration of Cu and Pb. Based on these results, it can be expected to design an effective in-situ soil remediation process via application of soil flushing after increase of soil permeability by in-situ soil mixing process.
Cr(VI)으로 오염된 부지의 안정화 기술에 의한 정화 타당성 연구
윤근석,유종찬,고성환,심명호,조명현,백기태,Yoon, Geun Seok,Yoo, Jong Chan,Ko, Sung-Hwan,Shim, Myung-Ho,Cho, Myung-Hyun,Baek, Kitae 한국지하수토양환경학회 2017 지하수토양환경 Vol.22 No.4
In this study, a remedial investigation using reductive stabilization was conducted to treat Cr(VI)-contaminated soil. The influences of various operational parameters, including reaction time and the mass of ferrous iron, were also evaluated. The study site was contaminated with a large amount of Cr(III) and Cr(VI), and the selected treatment method was to stabilize Cr(VI) with ferrous iron, which reduced Cr(VI) to Cr(III) and stabilized the chromium, although a greater mass of ferrous iron than the stoichiometric amount was required to stabilize the Cr(VI). However, some Cr(III) re-oxidized to Cr(VI) during the drying process, and addition of a strong reducing agent was required to maintain reducing conditions. With this reducing agent, the treated soil met the required regulatory standard, and the mass of Cr(III) re-oxidized to Cr(VI) was significantly reduced, compared to the use of only Fe(II) as a reducing agent.
토양 세척법에 의한 유류오염 사질토양의 TPH 추출 효율 평가
이차돌,유종찬,양중석,공준,백기태,Lee, Cha-Dol,Yoo, Jong-Chan,Yang, Jung-Seok,Kong, Jun,Baek, Kitae 한국지하수토양환경학회 2013 지하수토양환경 Vol.18 No.7
The influences of various operating parameters on physico-chemical techniques were evaluated to remediate petroleum-contaminated sandy soil including S/L ratio, kinetic, and effect of soil particle size. The simple extraction using tap water removed only 20.6% of total petroleum hydrocarbon (TPH), and addition of NaOH enhanced the removal of TPH to approximately 30%. To meet the regulation levels, a surfactant, sodium dodecyl sulfate, was added, and the removal of TPH increased to 4 times. Probably, the carbonate minerals affected chemical aging and soprtion of petroleum, which inhibited the extraction of TPH. The soil with smaller particle size contained more TPH, and the removal of TPH was obstructed with smaller particle size. However, NaOH addition increased the removal of TPH in the smaller particles. The physico-chemical properties of soil influenced greatly the removal of petroleum even in sandy soil.
신연준,이차돌,유종찬,양중석,김호섭,백기태,Shin, Yeon-Jun,Lee, Cha-Dol,Yoo, Jong-Chan,Yan, Jung-Seok,Kim, Ho-Sub,Baek, Kitae 한국지하수토양환경학회 2015 지하수토양환경 Vol.20 No.1
In this study, the mechanisms on ultrasonication enhanced metals extraction were investigated compared with the conventional washing technique. We hypothesized the mechanisms on enhanced extraction of ultrasonication: ultrasonication increased the temperature of soil slurry and decreased average particle size of soil due to breakdown of soil aggregate. Actually, the ultrasonication increased the temperature of soil slurry to $60^{\circ}C$ in this study, and the increase in the temperature enhanced the metal extraction to 15-20% even in the conventional simple mixing. The conventional washing technique decreased average size of soil particles because of breakdown of soil aggregate, and the ultrasonication decreased the size more than that of washing. The breakdown of soil aggregate improved the contact between metals and washing agent, which enhanced the extraction of metals in the ultrasonication. Therefore, we concluded that the main mechanisms of ultrasonication are increase in the temperature and breakdown of the soil aggregate. Finally, the ultrasonicaiton increased the extractability of metals upto 40% compared to conventional washing technique.
