• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
• /
• 1998.11a
• /
• pp.60-63
• /
• 1998

본 연구에서는 유류 오염토양 복원을 위한 효율적인 세척공정을 구성하여 현장적용 가능성을 검토하였다. 토양세척공정은 co-current식 전세척장치와 counter -current식 세척조로 구성된다. 물이 주입되는 co-current식 전세척장치에서는 스크류 축의 회전력에 의한 토양 이송 및 스크류의 각 pitch 사이에 부착된 임펠러의 기계적 교반력에 의한 세척이 동시에 이루어진다. 전세척장치를 통과한 토양과 물은 세척조로 유입되어 세척용액과 반대방향으로 이동하게 된다. 세척조의 내벽에 부착된 나선형 웨어에 의해 적정 운전조건하에서 일정 크기를 기준으로 토양이 분리되며, 각 웨어 사이에 부착된 임펠러의 교반력에 의해 오염토양이 세척된다. 실험결과, 운전시 고려해야 할 주요 영향인자들은 전세척장치에서의 토양주입량은 1 kg/min, 진탕비는 1, 회전속도는 50 rpm에서 최대 세척효율(#4-, 83.6%)을 보였으며, 세척조에서는 토양.물 주입위치 15 cm, 회전속도 5 rpm, 경사각 6$^{\circ}$, 세척용액 주입유량이 0.8 L/min일 때 최대 세척효율인 97.9%(#4-)를 나타냈다.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
• /
• 2003.09a
• /
• pp.318-321
• /
• 2003

비소로 오염된 토양, 하천 퇴적물 및 광미의 복원할 때, 토양 세척 공정에서 중요한 인자인 비소의 화학적 결합형태와 세척제에 따른 용출특성과 고효율 세척 및 세척액의 재활용도를 높이기 위한 공정을 바탕으로 토양세척장비를 설계하였다. 화학적 결합형태에 있어서 토양은 잔류 결합형태가 주되고, 퇴적물의 경우는 철산화물과의 결합형태가 강하며, 광미는 황화물과의 결합에 따른 잔류형태와 철산화물과의 결합형태가 상당부분을 차지한다. 세척제에 따른 용출특성으로부터, 철산화물과 황화물과 결합하고 있는 비소의 화학적 결합형태를 파괴하면서 비소를 추출할 수 있는 용제로 HCl, Oxalate, EDTA, M$_2$O$_2$를 사용하였다. 추출 결과, 비소가 철산화물과 결합한 형태가 비중이 높을수록 EDTA 나 Oxalate가 효율이 높으며, 황화물에 대해서는 HCl과 $H_2O$$_2$이 상대적으로 높은 추출 효율을 보였다. 구성된 세척조는 밀폐실린더형과 스크류이송형 세척조로 구성되어 각각 혼합교반에 의한 세척과 토양입자 분급에 따른 세척이 가능하다. 세척 공정중 최적 산도 조절이 중요한 인자가 되며, 세척액의 재활용도를 높일때, 세척수에 용해되어 있는 비소 및 중금속과 미립자의 동시 제거를 위한 응집 침전조에서 응집제에 의해서 미립자와 함께 제거하는 응집, 침전 및 분리공정을 배치하였다.

• Journal of Soil and Groundwater Environment
• /
• v.14 no.1
• /
• pp.61-67
• /
• 2009

A non-discharged system of sequentially physico-chemical water treatment was used to treat the contaminated water produced from washing system of soils according to full-scale soil washing. After washing the TPH contaminated soils, the remaining concentrations of COD$_{Mn}$, SS, and n-hexane were analyzed for each compartment to estimate the treatment efficiencies of non-discharged system. Three times of sampling events were conducted for 4 different compartments (sediment tank, flocculation tank, oil/water separator, and process-water tank). In addition, soil washing efficiencies and concentrations of each parameter (COD$_{Mn}$, SS, and n-hexane) for process-water tank were analyzed for about 8 months. As results, the average efficiency of soil washing was high to have 95.9%, regardless of the condition of TPH contamination level for soils, as well as the concentrations of COD$_{Mn}$, SS, and n-hexane in the process-water tank were below the regulation limits of the Water Environmental Conserveation Act. Accordingly, the full-scale washing treatment system in this study could make the washing water 100% recycled which lead the system to be environmentally-friendly and economical.

• Journal of Korea Soil Environment Society
• /
• v.3 no.3
• /
• pp.55-62
• /
• 1998

Soils contaminated with hydrocarbons and residual metals can be effectively treated by soil washing. In developing the soil washing process several major effects for separating contaminants from coarse soils progressively improved upon combinations of mining and chemical processing approaches. The pilot-scale soils washing process consists of the four major parts : 1) abrasive scouring, 2) scrubbing action using a washwater that is sometimes augmented by surfactants or other agents, 3) rinsing, and 4) regenerating the contaminated washwater. The plant was designed based upon the treatment capacity > 5 ton/hr on site. The lumpy contaminated soil fractions first experience deagglomeration and desliming passing through a rolling mill pipe. In the second unit the attrition scrubbing module equipped with paddles uses high-energy to remove contaminants from the soils. And a final rinsing system is assembled to separate the washwater containing the contaminants and very fine soils from the washed coarse soils. For recycling the contaminated washwater passes through a washwater clarifier specifically designed for flocculation, sedimentation and gravity separation of fine as well as flotation and separation of oils from the washwater. In order to more rapidly assess the applicability of soil washing at a potential site while minimizing the expense of mobilization and operation, a mobile-type soil washing process which is self-contained upon a trailer will be further developed.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
• /
• v.16 no.1
• /
• pp.41-47
• /
• 2018

