폐광산 주변 중금속 오염 농경지 토양 복원을 위한 석회(CaO)와 석회암($CaCO_3$)의 안정화 효율 규명 Lime (CaO) and Limestone ($CaCO_3$) Treatment as the Stabilization Process for Contaminated Farmland Soil around Abandoned Mine, Korea원문보기
국내 폐광산 주변 중금속 오염 농경지 토양 복원을 위해 석회(CaO)와 분쇄한 석회암($CaCO_3$)을 안정화제로 이용한 토양 안정화 공법의 효율을 규명하는 배치 및 대형 칼럼실험을 실시하였다. 오염토양은 경북 군위군에 위치한 아연 폐광산 지역의 오염 농경지 토양을 이용하였으며, 안정화제의 함량은 오염토양 대비 0, 0.5, 2, 5%로 다양하게 적용함으로써, 안정화제에 의해 토양으로부터 용출되는 중금속 농도 변화를 시간에 따라 측정하여 안정화제의 중금속 저감 효율을 규명하였다. 배치실험 결과, 가루상의 석회나 석회암 0.5%를 토양과 혼합하여 안정화제로 사용한 경우, 오염토양으로부터 As, Cd, Pb, Zn의 중금속 용출 농도는 안정화제를 사용하지 않은 토양으로부터의 용출 농도를 기준으로 각각 70, 77, 94, 그리고 95% 감소하여 중금속 용출 저감 효과가 매우 높은 것으로 나타났다. 토양 객토법을 모사한 대형 칼럼실험 결과, 2% 입상 석회 첨가에 의해서 As, Cd, Zn의 토양 용출은 안정화제를 사용하지 않은 토양 용출 농도를 기준으로 각각 63, 97, 98% 감소하였다. 입상 석회암을 안정화제로 이용한 칼럼에서는 2% 석회암 첨가에 의해서 As 용출 농도는 135.6${\mu}g/L$에서 30.2 ${\mu}g/L$ 감소하여 약 46% 이상의 감소율을 나타내었으며, Cd와 Zn의 경우에는 97% 이상 감소하였다. 배치 및 칼럼실험 결과 석회암의 중금속 용출 저감 효율이 석회의 저감 효율과 매우 비슷한 것으로 나타나, 토양으로부터 중금속을 안정화시키는데 입상 석회와 석회암 모두 효과가 매우 좋은 것으로 나타났다. 토양 산성화 방지를 위해 토양개량제로 주로 사용하였던 석회의 과도한 토양 내 첨가가 토양의 급격한 pH 증가를 일으켜 농작물 재배에 악 영향을 주게 되는 한계를 극복하기 위하여, 본 배치 및 대형 칼럼실험을 통하여 토양 내 첨가에 의한 pH 증가가 거의 없으며 비용 측면에서도 석회보다 훨씬 저렴하지만 중금속 용출 저감 효과가 비슷한 석회암이 중금속 오염 농경지 토양 복원을 위한 새로운 안정화제로 유용하게 사용될 수 있음을 입증하였다.
국내 폐광산 주변 중금속 오염 농경지 토양 복원을 위해 석회(CaO)와 분쇄한 석회암($CaCO_3$)을 안정화제로 이용한 토양 안정화 공법의 효율을 규명하는 배치 및 대형 칼럼실험을 실시하였다. 오염토양은 경북 군위군에 위치한 아연 폐광산 지역의 오염 농경지 토양을 이용하였으며, 안정화제의 함량은 오염토양 대비 0, 0.5, 2, 5%로 다양하게 적용함으로써, 안정화제에 의해 토양으로부터 용출되는 중금속 농도 변화를 시간에 따라 측정하여 안정화제의 중금속 저감 효율을 규명하였다. 배치실험 결과, 가루상의 석회나 석회암 0.5%를 토양과 혼합하여 안정화제로 사용한 경우, 오염토양으로부터 As, Cd, Pb, Zn의 중금속 용출 농도는 안정화제를 사용하지 않은 토양으로부터의 용출 농도를 기준으로 각각 70, 77, 94, 그리고 95% 감소하여 중금속 용출 저감 효과가 매우 높은 것으로 나타났다. 토양 객토법을 모사한 대형 칼럼실험 결과, 2% 입상 석회 첨가에 의해서 As, Cd, Zn의 토양 용출은 안정화제를 사용하지 않은 토양 용출 농도를 기준으로 각각 63, 97, 98% 감소하였다. 입상 석회암을 안정화제로 이용한 칼럼에서는 2% 석회암 첨가에 의해서 As 용출 농도는 135.6${\mu}g/L$에서 30.2 ${\mu}g/L$ 감소하여 약 46% 이상의 감소율을 나타내었으며, Cd와 Zn의 경우에는 97% 이상 감소하였다. 배치 및 칼럼실험 결과 석회암의 중금속 용출 저감 효율이 석회의 저감 효율과 매우 비슷한 것으로 나타나, 토양으로부터 중금속을 안정화시키는데 입상 석회와 석회암 모두 효과가 매우 좋은 것으로 나타났다. 토양 산성화 방지를 위해 토양개량제로 주로 사용하였던 석회의 과도한 토양 내 첨가가 토양의 급격한 pH 증가를 일으켜 농작물 재배에 악 영향을 주게 되는 한계를 극복하기 위하여, 본 배치 및 대형 칼럼실험을 통하여 토양 내 첨가에 의한 pH 증가가 거의 없으며 비용 측면에서도 석회보다 훨씬 저렴하지만 중금속 용출 저감 효과가 비슷한 석회암이 중금속 오염 농경지 토양 복원을 위한 새로운 안정화제로 유용하게 사용될 수 있음을 입증하였다.
