• Journal of Environmental Impact Assessment
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• v.30 no.1
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• pp.35-48
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• 2021

In this study, the assessment of field applicability of in-situ remediation of nitrate-contaminated groundwater located in Yesan-gun was performed. Zero-valent iron/bio composite media injected PRB (Permeable Reactive Barrier) and monitoring well were installed in the contaminated groundwater site and monitored main remediation indicators during the PRB operation. Nitrate, nitrite, ammonia, Fe ion, TOC, and turbidity were analyzed and the diversity and population of microorganism in the PRB installed site were investigated for the verification of effect of injected PRB. In the study site where is an agricultural area, a river flows from west to east that forms a river boundary and the southern area has an impermeable sector. It was found that nitrate flows into the river, which is similar as groundwater flow. Simulation result for the fate of nitrate in groundwater showed steady state of nitrate arrived after 3~5 years passed. However, it is just to consider current conditions with no additional input of contaminant source, if additional input of contaminant source occurs contamination dispersion and time for steady state are expected to be increased. The monitoring results showed that Fe ion, TOC and turbidity in groundwater were not clearly changed in concentration after PRB installation, which indicates adaptability of the injected PRB for remediation of groundwater with no additional harmful effect to water quality. The concentration of nitrate maintained less than 5mg/L until 42 days after PRB installation and recovered its initial concentration after 84 days passed and showed termination of reactivity of injected zero-valent iron/bio composite media for removal nitrate. Nitrite and ammonia ions found after installation of PRB indicates reductive removal of nitrate. And the outstanding increase of microorganism diversity and population of Betaproteobacteria Class which includes denitrification microorganism explains biologically reductive removal of nitrate in injected PRB.

• Clean Technology
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• v.28 no.4
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• pp.309-315
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• 2022

Research was conducted to derive the optimal operation conditions and the optimal cathode for using a DSA electrode as an anode to minimize electrode consumption during the removal of nitrogen from wastewater by the electro-chemical method. Of the various electrodes tested as cathodes, brass was determined to be the optimal electrode. It had the highest NO₃-N removal rate and the lowest concentration of residual NH₃-N, a by-product when Cl is present in the solution. Investigating the effect of current density found that when the initial concentration of NO₃-N was 50 mg L^-1, the optimal current density was 15 mA cm^-2. In addition, current densities above 15 mA cm^-2 did not significantly affect the NO₃-N removal rate. The effect of electrolytes on removing NO₃-N and minimizing NH₃-N was investigated by using Na₂SO₄ and NaCl as electrolytes and varying the reaction times. When Na₂SO₄ and NaCl are mixed at a ratio of 1.0 g L^-1 to 0.5 g L^-1 and reacted for 90 min at a current density of 15 mA cm^-2 and an initial NO₃-N concentration of 50 mg L^-1, the removal rate of NO₃-N was about 48% and there was no residual NH₃-N. On the other hand, when using only 1.5 g L^-1 of NaCl as an electrolyte, the removal rate of NO₃-N was the highest at about 55% and there was no residual NH₃-N.

• Proceedings of the Korean Environmental Sciences Society Conference
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• 2004.05a
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• pp.324-328
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• 2004

본 연구에서는 활성탄을 염화철로 표면 처리한 염화철처리 활성탄을 사용하여 지하수중의 ${NO_3}^{-}$－/-N 제거 가능성과 그 제거에 미치는 영향을 검토하고자 한 것으로 다음과 같은 결론을 얻었다. 1) 조제된 염화철 코팅 활성탄의 표면을 SEM으로 분석한 결과를 보면 활성탄의 표면에 염화철이 코팅되어 있는 것을 확인할 수 있었다. 2) 통수유속이 0.5~4 BV $hr^{-1}$/로 낮을 경우는 질산성 질소 파과시점이 비슷하였으며, 통수유속이 커질수록 활성탄의 비표면적에 접하는 시간이 짧아져서 파과시점이 짧아진 것으로 사료된다. 3) 연속컬럼 실험(3.1 L)에서 통수량 약 82 L까지는 ${NO_3}^{-}$/-N의 파과시점이 나타나지 않았으며 재생액의 농도가 0.5 M-KCl에서는 약 9 L, 1 M-KCl에서는 약 7 L의 재생액이 사용되었고, 재생 후 각각의 파과시점은 약 53 L, 59 L로 유지되었다. 1 M-KCl의 재생액을 사용하여 재생하였을 경우 두번째 재사용과 재생부터 총 질산성 질소 제거량은 약 1,531~l,357 mg/kg, 탈착량은 약 1,526~1,306 mg/kg으로 일정하였다.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2003.04a
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• pp.442-446
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• 2003

