• Proceedings of the Korean Geotechical Society Conference
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• 2004.03b
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• pp.897-903
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• 2004

Waste lime used in this study is producted as a by-product in the manufacturing process of making $Na_2CO_3$ from local chemical factory in Incheon. Currently about 320 millon tons of waste lime are accumulated and annually 100,000 tons are producted. Reuse of waste lime mixed with soil for banking and backfill materia in civil works was analysed in this study. This study was Carried out to investigate the geotechnical and environmental characteristics on field application. Field investigations were conducted on the road construction site in Incheon. This study presents the results of the engineering characteristics in field test and the leaching characteristic of waste lime in laboratory column tests. Countermeasure for reduction of environmental effects was suggested from the test results.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2006.04a
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• pp.111-114
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• 2006

The effects of indigenous bacteria on geochemical behavior of As in As-contaminated sediments (Hwachon mine and Myoungbong mine) after biostimulation with a variety of carbon sources were investigated under anaerobic condition. In Hwachon sediment, As was dramatically extracted from nonsterile sediment with time, reaching the highest concentration of $500{\mu}g/L$. The As leaching was likely caused by microbial dissolution of Fe oxides/oxyhydroxides with which As had been coprecipitated. However, in the case of Myoungbong sediment supplied with glucose, dissolved As decreased with time likely due to production of As sulfide(s) and subsequent precipitation, which resulted from bacterial reduction of $SO_4^{2-}$. The results implied that bacterial in-situ stabilization of As In subsurface has a potential to be practically applied.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 1999.10a
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• pp.65-68
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• 1999

A plasma melting system to vitrify ny ash from MSW(Municipal Solid Waste) incinerator has been operated in SHI(Samsung Heavy Industries) since 1996. Waste feeding rate was 200kg/hr. with maximum working power of 500㎾. Because of high melting temperature of fly ash, bottom ash was used as an additive to decrease melting temperature. Data analysis for discharged slag shows volume reduction up to 30% and no leaching of heavy metals such as Pb, Cd, Cr which were an obstacle for landfill and recycle. Atmospheric pollution gas like nitrogen oxides, carbon monoxide, and PCDD/PCDF were restrained below the regulatory limit.

• Journal of the Korea Institute of Military Science and Technology
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• v.6 no.2
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• pp.9-19
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• 2003

Nitrogen oxide gases which were produced by spontaneous reaction of nitrocellulose(NC) in the single base propellant accelerate the decomposition of propellant, and result in the reduction of shelf life. The amount of nitrogen oxide was reduced by the addition of 0.3wt% $CaCO_3$ to conventional stabilizer(DPA) and down of the solvent leaching temperature from $64^{\circ}C$ to $56^{\circ}C$, which extended the shelf life of the single base propellant as much as twice compare with commercial propellant. The perforation diameter increase of propellant from 0.64mm to 0.77mm could compensate for the drop of burning rate which was caused the addition of $CaCO_3$.

• Journal of Animal Environmental Science
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• v.1 no.2
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• pp.173-178
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• 1995

The aim of this study was to describe the NO$_3$ leaching in grassland ecosy-stems. Field study was performed in the southwestern district of Germany from 1991 to 1993. The study included 3 different slurry application, conventional slurry application, 50% reduced slurry application and without slurry application. On each plot were installed 3 ceramic cups at 120cm depth. Samples were collected twice a month and analysed for NO$_3$ colorimetrically using a Tecator Auto-Analyzer. Percolation was calculated as the difference between precipitation and potential evapotranspiration. The NO$_3$ concentration in soil water was remarkably variable during the year. The average NO$_3$ concentration during the experiment was the lowest (8.5mg/l) without slurry application and the highest with 240kg N/ha cattle slurry (25.3mg/l). the NO$_3$-N leached per year were respectively 29, 23, and 12kg/ha in case of 240, 120 and 0kg N/ha when cattle slurry was applied. The conventional feeding density of cattle husbandry in the district caused the NO$_3$ contamination in ground water. When the amount of cattle slurry applied was reduced to 50%, the NO$_3$ loading in ground water was reduced greatly. Therefore, the reduction policy of cattle slurry can positively contribute to the prevention of the NO$_3$-contamination in groundwater.

