• 한국지하수토양환경학회지:지하수토양환경
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• 제18권3호
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• pp.109-118
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• 2013

Characteristics of the transport of zero-valent iron nanoparticles (nZVI) in an aquifer were investigated to evaluate an application of nZVI-based reactive zone technology. Main flow direction of groundwater was north. Preferential flow paths of the groundwater identified by natural gradient tracer test were shown northeast and northwest. The highest groundwater velocity was $4.86{\times}10^{-5}$ m/s toward northwest. When the breakthrough curves obtained from the gravity injection of nZVI were compared with the tracer curves, the transport of nZVI was retarded and retardation factors were 1.17 and 1.34 at monitoring wells located on the northeast and northwest, respectively. The ratios of the amount of nZVI delivered to the amount of tracer delivered at the two wells mentioned above were 24 and 28 times greater than that of the well on the main flow direction, respectively. Attachment efficiency based on a filtration theory was $4.08{\times}10^{-2}$ along the northwest direction that was the main migration route of nZVI. Our results, compared to attachment efficiencies obtained in other studies, demonstrate that the mobility of nZVI was higher than that of results reported in previous studies, regardless of large iron particle sizes of the current study. Based on distribution of nZVI estimated by the attachment efficiency, it was found that nZVI present within 1.05 m from injection well could remove 99% of TCE within 6 months.

• 한국토양비료학회지
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• 제33권2호
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• pp.71-78
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• 2000

사과 과수원 토양(송정통, the fine loamy, mesic family of Typic Hapludults)을 층위별로 채취하여 토양 수리적 특성과 누적공극분포를 조사하고 표토인 Ap1층과 점토집적층인 B1층에서 각각 토양코아시료 (지름 7.4 cm, 높이 7.4 cm)를 채취하여 포화조건에서 $Cl^-$와 $Cu^{2+}$로 혼성치환실험을 수행하고 그 출현곡선으로부터 선택류(選擇流)를 검증하고자 하였다. Ap1층과 B1층은 사질 식양토로 같은 토성이나 Ap1층의 포화수리전도도는 $2.0cmhr^{-1}$로 B1층($0.27cm hr^{-1}$)의 약 7배에 달하였다. C층은 포화수리전도도 $5.2cmhr^{-1}$인 구조가 없는 사양토로 물과 용질의 이동을 제한하는 역할이 가장 낮을 것으로 판단되었다. 누적 공극분포에서 Ap1층과 B1층의 대공극량(토양수분포텐셜 - 6 kpa에 해당하는 지름 $49{\mu}m$ 이상의 공극)은 각각 총 공극량의 24%, B1층은 14%이었다. 염소출현곡선에서 Ap1층 코아와 B1층 코아의 수력학적 분산계수는 각각 $34cm^2hr^{-1}$, $1.3cm^2hr^{-1}$이었고 이때 B1층 코아의 지연계수는 1인 반면 Ap1층 코아는 0.6으로 부동수분과 유동수분의 분배가 일어났다. 양이온 치환용량이 Ap1층이 B1층보다 높음에도 불구하고 Ap1층 코아의 구리지연효과가 B1층보다 더 작게 나타났다. 이 결과는 포화수리전도도와 대공극 함량이 큰 Ap1층에서 선택류(選擇流)가 일어날 수 가능성을 보여 주었다. 그러나 투수성이 좋은 모재층을 가진 이 토양단면에서 Ap1층에서 선택류(選擇流)가 일어난다 하더라도 B1층에 의해 제한될 것으로 사료된다.

• Membrane and Water Treatment
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• 제14권2호
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• pp.95-106
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• 2023

In the developing country like India, groundwater is the main sources for household, irrigation and industrial use. Its contamination poses hydro-geological and environmental concern. The hazardous waste sites such as landfills can lead to contamination of ground water. The contaminants existing at such sites can eventually find ingress down through the soil and into the groundwater in case of leakage. It is necessary to understand the process of migration of pollutants through sub-surface porous medium for avoiding health risks. On this backdrop, the present paper investigates the behavior of pollutants' migration through porous media. The laboratory experiments were carried out on a soil-column model that represents porous media. Two different types of soils (standard sand and red soil) were considered as the media. Further, two different solutes, i.e., non-reactive and reactive, were used. The experimental results are simulated through numerical modeling. The percentage variation in the experimental and numerical results is found to be in the range of 0.75- 11.23 % and 0.84 - 1.26% in case of standard sand and red soil, respectively. While a close agreement is observed in most of the breakthrough curves obtained experimentally and numerically, good agreement is seen in either result in one case.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2008년도 추계 학술발표회
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• pp.1512-1517
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• 2008

Laboratory column tests were conducted in this study using $Cl^-$ tracers on Jumunjin sand to analyze contaminant transport in mixed contaminated soils. Results obtained from clean soils and soils containing residual diesel verified heterogeneous distribution of residual diesel, and clear acceleration of solute movement. In addition, asymmetric breakthrough curves indicated development of immobile region where solute movement becomes stagnant and creates tailing phenomenon.