The mixing treatment process using lime (CaO) and limestone ($CaCO_3$) as the immobilization amendments was applied for heavy metal contaminated filmland soils around Goro abandoned Zn-mine, Korea in the batch and pilot scale continuous column experiments. For the batch experiments, with ...
The mixing treatment process using lime (CaO) and limestone ($CaCO_3$) as the immobilization amendments was applied for heavy metal contaminated filmland soils around Goro abandoned Zn-mine, Korea in the batch and pilot scale continuous column experiments. For the batch experiments, with the addition of 0.5 wt.% commercialized lime or limestone, leaching concentrations of As, Cd, Pb, and Zn from the contaminated filmland soil decreased by 70, 77, 94, and 95 %, respectively, compared to those without amendments. For the continuous pilot scale column experiments, the acryl column (30 cm in length and 20 cm in diameter) was designed and granulated lime and limestone were used. From the results of column experiments, with only 2 wt.% of granulated lime, As, Cd, and Zn leaching concentrations decreased by 63%, 97%, and 98%, respectively. With 2 wt.% of granulated limestone, As leaching concentration reduced from 135.6 to 30.2 ${\mu}g/L$ within 5 months and maintained mostly below 10 ${\mu}g/L$, representing that more than 46% diminution of leaching concentration compared to that without the amendment mixing. For Cd and Zn, their leaching concentrations with only 2 wt.% of limestone mixing decreased by 97%, respectively compared to that without amendment mixing, suggesting that the capability of limestone to immobilize heavy metals in the filmland soil was outstanding and similar to that of lime. From the column experiments, it was investigated that if the efficiency of limestone to immobilize heavy metals from the soil was similar to that of lime, the limestone could be more available to immobilize heavy metals from the soil than lime because of low pH increase and thus less harmful side effect.
The mixing treatment process using lime (CaO) and limestone ($CaCO_3$) as the immobilization amendments was applied for heavy metal contaminated filmland soils around Goro abandoned Zn-mine, Korea in the batch and pilot scale continuous column experiments. For the batch experiments, with the addition of 0.5 wt.% commercialized lime or limestone, leaching concentrations of As, Cd, Pb, and Zn from the contaminated filmland soil decreased by 70, 77, 94, and 95 %, respectively, compared to those without amendments. For the continuous pilot scale column experiments, the acryl column (30 cm in length and 20 cm in diameter) was designed and granulated lime and limestone were used. From the results of column experiments, with only 2 wt.% of granulated lime, As, Cd, and Zn leaching concentrations decreased by 63%, 97%, and 98%, respectively. With 2 wt.% of granulated limestone, As leaching concentration reduced from 135.6 to 30.2 ${\mu}g/L$ within 5 months and maintained mostly below 10 ${\mu}g/L$, representing that more than 46% diminution of leaching concentration compared to that without the amendment mixing. For Cd and Zn, their leaching concentrations with only 2 wt.% of limestone mixing decreased by 97%, respectively compared to that without amendment mixing, suggesting that the capability of limestone to immobilize heavy metals in the filmland soil was outstanding and similar to that of lime. From the column experiments, it was investigated that if the efficiency of limestone to immobilize heavy metals from the soil was similar to that of lime, the limestone could be more available to immobilize heavy metals from the soil than lime because of low pH increase and thus less harmful side effect.
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문제 정의
The research for the efficiency of limestone to immobilize heavy metals from soil in the stabilization process is very limited. The main objective of this research is to investigate the efficiency of "mixing soil treat- menf, using limestone as well as lime to immobilize heavy metal from the contaminated soil by lab scale experiments.
