• 산업기술연구
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• 제30권A호
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• pp.37-43
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• 2010

Polymeric materials in addition to Portland cement and hydrated limes were used to solidify heavy metal contaminated tailings from five abandoned metal mines in Korea. Mine tailings were mixed separately with Portland cement and hydrated lime at a concentration of 20-30 wt% and 6-9 wt%, respectively and Ethylene Vinyl Acetate(EVA) powder was added to each specimen at a ratio of 2.5 and 5.0 wt% to binders. Polymer-added and polymer-free solidified forms were evaluated for their appropriateness in accordance with the suggested test methods. Regardless of addition of polymeric materials, all solidified forms satisfy the uniaxial compressive strength(UCS) requirements(0.35MPa) for land reclamation and show remarkably reduced leaching concentrations of heavy metals such as As, Cd, Cu, Pb and Zn less than the toxicity criteria of Korean standard leaching test(KSLT). The addition of polymeric materials increased the UCS of solidified forms to improve a long-term stability of solidified mine tailings.

• Membrane and Water Treatment
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• 제11권4호
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• pp.283-294
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• 2020

This work aims at studying the feasibility of continuous removal of mixed heavy metal ions from simulated zinc plating wastewaters by coupling a microbial fuel cell and a microbial electrolysis cell in batch and continuous modes. The discharging voltage of MFC increased initially from 0.4621 ± 0.0005 V to 0.4864 ± 0.0006 V as the initial concentration of Cr⁶⁺ increased from 10 ppm to 60 ppm. Almost complete removal of Cr⁶⁺ and low removal of Cu²⁺ occurred in MFC of the MFC-MEC-coupled system after 8 hours under the batch mode; removal efficiencies (REs) of Cr⁶⁺ and Cu²⁺ were 99.76% and 30.49%. After the same reaction time, REs of nickel and zinc ions were 55.15% and 76.21% in its MEC. Cu²⁺, Ni²⁺, and Zn²⁺ removal efficiencies of 54.98%, 30.63%, 55.04%, and 75.35% were achieved in the effluent within optimum HRT of 2 hours under the continuous mode. The incomplete removal of Cu²⁺, Ni²⁺ and Zn²⁺ ions in the effluent was due to the fact that the Cr⁶⁺ was almost completely consumed at the end of MFC reaction. After HRT of 12 hours, at the different sampling locations, Cr⁶⁺ and Cu²⁺ removal efficiencies in the cathodic chamber of MFC were 89.95% and 34.69%, respectively. 94.58%, 33.95%, 56.57%, and 75.76% were achieved for Cr⁶⁺, Cu²⁺, Ni²⁺ and Zn²⁺ in the cathodic chamber of MEC. It can be concluded that those metal ions can be removed completely by repeatedly passing high concentration of Cr⁶⁺ through the cathode chamber of MFC of the MFC-MEC-coupled system.

• Journal of Microbiology and Biotechnology
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• 제9권5호
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• pp.650-654
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• 1999

Undaria pinnatifida oxidized by nitric acid had a high capacity of Cu/sup 2+/ uptake (3.5 mmol Cu/sup 2+/g dry mass) at pH 4 and showed high affinity to Cu/sup 2+/ and Pb/sup 2+/, in a mixed-metal system, compared to Ca/sup 2+/ and Mg/sup 2+/. The IR spectrum showed increase of carboxylic acid on the surface of Undaria pinnatifida, mostly due to the effect of the oxidation reaction.