김은정 ( Eun Jung Kim ),유종찬 ( Jong-chan Yoo ),박상민 ( Sang-min Park ),박응렬 ( Eung-ryel Park ),백기태 ( Ki Tae Baek ) 한국환경분석학회 2016 환경분석과 독성보건 Vol.19 No.1
Distribution of heavy metals in different particle size fraction of soil could affect the risk of human metal intake and the soil removal efficiencies. In this study, metal contaminations in soils and metal distributions in various soil particle sizes were investigated in the areas affected by the former Janghang smelter. Soil samples were collected from two rural areas (A, B) located over 3 km away from the former smelter and one area (C) located within 100 m from the smelter. Soils were partitioned into four particle size fractions (>2 mm, 2-0.075 mm, 0.075-0.038 mm, and <0.038 mm) and metal distributions in particle size fractions were characterized. Soils in site C was highly contaminated with arsenic and heavy metals due to the influence of the smelter, while metal concentrations in sites A and B were quite low compared to those in site C. The metal concentrations in site A were close to the background metal concentrations indicating that this site was not affected by the smelter. On the other hand, soils in site B showed high arsenic concentrations, which might be affected by the smelter and soil mineral characteristics in this site. Lead and copper were accumulated in the fine particles (<0.038 mm) mainly by sorption, while arsenic was enriched in sand fraction (0.075-2 mm) associated with soil minerals.
김경조 ( Kyung Jo Kim ),유종찬 ( Jong Chan Yoo ),양중석 ( Jung Seok Yang ),백기태 ( Ki Tae Baek ) 한국화학공학회 2013 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.51 No.6
Sediment contains a high fraction of organic matter, high buffering capacity, and a large portion of fine grained particles such as silt and clay, which are major barriers to remove heavy metals from sediments. In this study, a lab-scale electrokinetic (EK) technique was applied to remove heavy metals effectively from marine sediment at a constant voltage gradient of 2 V/cm. A concentration of 0.1 M of ethylenediaminetetraacetic acid (EDTA), citric acid (CA), HNO3, and HCl were circulated in the cathode, and tap water was circulated in the anode. CA extracted 92.4% of Ni, 96.1% of Cu, 97.1% of Zn, and 88.1% of Pb from marine sediment. A higher voltage gradient enhanced the transport of citrate and EDTA into the sediment and, therefore, increased metal extraction from the marine sediment through a complexation reaction between metals and the chelates. Based on these results, the electrokinetic process using a high voltage gradient with EDTA and CA might be useful to extract heavy metals from marine sediment.
유종찬,김재련 한국데이타베이스학회 1998 Journal of information technology applications & m Vol.4 No.2
관계형 데이터베이스의 성능을 향상시키는데 중요한 요소 중의 하나는 트랜잭션을 처리하기 위해 데이터를 디스크에서 주 기억장치로 옮기는데 필요한 디스크 액세스(access) 횟수이다. 본 연구는 관계형 데이터베이스에서 트랜잭션을 처리할 때, 릴레이션(relation)을 속성의 중복할당을 허용하여 분할하고, 디스크에 단편(fragment)으로 저장하므로써 필요한 단편만을 액세스하여 디스크의 액세스 횟수를 줄이는 방법을 연구 하였다. 본 연구에서는 속성의 중복할당을 허용하여 디스크의 액세스 횟수를 최소화시킬 수 있는 수직분할문제의 수리모형을 조회, 갱신트랜잭션을 모두 고려하여 0-1 정수계획법으로 개발하였다. 또한 모형에 대한 최적해법으로 분지한계법을 제안하였으며, 분지한계법으로 큰 문제를 푸는데는 많은 시간이 소요되므로 계산량을 줄일수 있는 초기처리방법과 비용계산방법을 제안 하였다. 속성의 중복을 허용하여 구한 해가 중복을 고려하지 않은 경우의 해보다 디스크 액세스횟수가 감소한 것으로 나타났으며, 갱신트랜잭션의 수가 증가함에 따라 중복되는 속성의 수가 감소하는 결과를 나타내었다.