• 한국지하수토양환경학회지:지하수토양환경
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• 제26권6호
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• pp.65-73
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• 2021

Since the amount of red mud, generated from aluminum smelting process as a by-product, has increased worldwide, the recycle and metal resource recovery from the red mud is becoming more important. In this study, in order to recycle the red mud as a soil stabilizer to remediate arsenic contaminated soils, neutralization of red mud was investigated. Red mud was neutralized by washing with distilled water and NaCl, CaCl₂, FeCl₃, and HCl solutions and heating at 200-800℃, and arsenic stabilization characteristics in soils were evaluated with the neutralized red mud. Although washing with distilled water was not effective in neutralizing red mud, the application of the washed red mud to soils lowered the soil pH compared to the application of untreated red mud. Among NaCl, CaCl₂, FeCl₃, and HCl solutions, washing with FeCl₃ showed the most effective in lowering pH of the red mud from pH 10.73 to pH 4.26. Application of the neutralized red mud in soils resulted in quite different arsenic stabilization efficiency depending on soil samples. In M1 soil, which showed relatively high arsenic stabilization efficiency by untreated red mud, the neutralization of red mud resulted in little effect on arsenic stabilization in soil. On the other hand, in M2 soil, which showed low arsenic stabilization efficiency by untreated red mud, the neutralization of red mud increased arsenic stabilization significantly. Soil characteristics such as clay minerals and pH buffering capacity seemed to affect reactions between red mud and soils, which resulted in different effects of the red mud application on soil pH and arsenic stabilization efficiencies.

• 한국산림과학회지
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• 제90권1호
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• pp.133-138
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• 2001

토양의 산중화 반응 결과로 나타나는 염기성 양이온의 유실과 Al의 가동성 증가는 산림 쇠퇴징후가 나타난 대기오염 지역의 공통된 특징이다. 따라서 산림토양의 산성화 민감도를 결정짓는 산중화 반응을 보다 용이하게 평가하기 위하여 토양산성도 인자를 이용한 산중화 반응 예측모형을 개발하였다. 조사대상지인 남산, 강화, 울산, 홍천의 토양산성도는 동일 지역순으로 높았으며(P<0.05), 이는 토양칼럼 실험에서 추가 산유입($16.7mmol_c/kg$)에 대한 지역별 총 산중화능($ANC_H$)과 상반된 결과였다. 모든 지역에서 염기치환과 Al 용해가 주된 산중화 기작이었으며, 총 산중화능이 낮은 지역일수록 염기치환 산중화능은 낮은 반면 Al 용해 산중화능이 높게 발휘되었다. 황산이온 흡착에 의한 산중화능은 대조지역인 홍천에서 가장 높았으나 산중화율은 6.4%로 매우 낮은 수준이었다. 토양산성도 인자를 이용하여 토양산중화 반응을 예측하기 위한 단순회귀모형과 다중회귀모형의 수정결정계수는 각각 0.52(P<0.04)와 0.89(P<0.01) 이상으로 이들 회귀모형이 토양산성화 민감도와 관련된 산중화 반응을 예측하는데 보다 용이하게 활용될 것으로 판단되었다.

• 한국지하수토양환경학회지:지하수토양환경
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• 제17권6호
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• pp.92-101
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• 2012

Korea shows the soil pH is 5.8 ~ 6.2 by many factors including the geological structure and climate condition. There is known as the cause for soil acidification by weathering of the mineral, excessive use of the chemical fertilizer, and extensively diffused acid rain. The purpose of research is environmentally-friendly material neutralization technology development utilizing the waste resources against by acid soil. The experiment analyze the physico-chemical property of the acid soil and waste resource materials (waste lime, oyster shell, bottom ash). The Batch-Test was performed under 3 stage. As a result, the acid soil showed up acid soil about 3.19. And waste lime, oyster, bottom ash showed the alkalinity with 9.62, 10.08, 9.17. In case of 1 batch-test experimental result, waste lime and oyster shell, the alkalinity was shown over 7.5 and the good efficiency was showed, on the other hands, the bottom ash showed the pH 4 the neutralization efficiency which is low. waste resource materials to be applied to 2 steps was chosen as the waste lime except the bottom ash and oyster. In 2 step batch-test experiment, it was exposed to be the most appropriate in case of doing the combination ratio of the waste lime and oyster shell with 9 : 1. It was exposed to be efficient most in the effeciency and aspect of economical efficiency combination ratio of the soil and materials was 9.6 : 0.6 with 3 step batch-test experimental result.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2003년도 추계학술발표회
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• pp.192-195
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• 2003