Radioactive substances, especially $^{137}Cs$ discharged in the course of Nuclear Power Plant Accident or maintenance of power plants, cause contamination of the soil. For habitation of residents and reuse of industrial land, it is inevitably necessary to decontaminate the soil. This study examines a soil washing process that has actually been used for washing of radioactive-contaminated soil. The soil washing process uses a washing agent to weaken surface tension of the soil and cesium, separating cesium from the soil. In this study, in order to raise the efficiency of the process, a flocculating agent was added to the washing water to remove fine soil and cesium. The cesium concentrations before and after applying the flocculating agent to cesium solution were measured through ICP-OES. When using 0.1 g of J-AF flocculating agent in the experiment, the maximum Cs removal performance was approximately 88%; the minimum value was 67%. Species combinations between cesium and soil were predicted using Visual MINTEQ Code; the ability to reuse the washing water or not, and the removal rate of the fine soil, determined via measurement of the turbidity after applying the flocculating agent, were determined.

• Journal of Soil and Groundwater Environment
• /
• v.13 no.2
• /
• pp.70-75
• /
• 2008

This study was carried out to evaluate the applicability of the full scale soil washing processes for reducing heavy metal contamination level of soil around an abandoned mine. In the results of soil washing of the target soil with $H_2SO_4$ and NaOH, the As concentrations of treated soil continuously increased compared with contaminated raw soil. Also, removal efficiencies of Zn and Ni were low. This problems might be caused by chemical partitioning of As in soil and its geologic origination, soil particle size, and scale up of washing plant.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
• /
• 2005.04a
• /
• pp.264-267
• /
• 2005

플럭 형성 비소 오염토양에 대한 토양세척기법의 적용성 실험결과, 세척용액 100 mM과 500 mM의 농도에서 대상 토양에 대한 비소 용출량은 수산화나트륨이 염산보다 높은 효율을 보였으며, 농도 1000 mM의 경우에는 염산이 비교적 우세한 세척효율을 보였다. 토양오염공정시험법에 의한 세척후 토양내 잔류비소 농도의 경우, 염산이 수산화나트륨과 비슷하거나 다소 우세함을 알 수 있었다. 세척 대상 토양의 Cut-off size limit을 선정하여 토양세척시 생성되는 플럭을 제거하지 않고 반복 세척한 결과, 수산화나트륨의 농도 200 mM은 1000 mM에 비하여 잔류된 비소량이 비슷하거나 비교적 높았으며, 2가지 농도에 대하여 총 5회 반복 세척한 토양의 비소 농도는 토양환경보전법의 가지역 우려기준 농도인 6 mg/kg에 근접한 결과를 보였으나, 염산의 경우 총 5회 세척시 비소의 농도가 약 9 mg/kg으로 비소 잔류량이 보다 큼을 알 수 있었다. 플럭을 제거한 후 반복 세척시 수산화나트륨의 농도 1000 mM이 200 mM에 비하여 토양 세척효율이 증가하였으며, 1000 mM로 5회 세척시 잔류비소 농도가 가지역 우려기준 농도에 근접한 약 6.7 mg/kg이었고 염산을 이용하여 세척한 경우에는 3회 세척시 약 6.7 mg/kg 4, 5회 반복 세척시 각각 약 3.9, 3.3 mg/kg으로 가지역 우려기준에 적합한 농도조건이 됨을 알 수 있었다.

• Proceedings of the KSEEG Conference
• /
• 2002.04a
• /
• pp.86-88
• /
• 2002

• Journal of Korea Soil Environment Society
• /
• v.3 no.3
• /
• pp.109-116
• /
• 1998

Treatability tests of a soil washing device were performed for the remediation of eil-contaminated soil. The contaminant-containing soil with water was first fed into a oc-current screw conveyor and then into a counter-current washer. Surfactant was introduced into the washer and feeding soil was continuously separated on the basis of #40 mesh at the same time. A washing efficiency of 97.9% was achieved by the the soil washing device optimized.

• Journal of Soil and Groundwater Environment
• /
• v.13 no.1
• /
• pp.32-42
• /
• 2008

A surfactant recovery and reuse process by selective adsorption with activated carbon was proposed to reduce surfactant cost in a soil washing process. Mathematical model simulation was performed for the whole process, which consists of soil washing, soil recovery, and soil re-washing. The optimal range of surfactant dosage was $6{\sim}10$-fold critical micelle concentration in soil. The efficiency of surfactant reuse process was decreased with increasing the dosage of activated carbon. Effectiveness factor for activated carbon significantly altered the efficiency of the reuse process unlike effectiveness factor for soil. Total requirement of surfactant was reduced to 20-30% with the reuse process compared to the conventional soil washing process. The contamination of wastewater after soil washing was reduced with the reuse process. This mathematical model can be used to estimate performance of the whole process of soil washing including surfactant recovery and to obtain optimal ranges of operating conditions without extra labor-intensive experimental works.