• 상하수도학회지
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• 제30권3호
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• pp.263-270
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• 2016

Recent Engineered nanoparticles were increasingly exposed to environmental system with the wide application and production of nanomaterials, concerns are increasing about their environmental risk to soil and groundwater system. In order to assess the transport behavior of silver nanoparticles (AgNPs), a saturated packed column experiments were examined. Inductively coupled plasma-mass spectrometry and a DLS detector was used for concentration and size measurement of AgNPs. The column experiment results showed that solution chemistry had a considerable temporal deposition of AgNPs on the porous media of solid glass beads. In column experiment, comparable mobility improvement of AgNPs were observed by changing solution chemistry conditions from salts (in both NaCl and $CaCl_2$ solutions) to DI conditions, but in much lower ionic strength (IS) with $CaCl_2$. Additionally, the fitted parameters with two-site kinetic attachment model form the experimental breakthrough curves (BTCs) were associated that the retention rates of the AgNPs aggregates were enhanced with increasing IS under both NaCl and $CaCl_2$ solutions.

• Environmental Engineering Research
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• 제13권3호
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• pp.141-146
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• 2008

Transport of Escherichia coli ATCC 11105 through porous media was investigated in this study using two sets of column experiments to quantify the attachment-related parameters (sticking efficiency, attachment rate coefficient and filter factor). The first set of experiments was performed in quartz sand under different ionic strength conditions (1, 20, 100, 200 mM) while the second experiments were carried out in quartz sand mixed with metal oxyhydroxide-coated sand (0, 5, 10, 25%). The breakthrough curves of bacteria were obtained by monitoring effluent, and then bacterial mass recovery and attachment-related parameters were quantified from these curves. The first experiments showed that the mass recoveries were in the range of 13.3 to 64.7%, decreasing with increasing ionic strength. In the second experiments, the mass recoveries were in the range of 15.0 to 43.4%, decreasing with increasing coated sand content. The analysis indicated that the sticking efficiency, attachment rate coefficient and filter factor increased with increasing ionic strength and coated sand content. The value of filter factor in the first experiments ranged from 1.45 e-2 to 6.72 e-2 1/cm while in the second experiments it ranged from 2.78 e-2 to 6.32 e-2 1/cm. Our filter factor values are one order of magnitude lower than those from other studies. This discrepancy can be attributed to the size of sand used in the experiment. The analysis demonstrated that the travel distance of bacteria estimated using the filter factor can be varied greatly depending on the solution chemistry and charge heterogeneity of porous media.

• 한국지하수토양환경학회지:지하수토양환경
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• 제11권1호
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• pp.14-22
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• 2006

Cd과 Cr(VI)으로 동시에 오염된 지하수 정화에 반응벽체 공법을 적용하기 위하여 환원능과 흡착능을 동시에 가지는 새로운 반응 물질인 Fe-loaded zeolite의 반응성을 실내 주상실험을 통해 평가하였다. Cd과 Cr(VI)을 동시에 포함한 오염용액을 반응물질이 충진된 칼럼에 주입하고, 이 칼럼을 통과한 유출수에서의 Cd과 Cr(VI) 농도를 측정하여 파과곡선을 얻는 방법으로 본 주상실험을 수행하였다. 유출수의 농도 분석 결과 Cd의 파과는 Cr(VI)의 파과곡선이 완료되는 시점까지 전혀 관찰되지 않아, 반응물질의 전반적인 효율은 Cr(VI)에 대한 반응성에 의해 결정됨을 알 수 있었다. Cr(VI)의 파과곡선은 파과 시작점이 다소 지체되고 파과의 진행 속도도 느려지며 파괴곡선의 상대농도 값이 1까지 증가하는 양상을 나타내었다. 이러한 Cr(VI) 파과곡선의 양상을 정량적으로 묘사하기 위하여 형상계수라고 하는 새로운 계수 ${\alpha}$와 ${\beta}$를 정의하고, 이를 오염물질의 이동방정식에 적용함으로써 파과곡선의 지체 정도와 기울기 정도를 나타내었다. 초기 주입 용액의 농도가 증가할수록 ${\alpha}$값은 감소하였고, 이로부터 파과곡선의 시작 시점이 빨라 지는 것을 알 수 있었다. 또한 초기 주입 용액의 속도가 증가할수록 ${\beta}$ 값이 감소하였으며, 이로부터 파과곡선의 기울기가 점차 가팔라지는 것을 알 수 있었다. 이를 통해 Fe-loaded zeolite를 반응벽체 내 반응물질로 적용할 경우, Fe-loaded zeolite는 지하수 상에 존재하는 서로 다른 이온 형태의 중금속인 Cd과 Cr(VI)을 효과적으로 동시에 제거할 수 있음을 획인하였으며 이때, Fe-loaded zeolite를 통한 Cr(VI)의 파과는 지하수 흐름이 빠를수록 파과의 진행이 더욱 급격히 나타날 것이며 오염농도가 높은 지하수일수록 파과의 시점이 빠르게 나타나 반응물질은 그 사용 한계 에 다다르게 될 것임을 예측할 수 있었다.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2004년도 총회 및 춘계학술발표회
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• pp.77-82
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• 2004