The hight density sludge process (HDS) is a process that has been developed to achieve greatly increased sludge densities compared to those resulting from conventional pH modification systems. This study was carried out to apprehend variation of sludge properties and removal of metals during recycling of the sludge. The principal neutralization and settlement took place in neutralization beaker and mass cylinder. Sludge was recycled, as a volumetric ratios of 20%, 40% and 60%. The pH was controlled in neutralization tanks near 9.5. The average lime consumption rate was about 10g per L of AMD. The increment of sludge density was correlated with the volumetric ratios of recycled sludge.

• 한국토양비료학회지
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• 제50권6호
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• pp.606-614
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• 2017

Amount of food waste has been increased annually in Korea and re-use of food waste as a fertilizer or soil amendment in agricultural field has been studied. Therefore, main purpose of this research was to determine optimum condition of hydrolysis for food waste management. Three different solvents, HCl, $H_2SO_4$, and KOH, were used and varied concentration at the range of 10~30% and hydrolysis time at the range of 1~3 hours were evaluated. In general, reduction rate of food waste was increased when concentration of solvent and hydrolysis time was increased except when KOH was used. Among different solvents, concentration, and hydrolysis time, the highest reduction rate (97.79%) was observed when 30% of HCl was used with temperature of $140^{\circ}C$ at 2 hours of hydrolysis time. In addition, neutralization effect of alkalic materials, shell waste (SW) and egg shell (ES) was evaluated. Both SW and ES increased pH of finished acid hydrolysis solution up to 7.61 indicating that neutralization effect of SW and ES was sufficient for finished acid hydrolysis solution. Contents of organic matter was also at the range of 10.7~13.04% and 5.53~8.04% respectively when HCl and $H_2SO_4$ were used as solvent. Overall, hydrolysis technique can be used to manage food waste with selected optimum condition in this study and characteristics of finished hydrolysis solution after neutralization might be suitable for soil amendments.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2001년도 총회 및 춘계학술발표회
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• pp.206-209
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• 2001

This study presents the leaching characterization of heavy metals according to changes of pH by ANC test on slag produced in electric arc furnace, bottom ash produced in coal-fired plants and their recycling products. Availability test was performed to assess the fraction of the total concentration that under worst environmental conditions could become available for leaching. TCLP, KLT(Korea Leaching Test) and KLTS(Korea Leaching Test of Soil contamination) were carried out to compare the leaching capacity and to estimate the adequacy of regulatory leaching test. Results from regulatory leaching tests could be misleading because the variable ANC of wastes can lead to very different final leachate pHs. The final pH of the regulatory test is not the ambient pH in the disposal environment, the actual solubilities of contaminants in the field may be entirely different from those predicted by these regulatory tests. Leaching behaviour of by-products was changed by recycling processes, therefore acid neutralization capacity and availability of new products, not leaching concentration by one batch regulatory test, are necessary to determine the method of recycling.

• 한국지하수토양환경학회지:지하수토양환경
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• 제26권1호
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• pp.34-44
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• 2021

Acid mine drainage (AMD) resulting from pyrite oxidation in mining areas, subsequently leads to soil acidification accompanied by lowering pH and high concentration of metals and metalloids in its surrounding environment. Regarding to this, the microbial amelioration has been considered as a promising option for a more cost-effective and eco-friendlier countermeasure, compared to the use of alkaline chemicals. This study was aimed to evaluate influencing factors in microbially-mediated amelioration of acidic soil spiked by simulated AMD. For this, microcosm experiments were conducted by acid-neutralizing bacterial consortium (dominated by Klebsiella sp. and Raoultella sp.) under the various conditions of AMD spikes (0-2,500 mg SO42-/L), together with acidic mine soil (0-100 g) or sphagnum peat (0-5 g) in the 200 mL of nutrient medium. The employed bacterial consortium, capable of resisting to high level of sulfate concentration (up to 1,500 mg SO42-/L) in low pH, generated the ammonium while concomitantly reduced the sulfate, subsequently contributing to the effective soil stabilization with an evolution of soil pH up to neutral. Furthermore, it demonstrates that suitable condition has to be tuned for successful microbial metabolism to facilitate with neutralization during practical application.

