• 방사성폐기물학회지
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• 제22권2호
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• pp.159-171
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• 2024

This study aimed to develop an efficient recycling process for wastewater generated from soil-washing used to remediate uranium (U(VI))-contaminated soil. Under acidic conditions, U(VI) ions leached from the soil were precipitated and separated through neutralization using hydrazine (N₂H₄). N₂H₄, employed as a pH adjuster, was decomposed into nitrogen gas (N₂), water (H₂O), and hydrogen ions (H⁺) by hydrogen peroxide (H₂O₂). The residual N₂H₄ was precipitated when the pH was adjusted using sulfuric acid (H₂SO₄) to recycle the wastewater in the soil-washing process. This purified wastewater was reused in the soil-washing process for a total of ten cycles. The results confirmed that the soil-washing performance for U(VI)-contaminated soil was maintained when using recycled wastewater. All in all, this study proposes an efficient recycling process for wastewater generated during the remediation of U(VI)-contaminated soil.

• 한국환경과학회지
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• 제17권2호
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• pp.185-193
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• 2008

This study has been carried out to examine the feasibility of soil washing process for reducing arsenic contamination level of soil around $Dalch\hat{e}n$ Mine. The results of physicochemical tests of the target soil showed that pH was weak alkalic ($pH{\simeq}7.8$), soil texture was coarse sand, and organic contents (5.7%) and CEC (Cation exchange capacity; 21.5 meq/100 g) were similar with those of soils generally found in Korea. Contamination levels of arsenic were found to over 201 mg/kg which exceed the Korea standard levels of countermeasure and concern. To investigate chemical partitioning of heavy metals, sequential extraction procedures were adopted and it was found that arsenic was predominantly associated with the residual fraction among five fractional forms as much as over 85%, which is demonstrating that only less than 15% of all might be vulnerable to a selected washing agents. Among 6 kinds of washing agents applied on the screening for arsenic-contaminated soil, HCl and $H_3PO_4$ solution were selected as promising washing agents. In comparison with HCl and $H_3PO_4$ solutions for arsenic washing by kinetic experiment in the change of pH, soil-solution ratio, temperature, and washing solution concentration, $H_3PO_4$ solution was determined to best one of agents tested, which showed faster washing rate than HCl to accomplish regulatory goal.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2003년도 추계학술발표회
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• pp.148-151
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• 2003

Soil washing was applied as a supplementary step of soil remediation at a petroleum oil contaminated site. A soil washing system was designed, assembled, and operated at the site. A field screening method with PetroFlagTM was adopted at the site to find the exact boundary of contaminated area as soil excavation progressed and to verify the concentration of treated soil. The system operation showed the cleanup efficiency of 90% at the compatible cost compared to other methods.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 1999년도 추계학술발표회
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• pp.95-98
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• 1999

The goal of present study is to evaluate the potential of soil washing for removing metal contaminants from a contaminated soil. Remediation of a soil contaminated with copper, cadmium and phenol were performed by a soil washing using a biosurfactant. The removal of copper, cadmium and phenol from soil (sandy, kaoline, mixed one) was evaluated as a function of biosurfactant (wt %) concentration in the batch process. The results showed that overall rejection coefficient for copper, cadmium and phenol were grater than 50 %, 25 %, respectively.

• 한국물환경학회지
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• 제22권5호
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• pp.871-878
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• 2006

Batch experiments were performed to evaluate the applicability of soil washing for heavy metal contaminated soils at Nacdong and Hamchang abandoned mines. The texture of the Nacdong soil was sandy loam. Nacdong abandoned mine soil was almost neutral (pH=6.5). Contaminations of As, Cd, Pb and Zn for Nacdong mine soils were 12,900 mg/kg, 29 mg/kg, 696 mg/kg and 276 mg/kg, respectively. Hamchang abandoned mine soils were acidic (pH=2.6) and the soil texture was loam. The contaminations of As, Cd, Pb and Zn for Hamchang abandoned mine soils were 6,410 mg/kg, 291 mg/kg, 1,300 mg/kg and 1,110 mg/kg, respectively. For the Nacdong abandoned mine soils, oxalic acid was found to be the most effective soil washing extracter for As and Pb while citric acid was the most effective extracter for Cd. For the Hamchang abandoned mine soils, oxalic acid showed the highest extraction efficiencies for As and Pb, whilst citric acid presented the best soil washing efficiencie for Cd. Oxalic acid and EDTA were found to be the most effective soil washing extracter for the Hamchang abandoned mine contaminated soils.

• 한국지하수토양환경학회지:지하수토양환경
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• 제20권1호
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• pp.28-35
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• 2015

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.

• 한국지하수토양환경학회지:지하수토양환경
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• 제12권3호
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• pp.17-22
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• 2007

납으로 오염된 실제 토양을 처리하기 위해 토양세척기술의 적용성을 평가하였다. 세척제로는 염산을 사용하였으며, 0.2 M 염산을 사용하여 고액비 1:3으로 하여 10분간 접촉하여 2회 세척하여준 결과 96%의 제거율을 보였다. 세척액과 토양의 접촉시간을 5분에서 120분까지 증가하였을 때, 제거효율은 69.3%에서 81.9%로 증가하였다. 입경별 토양세척 효율은 온도와 교반시간에 영향을 받았으며, 20분 이상 교반하여 준다면, 0.075 mm 이하, 0.075 mm-2.0 mm, 2.0-4.0 mm 의 입경별 토양에서는 모두 99%의 제거효율을 보였다. 이상의 결과는 본 연구에 사용된 납 오염 토양은 토양세척기술을 적용하여 효과적으로 처리할 수 있는 것을 의미한다.