• 한국해양학회지:바다
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• 제4권3호
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• pp.198-207
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• 1999

시화호 내 5개 정점에서 채취한 주상시료들을 지화학적으로 분석하여 시화방조제 건설이후 퇴적환경 및 중금속오염에 대해 연구하였다. 시화호내 퇴적환경은 유기물의 C/N비와 C/S비에 의해 무산소환경, 산화환경, 그리고 두 환경이 공존하는 지역으로 세분되었다. 산화환원환경을 지배하는 요인은 수심과 퇴적물의 공급차인것으로 사료된다. 주상시료에서 분석된 지화학적 원소중 Mn-U-Mo간의 상관관계는 각 정점간의 산화 환원환경의 지시자로 사용이 가능하다. 주상시료들의 Al과 Ti 함량은 퇴적물특성에 의해 구분되며, 5개 중금속(Cr, Ni, Cu, Zn 및 Pb)함량은 중금속에 의한 오염정도를 지시한다. 중금속의 상대적 함량은 방조제에 가까운 시화호 중심부분에서 보다 안산-반월공단에 가까운 지역에서 높게 축적되어 있다. 특히 주상시료의 표층퇴적물은 시화호 중앙부보다 시화-반월공단쪽이 약 2-8배 정도로 중금속축적이 높다.

• Nuclear Engineering and Technology
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• 제55권8호
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• pp.2889-2896
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• 2023

The waste acceptance criteria for heavy metals in mixed waste should be developed by reflecting the leaching behaviors that could highly depend on the repository design and environment surrounding the waste. The current standards widely used to evaluate the leaching characteristics of heavy metals would not be appropriate for the silo-type repository since they are developed for landfills, which are more common than a silo-type repository. This research aimed to explore the leaching behaviors of cementitious waste with Pb, Cd, and Sb metallic and oxide powders in an environment simulating a silo-type radioactive waste repository. The Toxicity Characteristic Leaching Procedure (TCLP) and the ANS 16.1 standard were employed with standard and two modified solutions: concrete-saturated deionized and underground water. The compositions and elemental distribution of leachates and specimens were analyzed using an inductively coupled plasma optical emission spectrometer (ICP-OES) and energy-dispersive X-ray spectroscopy combined with scanning electron microscopy (SEM-EDS). Lead and antimony demonstrated high leaching levels in the modified leaching solutions, while cadmium exhibited minimal leaching behavior and remained mainly within the cement matrix. The results emphasize the significance of understanding heavy metals' leaching behavior in the repository's geochemical environment, which could accelerate or mitigate the reaction.

• 한국환경과학회:학술대회논문집
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• 한국환경과학회 1998년도 가을 학술발표회 프로그램
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• pp.2-4
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• 1998