• 한국지하수토양환경학회지:지하수토양환경
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• 제19권3호
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• pp.142-152
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• 2014

In this study, generic characteristics of the acid mine drainage (AMD), removal efficiency of iron, aluminium and manganese by chemical treatment, electrolysis and hybrid process using electrolysis after neutralization were evaluated. The pH of AMD was inversely proportional to the rainfall. In dry-season, the average pH of AMD was ranged from 4.5 to 5.5, showing slight variation. However, the pH of AMD was gradually decreased along with rainfall and dropped to 3.02 in September showing the greatest rainfall. Removal efficiency of heavy metals by chemical treatments using three different neutralizing agents or by electrolysis was low. However, a hybrid process performed with electrolysis after addition of neutralization shows higher removal capacity for heavy metal ions than neutralization-alone and electrolysisalone process.

• 수산해양교육연구
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• 제27권6호
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• pp.1764-1782
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• 2015

The purpose of this study is to investigate the understanding on the acid-base, acid rain and soil acidification of the elementary students. The participants in the current study were 280 6th graders from a elementary school in Gyeongnam Province. A questionnaire consists of four categories: understanding of (a) acid-base basic knowledge, (b) acid rain and (c) soil acidification. (d) In addition, students were asked to comment about the introduction of the acid rain experiment in the science textbook. The results are as follows; First, the results regarding acid-base basic knowledge. They know the classification, characteristics, and properties of acid-based solutions well but they don't know the acid-base neutralization, examples using properties and application in real life. Second, the results regarding acid rain, students know the definition and damage of acid rain but they don't know the causing substances, emission source and way of solution of acid rain for lack of knowledge. Third, the results regarding soil acidification was the well-known part for the students because they had continued learning about the soil from the lesson of acid rain. Also, we looked into the difference in gender and region about the understanding of acid-base, acid rain and soil acidification. According to the gender of the data about the understanding of acid-base, acid rain and soil acidification, the percentage of correct answers of female was higher than male's. Also we expected that urban students were higher than rural students on the understanding of acid-base, acid rain and soil acidification, but the understanding of urban students were similar to rural students. Fourth, we got positive answers and negative answers to the introduction of acid rain experiment. Most of the positive opinion were I want to know a lot acid rain experiment", followed by "It is possible to prevent the risk of the damage and It seems to having fun and new order. Most of the negative opinion were Acid rain experiment may be difficult and complicated followed by Just a theory in the book is enough, Acid rain experiment were boring and not fun, Acid rain experiment is dangerous, There are many to study in this order.

• Asian Journal of Atmospheric Environment
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• 제7권4호
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• pp.217-226
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• 2013

The collection of TSP and $PM_{2.5}$ aerosols has been made at the Gosan Site of Jeju Island during 2008-2011, and their ionic and elemental species were analyzed, in order to examine the seasonal variation and characteristics of aerosol compositions. The anthropogenic components ($NH_4{^+}$, $nss-SO_4{^{2-}}$, $NO_3{^-}$, S, Zn, Pb) and the soil components ($nss-Ca^{2+}$, Al, Fe, Ca) showed high concentrations in spring as the prevailing westerly wind, but the concentrations of the sea-salt components ($Na^+$, $Cl^-$) were high in winter. In TSP, the neutralization by $NH_3$ increased in summer, but the neutralization by $CaCO_3$ increased in spring and fall seasons. The organic acids ($HCOO^-$, $CH_3COO^-$) contributed to the acidification of the aerosols by only 5.0%, so the acidification could be mostly contributed by the inorganic acids ($SO_4{^{2-}}$, $NO_3{^-}$). From the examination of the source origins by factor analysis, the compositions of TSP were influenced by the order of soil > anthropogenic > marine, on the other hand, those of $PM_{2.5}$ were by the order of anthropogenic > marine > soil. The backward trajectory analyses showed that the concentrations of $NH_4{^+}$, $nss-SO_4{^{2-}}$, $NO_3{^-}$ and $nss-Ca^{2+}$ increased highly when the air masses had moved from China continent into Gosan area of Jeju Island.