이 연구는 제주도 한림 지역에서 지하수의 수질과 오염의 특성을 규명하고자 시행되었다. 2002년 8월과 11월에 걸쳐 34개 지점에서 지하수 시료를 채취하였고, 이를 분석하여 지하수의 수질을 유형별로 분류하였다. 연구지역은 주로 (Na,Mg)-HCO$_3$ 유형이 나타나며, 일부 지점에서는 Mg-(HCO$_3$+Cl), (Ca,Mg)-HCO$_3$ 유형 등이 나타난다. 이는 지하수의 유동 경로를 따라 서로 다른 수리지화학적 반응이 일어나며, 지표 오염물질의 유입 등이 지하수의 수질에 영향을 미치고 있음을 지시한다. 질산성 질소의 경우, 국내 먹는물 수질기준치 10 mg/L를 초과한 시료는 전체 시료의 8월 조사에서 약 32%, 11월 조사에서 약 27% 이었고, 공간적 분포 특성은 비교적 낮은 고도 150m 이하의 저지대에서 채취한 시료에서 주로 나타났다. 인위적인 오염물질의 유입 가능성이 있는 지점은 전체 시료의 79.4% 이었다.

• Journal of Korean Society of Environmental Engineers
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• v.32 no.6
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• pp.599-608
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• 2010

The effect of silica(fumed) on nitrate reduction by zero-valent iron(ZVI) was studied using batch experiment. The reduction of nitrate was tested in three different aqueous media including de-ionized water, artificial groundwater and real groundwater contaminated by nitrate. Kinetics of nitrate reduction in groundwater were faster than those in de-ionized water, and first-order rate constant($k_{obs}$) of ZVI/silica(fumed) process was about 2.5 time greater than that of ZVI process in groundwater. Amendment of Silica(fumed) also decreased ammonium presumably through adsorption on silica surface. The pHs in all processes increased due to oxidation of ZVI, but the increase was lower in groundwater due to buffering capacity of groundwater. The result also showed amount of reduced nitrate increased as initial nitrate concentration increased in groundwater. Separate adsorption isotherm experiments indicated that fumed silica itself had some degree of adsorption capacity for ammonium. The overall results indicated that silica(fumed) might be a promising material for enhancing nitrate reduction by ZVI.

• Journal of Soil and Groundwater Environment
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• v.11 no.2
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• pp.38-44
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• 2006

Two sulfur-based column reactors inoculated with a bacterial consortium containing autotrophic denitrifiers were operated for 100 and 500 days, respectively and nitrate removal efficiency and the adaptation of microbial communities in the columns were monitored with column depths and time. For better understanding the adaptation phenomenon, molecular techniques including 16S rDNA sequencing and DGGE analysis were employed. Although both columns showed about 99% of nitrate removal efficiency heterotrophic denitrifiers such as Cenibacterium arsenioxidans and Geothrix fermentans were found to a significant portion at the initial stage of the 100-day reactor operation. However, as operation time increased, an autotrophic denitrifier Thiobacillus denitrificans became a dominant bacterial species throughout the column. A similar trend was also observed in the 500-day column. In addition, nitrate removal efficiencies were different with column depths and thus bacterial species with different metabolic activities were found at the corresponding depths. Especially, T. denitrificans was successfully adapted and colonized at the bottom parts of the columns where most nitrate was reduced.