• Journal of Wetlands Research
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• v.22 no.3
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• pp.171-177
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• 2020

To improve the nitrogen reduction capability of stormwater treatment systems subjected to intermittent saturation, organic materials are often added as filter media. However, these materials can be an additional source of organic carbon and increase the chemical oxygen demand (COD) in the outflow. In this study, different types of organic filter media were subjected to a batch leaching test to observe and quantify the release of COD. Results reveal that the initial pH of the tap water used for soaking which is 7.5-7.7 is conducive to the release of organics from the media to the leachate. The highest amount of COD released was observed in yard clippings and woodchip followed by compost and bark mulch. The leaching of organics also increased as the size of the media decreases due to higher surface area per volume. In addition, empirical regression analysis predicted that COD from these organic media will be exhausted from the material in 3-5 months to up to 26 months depending on the type of media. The results of this study can serve as a guide in estimating the potential release of COD in organic media in order to ensure their safe application in stormwater treatment facilities.

• Journal of the Korea Organic Resources Recycling Association
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• v.19 no.3
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• pp.54-62
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• 2011

This study was undertaken to investigate the effects of bone waste on the conservation of nitrogen in aerobic composting process by inducing the struvite crystallization, which was known as a powerful method for conservation of nitrogen in composting reaction. Bone waste was dried at oven and crushed to less than 3 mm prior to use. It was found phosphorus content in bone waste was about 20.9% of the fixed solids from the leaching experiments using sulfuric acid. Addition of seed compost affected the progress of composting reaction substantially. In case seed compost was not used, the duration of initial low pH was greater than seed compost was added. This prolonged acidic pH may have a beneficial effect on the leaching of P from the bone waste and struvite crystallization. The struvite crystallization and resulting conservation of nitrogen by addition of bone waste was confirmed by both reduction in ammonia loss and increased ammonia content in compost. However the level of struvite crystallization observed with bone waste addition may be less than the cases water-soluble phosphate salts were used.

• Resources Recycling
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• v.28 no.3
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• pp.45-52
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• 2019

$TiO_2$ as a raw material for producing titanium can be produced by carbon reduction of natural ilmenite ores over 1823 K and acid leaching of the obtained titanium-rich slag. However, the conventional process can cause very high energy consumption and a large amount of leaching residues. In the present study, we proposed the sulfurization of $FeTiO_3$ with $Na_2SO_4$ at temperatures below 1573 K, which can separate Fe in $FeTiO_3$ as the FeS based sulfide phase and Ti as the $TiO_2-Na_2O$ based oxide phase. This study is a fundamental study for sulfurization of $FeTiO_3$ to investigate the influence of reducing atmosphere, reaction temperature and the sulfur/Fe ratio on the separability and distribution behaviors of of Fe, Ti, and Na between the oxide phase and the sulfurized phase. At 1573 K and carbon saturation condition, the Fe can be separated from $FeTiO_3$ as Fe-C-S metal and a part of FeS, and the concentration of Fe in oxide decreased to 4 mass% after sulfurization.

• Korean Journal of Materials Research
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• v.11 no.2
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• pp.76-81
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• 2001

In order to recover Au and Pd from the leaching solution of various electronic wastes by electrowinning, the electrochemical behavior of Au and Pd in hydorchloric acidic solution was investigated by means of voltammetry. The reduction potential of Au ion was 800mV and the limiting current appeared at 470mV in electrolytic solution of gold. The reduction potential of Pd ion was 500mv and the limiting current appeared at 150mV in electrolytic solution of Palladium. However, in Au-Pd electrolytic solution, the Potentials for reduction and the limiting current of Au decreased as the content of Pd in electrolyte increased, and the potentials for the limiting current of Au and Pd closed nearest together when percentage of Pd electrolytic solution was 37v71% in Au-Pd electrolyte.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.37 no.3
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• pp.541-547
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• 2017

In Yongwon channel, its natural flow of seawater is blocked by the construction of Busan Newport including the container berth. The channel was transformed into a narrow and long one, where it is possible that ships are only allowed to pass through the north-side channel of Gyeonmado located at the point of river mouth to Songjeongcheon. So it is considered that the changes in the terrain characteristics of Yongwon channel is likely to alter the circulation of sea water, thereby changing its water quality. Contaminants are accumulated from the sediment release. In this study, before and after dredging the sediment release test was performed. As a result, after the sediment dredging is performed, the reduction rate was higher at the same point. The results show that the water quality can be improved by dredging. Each group (A~C) reduction rate of the evaluation of the reduction rate of 4.64% T-N, 18.00%, 18.59%, respectively. T-P rate of 24.75% reduction, 24.17%, 44.08%, respectively. COD reduction rate was 18.57%, 19.76%, 38.08%, respectively. These results can be used as basic data for controlling the contamination by dredging in Yongwon channel.