• 한국의류산업학회지
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• 제9권6호
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• pp.671-678
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• 2007

Formulations of compact and supercompact heavy-duty detergents, which are being used widely around the world, differ from those of conventional heavy-duty detergents. Significant differences in composition exist between the compact detergents and the conventional detergents. The compact detergents have a higher content of surfactants, oxygen bleach and enzymes than the conventional detergents. We have studied to find the most effective washing conditions of artificially soiled cloths with a commercial, supercompact, heavy-duty detergent and a drum type washing machine which is becoming the preferred type in Korea. Moreover, we have studied the washing performance with an impeller type washing machine, which has heretofore been the most popular type in East Asia. With the drum-type washing machine, washing performances improved as the washing temperatures went up and the washing times were lengthened. Though the rate of soil removal with a double recommended dosage was higher than with the recommended amount at $20^{\circ}C$, the effects of the higher dosage decreased as the washing temperatures increased. Finally, the washing performances with the two different dosages were the same at $60^{\circ}C$. The washing performances at $40^{\circ}C$ with the recommended dosage for 90 minutes were the same as with the double recommended dosage for 45 minutes. The soil removal efficiencies with the impeller-type washing machine were much lower than those of the drum-type washing machine. The reasons for this were the higher bath ratio that led to the lower concentration of wash liquor, the shorter washing time, and the lower washing temperature.

• 자원환경지질
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• 제52권1호
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• pp.1-12
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• 2019

금속 폐기물과 TPH(total petroleum hydrocarbon: 석유계 총탄화수소)로 복합 오염된 토양을 정화하기 위하여 자력선별법을 연계한 토양세척 배치실험을 실시하였다. 오염토양의 아연과 TPH 농도는 각각 1743.3 mg/kg과 3558.9 mg/kg으로 심하게 오염되어 있었으며, 아연, 납, 구리, TPH 항목들이 '2지역 토양오염우려기준'(정화목표)을 초과하였다. 중금속 제거를 위해 1차 산세척을 실시하였으나 납과 아연은 산세척 후에도 '2지역 토양오염우려기준'을 초과하였으며, 2차 연속 세척에 의해서 아연과 납의 제거효율은 각각 8 %와 5 % 증가에 그쳐, 정화목표에 도달하지 못하였다. 오염토양의 중금속 초기농도를 줄이고 세척 효과를 높이기 위하여 세척 전 미세입자(직경 < 0.075 mm)를 선별하였으며, 오염토양의 4.1 %가 분리되었다. 미세입자 선별만으로 오염토양의 초기 아연과 납 농도는 1256. 3 mg/kg(27.9 % 감소)과 325.8 mg/kg(56.3 % 감소)으로 감소하였으나, 미세입자 선별 후 오염토양을 1차 세척한 결과 아연 농도가 '2지역 토양오염우려기준'보다 높게 나타나, 이를 만족시킬 수 있는 추가 제거방법이 필요하였다. 본 토양이 무분별한 금속폐기물 투기에 의해 오염되었다는 사실로부터, 미세입자 선별의 대안으로 자력선별법을 적용하였으며, 토양의 16.4 %가 자력선별에 의해 제거되었다. 자력선별 후 오염토양의 아연과 납 농도는 637.2 mg/kg (63.4 % 감소)과 139.6 mg/kg (81.5 % 감소)로 감소하여, 1회 토양세척과 미세입자 선별에 의한 중금속 제거 효과보다 높았다. 자력선별 후 오염토양을 산용액으로 1차 세척한 결과, 오염토양 내 모든 중금속과 TPH농도가 '2지역 토양오염우려기준'이하로 낮게 유지되어, 본 오염토양과 같이 금속폐기물을 많이 함유하고 있는 토양의 경우 자력선별법을 연계한 토양세척에 의해 중금속과 TPH를 동시에 효과적으로 제거할 수 있는 것으로 나타났다.

• 한국토양환경학회지
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• 제3권3호
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• pp.109-116
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• 1998

본 연구에서는 유류 오염토양 복원을 위한 효율적인 세척 공정과 장비를 구성하여 현장 적용 가능성을 검토하였다 토양세척 장비는 co-current식 전세척장치와 counter-current식 세척조로 구성된다. 토양 이송 및 부분 세척이 이루어지는 전세척장치를 통과한 토양과 물은 세척용액이 첨가되는 세척조로 유입되며, 적정 운전 조건하에서 내벽에 부착된 나선형 웨어에 의해 일정 입경을 기준으로 토양이 분리되며, 동시에 각 웨어 사이에 부착된 임펠러의 교반력에 의해 토양내 오염물질이 탈착된다. 실험 결과, 전세척장치는 토양주입량 1 kg/min, 진탕비 1, 회전속도 50 rpm에서 최대 세척효율 83.6%(#4-)을 보였으며 세척조에서는 토양.물 주입위치 15 cm, 회전속도 5 rpm, 경사각 $6^{\circ}$, 세척용액 주입유량 0.8 L/min일 때 최대 세척효율인 97.9% (#4-)를 나타내었다.