Quantifying rates of microbial processes under subsurface conditions is difficult, and is most commonly approximated by laboratory studies using aquifer materials. In this study a single-well, 'push-pull' test method is adapted for the in situ determination of denitrification rates in groundwater aquifers. The rates of stepwise reduction of nitrate to nitrite, nitrous oxide, and molecular nitrogen were determined by performing a series of push-pull tests at an experimental well field of Korea University. A single Transport Test, one Biostimulation Test, and four Activity Tests were conducted for this study. Transport tests are conducted to evaluate the mobility of solutes used in subsequent tests. These included bromide (a conservative tracer), fumarate (a carbon and/or source), and nitrate (an electron acceptor). At this site, extraction phase breakthrough curves for all solutes were similar, indicating apparent conservative transport of the solutes prior to biostimulation. Biostimulation tests were conducted to stimulate the activity of indigenous heterotrophic denitrifyinc microorganisms. Biostimulation was detected by the simultaneous production of carbon dioxide and nitrite after each injection. Activity tests were conducted to quantify rates of nitrate, nitrite, and nitrous oxide reduction. Estimated zero-order degradation rates decreased in the order nitrate '||'&'||'gt; nitrite '||'&'||'gt; nitrous oxide. The series of push-pull tests developed and field tested in this study should prove useful for conducting rapid, low-cost feasibi1ity assessments for in situ denitrification in nitrate-contaminated aquifers.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2003년도 총회 및 춘계학술발표회
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• pp.188-191
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• 2003

Sing]e-well-push-pull tests were developed for use in assessing the feasibility of in-situ aerobic cometabolism of chlorinated aliphatic hydrocarbons (CAHs). The series includes Transport tests, Biostimulation tests, and Activity tests. Transport tests are conducted to evaluate the mobility of solutes used in subsequent tests. These included bromide or chloride (conservative tracers), propane (growth substrate), ethylene, propylene (CAH surrogates), dissolved oxygen (electron acceptor) and nitrate (a minor nutrient). Tests were conducted at an experimental well field of Oregon State University. At this site, extraction phase breakthrough curves for all solutes were similar, indicating apparent conservative transport of the dissolved gases and nitrate prior to biostimulation. Biostimulation tests were conducted to stimulate propane-utilizing activity of indigenous microorganisms and consisted of sequential injections of site groundwater containing dissolved propane and oxygen. Biostimulation was detected by the increase in rates of propane and oxygen utilization after each injection. Activity tests were conducted to quantify rates of substrate utilization and to confirm that CAH-transforming activity had been stimulated. In particular, the transformation of injected CAH surrogates ethylene and propylene to the cometabolic byproducts ethylene oxide and propylene oxide provided evidence that activity of the monooxygenase enzyme system, responsible for aerobic cometabolic transformations of CAHs had been stimulated. Estimated zero-order transformation rates decreased in the order propane > ethylene > propylene. The series of push-pu3l tests developed and field tested in this study should prove useful for conducting rapid, low-cost feasibility assessments for in situ aerobic cometabolism of CAHs.

• 한국환경과학회지
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• 제16권10호
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• pp.1147-1155
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• 2007

The applicability of in situ biobarrier or microbial filter technology for the remediation of groundwater contaminated with chlorinated solvent was investigated through column study. In this study, the effect of packing materials on the reductive dechlorination of PCE was investigated using Canadian peat, Pahokee peat, peat moss and vermicompost (or worm casting) as a biobarrier medium. Optimal conditions previously determined from a batch microcosm study was applied in this column study. Lactate/benzoate was amended as electron donors to stimulate reductive dechlorination of PCE. Hydraulic conductivity was approximately $6{\times}10^{-5}-8{\times}10^{-5}\;cm/sec$ and no difference was found among the packing materials. The transport and dispersion coefficients determined from the curve-fitting of the breakthrough curves of $Br^-$ using CXTFIT 2.1 showed no difference between single-region and two-region models. The reductive dechlorination of PCE was efficiently occurred in all columns. Among the columns, especially the column packed with vermicompost exhibited the highest reductive dechlorination efficiency. The results of this study showed the promising potential of in situ biobarrier technology using peat and vermicompost for the remediation of groundwater contaminated with chlorinated solvents.