Proliferation of Nocardia amarae cells in activated sludge has often been associated with the generation of nuisance foams. Despite intense research activities in recent years to examine the causes and control of Nocardia foaming in activated sludge, the foaming continued to persist throughout the activated sludge treatment plants in United States. In addition to causing various operational problems to treatment processes, the presence of Nocardia may have secondary effects on the fate of heavy metals that are not well known. For example, for treatment plants facing more stringent metal removal requirements, potential metal removal by Nocardia cells in foaming activated sludge would be a welcome secondary effect. In contrast, with new viosolid disposal regulations in place (Code o( Federal Regulation No. 503), higher concentration of metals in biosolids from foaming activated sludge could create management problems. The goal of this research was to investigate the metal sorption property of Nocardia amarae cells grown in batch reactors and in chemostat reactors. Specific surface area and metal sorption characteristics of N. amarae cells harvested at various growth stages were compared. Three metals examined in this study were copper, cadmium and nickel. Nocardia amarae strain (SRWTP isolate) used in this study was obtained from the University of California at Berkeley. The pure culture was grown in 4L batch reactor containing mineral salt medium with sodium acetate as the sole carbon source. In order to quantify the sorption of heavy metal ions to N amarae cell surfaces, cells from the batch reactor were harvested, washed, and suspended in 30mL centrifuge tubes. Metal sorption studies were conducted at pH 7.0 and ionlc strength of 10-2M. The sorption Isotherm showed that the cells harvested from the stationary and endogenous growth phase exhibited significantly higher metal sorption capacity than the cells from the exponential phase. The sequence of preferential uptake of metals by N. amarae cells was Cu>Cd>Ni. The specific surFace area of Nocardia cells was determined by a dye adsorption method. N.amarae cells growing at ewponential phase had significantly less specific surface area than that of stationary phase, indicating that the lower metal sorption capacity of Nocardia cells growing at exponential phase may be due to the lower specific surface area. The growth conditions of Nocardia cells in continuous culture affect their cell surface properties, thereby governing the adsorption capacity of heavy metal. The comparison of dye sorption isotherms for Nocardia cells growing at various growth rates revealed that the cell surface area increased with increasing sludge age, indicating that the cell surface area is highly dependent on the steady-state growth rate. The highest specific surface area of 199m21g was obtained from N.amarae cell harvested at 0.33 day-1 of growth rate. This result suggests that growth condition not only alters the structure of Nocardia cell wall but also affects the surface area, thus yielding more binding sites of metal removal. After reaching the steady-state condition at dilution rate, metal adsorption isotherms were used to determine the equilibrium distributions of metals between aqueous and Nocardia cell surfaces. The metal sorption capacity of Nocardia biomass harvested from 0.33 day-1 of growth rate was significantly higher than that of cells harvested from 0.5- and 1-day-1 operation, indicatng that N.amarae cells with a lower growth rate have higher sorpion capacity. This result was in close agreement with the trend observed from the batch study. To evaluate the effect of Nocardia cells on the metal binding capacity of activated sludge, specific surface area and metal sorption capacity of the mixture of Nocardia pure cultures and activated sludge biomass were determined by a series of batch experiments. The higher levels of Nocardia cells in the Nocardia-activated sludge samples resulted in the higher specific surface area, explaining the higher metal sorption sites by the mixed luquor samples containing greater amounts on Nocardia cells. The effect of Nocardia cells on the metal sorption capacity of activated sludge was evaluated by spiking an activated sludge sample with various amounts of pre culture Nocardia cells. The results of the Langmuir isotherm model fitted to the metal sorption by various mixtures of Nocardia and activated sludge indicated that the mixture containing higher Nocardia levels had higher metal adsorption capacity than the mixture containing lower Nocardia levels. At Nocardia levels above 100mg/g VSS, the metal sorption capacity of activate sludge increased proportionally with the amount of Noeardia cells present in the mixed liquor, indicating that the presence of Nocardia may increase the viosorption capacity of activated sludge.

• 한국도시환경학회지
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• 제18권4호
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• pp.429-437
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• 2018

본 연구에서는 중금속(Cu, Pb, Hg)과 계면활성제(SLS, ALS)의 혼합 독성을 발광박테리아(Vibrio fischeri)와 물벼룩(Daphnia magna)를 이용하여 평가하였다. 중금속에 대한 생태독성 민감도의 경우 물벼룩이 민감하게 반응하였지만 계면활성제의 경우 발광박테리아가 더 민감하게 반응하여 시험생물종 간의 민감도 차이를 확인하였다. 발광박테리아를 이용한 혼합 독성 평가 결과 대부분 실제 실험한 독성 값 P(O)이 예측된 값 P(E)보다 낮게 나타나 중금속과 계면활성제를 혼합 시 길항효과(antagonistic effect)를 보이며, 이는 음이온 계면활성제인 SLS와 ALS가 친수성 머리 부분에 음이온 형태를 띠고 있어 양이온 형태인 중금속 이온과 결합하여 실제 독성이 낮아지는 길항효과가 나타나는 것으로 보인다. 물벼룩을 이용한 혼합 독성 평가 결과 농도가 높아질수록 길항효과(antagonistic effect), 첨가효과(additive effect), 상승효과(synergistic effect)가 순서대로 나타났다. 이는 중금속에 대한 민감도가 높은 물벼룩이 농도가 높아짐에 따라 급격히 치사율이 증가하여 상승효과가 나타난 것으로 보인다.