• Journal of Soil and Groundwater Environment
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• v.8 no.2
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• pp.55-61
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• 2003

The objective of this study was to investigate the characteristics of nitrate removal by conducting the column test in order to see the performance of surfactant modified zeolite (SMZ) as a permeable reactive barrier material. The prediction of nitrate removal was tested using the one-dimensional advective-dispersive model fitted to the experimental breakthrough curve. A methodology for scaling up to in-situ permeable reactive barrier was also proposed. The breakthrough of nitrate in the column packed with SMZ was well predicted using linear equilibrium adsorption model. The breakthrough time and half-life obtained by breakthrough experiment with variation of flowrates were decreased with the increase of flowrates. When 10㎥/day of groundwater containing the 50 mg/l of nitrate is to be treated to satisfy the potable water quality criteria (10 mg/l) by SMZ reactive barrier, 300 tons of SMZ and about 6 years of breakthrough time will be required, suggesting that 165 million wons are needed as barrier material expenses in each 6 years besides the initial design and construction expenses and the minimal monitoring and maintenance expenses.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2002.04a
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• pp.155-158
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• 2002

질산성질소 및 탁도로 오염된 지하수공에 대하여 환경성 복원을 위한 오염방지 시설을 시범 설치하였다. 지하수공에 대한 오염 정도를 조사한 결과 PS-1, CW-1, 그리고 CW-2 공이 질산성질소로 오염되어 먹는물 수질기준을 초과하였고, CW-3 공은 탁도가 먹는물 수질기준을 초과하였다. 오염원은 지하수공 개발시 수량 확보를 위하여 그라우팅을 제대로 하지 않은 불량시공으로 인한 오염된 지표수의 유입으로 기인되었다. 금번 연구는 오염된 지하수의 환경성 복원을 위한 것으로, 오염원과 지하수를 격리시켜 오염물질의 지하수 내 유입을 방지할 수 있도록 패커 그라우팅을 완벽하게 다시 실시하였으며, 오염방지시설을 설치하였다. 이 연구를 위하여 먼저 대수층의 분포 및 특성팍악, 지하수공내 지표수의 유입구간 규명, 지하수 오염원, 오염실태, 오염경로 등을 파악하였다 오염방지시설을 설치한 후, 설치 전,후의 질산성질소와 탁도의 함량을 비교하기 위하여 수질 분석을 실시하였다. PS-1의 경우, 오염방지시설 설치전의 질산성질소 함량은 16.1 mg/L 이었으나, 설치후에는 8.1 mg/L, 7.9 mg/L로써 설치전에 비하여 51% 감소되었으며, CW-1은 10.3 mg/L에서 6.3mg/L으로 39%, 그리고 CW-2는 14.9 mg/L에서 9.0 mg/L 으로 40% 감소되었다. CW-3 공의 탁도는 157 NTU에서 0.97 NTU로 완벽하게 복원되었다.

• Bulletin of Korea Environmental Preservation Association
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• v.26 no.5_6
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• pp.51-58
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• 2004

모의 지역은 서부 호주에서 남쪽인 Busselton의 Vasse Research Station이다. 이 지역은 도살을 위해 소를 사육하는 가축사육장으로 이때문에 지하수가 질산성 질소를 비롯한 질소 화합물에 의해 심각하게 오염되었다.<중략>

• Korean Journal of Soil Science and Fertilizer
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• v.30 no.1
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• pp.23-28
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• 1997

A better understanding of nitrogen transformations in soils is essential to increase fertilizer nitrogen use efficiency. A laboratory incubation study was conducted to determine net mineralization and nitrification in selected Piedmont soils. Net mineralization and nitrification increased up to 60 days in the surface layers of Enon, Mecklenburg and Chewacla. After 60 days both processes declined up to 90 days incubation. In Wehadkee, mineralization and nitrification did not differ with incubation time. In all subsurface layers, mineralization and nitrification increased with time up to 90 days. Mineralization and nitrification differed among soils in surface and subsurface layers. These differences might be influenced by soil type related to amount of mineralization, soil aeration and nitrifying bacterial populations. A mineralization and nitrification was greater in surface layers than in subsurface layers.