This research focused on the soil stabilization process by using not only lime but also limestone (CaCO3) to decrease the leaching of arsenic and other heavy metals from contaminated farmland soils around an abandoned mine, Korea. Batch experiments were performed to investigate the efficiency of lime and limestone as immobilizing amendments to reduce the heavy metal leaching from the contaminated soil.
제안 방법
The principal component analysis of B type lime and limestone was performed by X-ray fluorescence spectrometer (Shimadzu, XRF-1700) and the result is shown in Table 2. Because amount of the amendment affects the immobilization efficiency of heavy metals in soil, various amounts of amendments were used in the experiments (0, 0.5, 2, and 5 wt.% of soil mass). Powdered lime and limestone were used in batch experiments and granulated lime and limestone (4-6 mm in diameter) were used in column experiments.
For each batch experiment, the leaching concentration for each specific heavy metal from the contaminated farmland soil was measured on the conditions of diverse amounts of amendments. By using A and B type limestone as amendments, the batch experiments were repeated to investigate the efficiency of limestone on the immobility of heavy metals from the soil and their results were compared with those of lime. For the reliability of experimental data, the arithmetic mean of three batch experiments was accepted as the representative results.
Grain size distribution of soils was also measured through the dry-sieving and pipetting method. For the reliability of experimental data, the measurement of pH, TOC, and grain size analysis were repeated for three soil samples, and their arithmetic mean were determined as the final values of the soil. If any of them was over 5% of their arithmetic mean, the results were ignored and the experiment was duplicated.
The pH of discharged water was measured and its heavy metal leaching concentrations were analyzed on ICP/OES. From the column experiments, the accumulative mass of each heavy metal leached from the soil for 5 year was calculated to investigate the efficiency of lime and limestone on the immobiHzation of heavy metals. Fig.
Soil samples were dried in oven at 30℃ for 2-4 day and sieved at 2 mm in diameter. Physical and chemical properties of soil samples such as pH, TOC (total organic carbon content), and grain size, which directly affect leaching properties of heavy metals from soils, were measured. TOC was measured using a CHN (carbon, hydrogen, nitrogen) analyzer (Thermo Finnigan Flash EA 1112), and pH of contaminated soil was measured by electrode (Istek, 815PDC) via a distilled water extraction method (soikdistilled water =1:5).
대상 데이터
Most of mine tailings were washed away during the flood seasons and contaminated farmland and the stream connected with the mine. Eighty kilograms of surface soils were collected at the farmland, which was 500 m down away from the tailing storage site of the Goro mine. Soil samples were dried in oven at 30℃ for 2-4 day and sieved at 2 mm in diameter.
Heavy metal contaminated soils were sampled at the farmland (a rice paddy field) beside of the main stream connected to Goro abandoned Znmine, which is located at Gunwi county, Korea. Goro abandoned mine had been activated from 1950 to 1980 and about 30,000 tons of mine tailings and waste rock fragments had been left at the storage site, which was 200m down away from the mine entrance (Lee et al.
이론/모형
TOC was measured using a CHN (carbon, hydrogen, nitrogen) analyzer (Thermo Finnigan Flash EA 1112), and pH of contaminated soil was measured by electrode (Istek, 815PDC) via a distilled water extraction method (soikdistilled water =1:5). Grain size distribution of soils was also measured through the dry-sieving and pipetting method. For the reliability of experimental data, the measurement of pH, TOC, and grain size analysis were repeated for three soil samples, and their arithmetic mean were determined as the final values of the soil.
성능/효과
With 2 wt.% of granulated limestone mixing, Zn leaching concentration decreased to less than 10 μg/L leaching in the column, and the average Zn leaching concentration for 5 year decreased by 97% (arithmetic mean: 21.4 |ig/L) compared to that without the amendment mixing (Fig. 5(c)).
2(c) and (d)). From the results of the batch experiments, leaching concentrations of all heavy metals could be decreased much lower than KDWL by only the addition of 0.5% lime. There existed no big difference in the leaching concentration dethat B type lime, which is much cheaper than A type lime, could be used in the real contaminated sites
From the results of the continuous pilot scale column experiments, with only 2% of granulated lime, As, Cd, and Zn leaching concentrations decreased by 63%, 97%, and 98%, respectively, compared to that without the amendment mixing and they maintained much below KDWL for 5 year leaching. Even the pH of leaching water increased according to the lime addition, most of As were remained in soil during the "mixing treatment", suggesting that some of As were dissolved at highpH condition at first but they were immediately reprecipitated as fonns such as calcium carbonate and/or clay-organic complexes
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