• 한국세라믹학회지
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• 제26권5호
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• pp.601-608
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• 1989

Electrical properties of ZrF4-based heavy metla fluoride glasses were measured by the ac complex impedance method. The effects of alkali and chloride ions addition into fluoro zirconate glasses on the electrical conductivity were examined. The electrical conductivities of fluoride glasses show Arrhenian behavior in the temperature range of the experiment and were decreased by the addition of sodium fluoride up to 15mol%. Mixed alkali substitution resulted in conductivity minimum at intermediate composition which is commonly observed as mixed alkali effect' in alkali oxide glasses. Chloride ion substituted for fluoride ion was found to lower the conductivity.

• 공업화학
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• 제18권4호
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• pp.391-395
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• 2007

본 연구는 electrokinetic process (EK process)를 이용하여 20000 mg/kg의 납(Pb)으로 오염된 토양을 처리하는 과정에서 중금속이 오염토양 내부에 수산화물 형태로 침전되는 현상을 억제할 수 있는 방법을 찾기 위하여 전극교환(EK-Exchange, EK-E)과 혼합용매(0.3 M acetic acid and 0.03 M EDTA, EK-Mixed Solution, EK-M)를 사용하는 방법을 적용하였다. 혼합용매를 사용하는 경우(EK-M)에는 EDTA 0.03 M을 단독으로 사용하는 경우(EK-Blank, EK-B)보다는 약 2% 정도 낮은 제거효율을 나타내었다. 그러나, 비싼 EDTA 약품 값을 절약할 수 있다는 측면에서 보면, 이 방법도 충분히 적용 가능한 방법이다. 전극교환을 하는 경우(EK-E)에는 EDTA 0.03 M을 사용하는 경우(EK-B)보다 2% 높은 제거효율을 나타내었다. 그러나 더욱 중요한 사항은 다른 운전조건(EK-B, EK-M)과는 달리 토양 내부의 pH가 7~8 사이로 중성 부근에서 유지되었다는 점이다. 특히, 중금속의 축적이 우려되는 EK-B와 EK-M과는 달리 중금속이 특정 부위(오염토양 중앙부 또는 음극부)에 축적되지 않는다는 장점을 나타내었다.

• 한국세라믹학회지
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• 제40권6호
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• pp.583-588
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• 2003

폐기물 함유 세라믹 재료의 성형과정에서 일어나는 일차적인 중금속 안정화 과정을 알아보기 위하여 중금속(Cd, Cr, Zn) 표준용액의 농도(10-30 ppm)와 pH(pH 3-9)를 조절하여 적점토, 백토와 제올라이트에 대해 회분식 흡착실험을 행하였다. pH증가에 따라 모든 흡착원료에서 Cd와 Zn의 흡착률은 증가하였고 pH 5 이상에서는 완만한 증가를 보였다. Cr의 경우 pH증가에 따른 흡착률의 증가는 관찰할 수 없었고 오히려 적섬토와 백토를 혼합한 원료의 경우에는 pH 3에서의 흡착률에 비해 pH 5 이상에서는 50%의 흡착률 감소를 보였다 세 가지 중금속 Cd, Cr, Zn을 함께 혼합한 중금속 용액을 적점토에 대해 실험한 결과 흡착률은 Cd, Zn>Cr 순이었으나, Cu, Fe, Pb의 중금속이 추가적으로 첨가될 경우 Fe>Pb, Cu>Cr>Zn>Cd 순으로 흡착률이 변화하였다. 이는 공존 양이온의 종류가 흡착률을 좌우하며 주어진 조건에서 서로 경쟁적인 관계를 가지고 흡착하기 때문인 것으로 사료된다 한편, 공존음이온으로 Cl$^{-}$와 SO$_4$$^{2-}$ 를 1-20 ppm까지 첨가한 경우 공존 양이온의 경우와는 달리 중금속 흡착률에는 큰 영향을 주지 못하였다.