• Journal of Soil and Groundwater Environment
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• v.10 no.5
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• pp.25-36
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• 2005

Several metalliferous and coal mines, including Myungjin, Seojin and Okdong located at the upper watershed of Okdong stream, were abandoned or closed since 1988 due to the mining industry promotion policy. Thus these disposed an enormous amount of mining wastes without a proper treatment facilities, resulting in water pollution in the downstream areas. Acid mine drainage (AMD) and waste water effluents from the closed coal mines were very strongly acidic showing pH ranges of 2.7 to 4.5 and had a high level of Total Dissolved Solids (TDS) showing the ranges of 1,030 to 1,947 mg/L. Also heavy metal concentrations in these samples such as Fe, Cu, Cd and anion such as sulfate were very high. Concentrations of water soluble heavy metals in the Okdong streams were in the orders of Fe>Al>Mn>Zn>Cu>Pb>Cd, indicating Fe from the AMD and waste water effluents contributed greatly to the quality of water and soil in the lower watershed of Okdong stream. Copper concentrations in the effluents from the tile drainage of mine tailings dams were highest during the raining season. Water Pollution Index (WPI) of the surface water at the upper stream of Okdong river where AMD of the abandoned coal mines was flowed into main stream were in the ranges of 16.3 to 47.1. On the other hand, those at the mid stream where effluents from tailings dams and coal mines flowed into main stream were in the WPI ranges of 10.6 to 19.5. However, those at the lower stream were ranged from 10.6 to 14.9. These results indicated that mining wastes such as AMD and effluents from the closed mines were the major source to water pollution at the Okdong stream areas.

• Horticultural Science & Technology
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• v.28 no.4
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• pp.574-579
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• 2010

Waste nutrient solution (WNS) that was the drained nutrient solution of Horticultural Research Institute of Japan for culture tomato in perlite hydroponics showed $1.9-2.4dS{\cdot}m^{-1}$ of EC and 5.7-7.1 pH from April to July. Although ${NH_4}^+-N$ concentration of WNS decreased remarkably, the other nutrients did not change significantly, as compared with supplied solution. There were no significant differences in plant height, stem diameter, and the other growth characteristics of tomato plants grown by 2 fertigation nutrient solutions; BHF (Bountiful Harvest Fertilizer, 10% of N, 13% of $PO_4$, 13% of K, 0.05% of B, 0.05% of Zn, and 0.0023% of Cu that made in Korea) and Megasol (11% of N, 8% of $PO_4$, 34% of K, 0.032% of Mn, 0.002% of B, 0.048% of Fe, 0.0122% of Zn, and 0.0023% of Cu that made in Belgium.); however, the chlorophyll content of tomato leaf was highest in WNS. The fresh and dry weight of tomato plants were higher in 3 fertigation treatments than irrigation of tap water, while there were no significant differences in fresh and dry weight among the 3 fertigation treatments. The mineral content of tomato leaf also did not show any differences among the 3 fertigation treatments and any regular tendency in all minerals. Total yield, fruit weight and fruit numbers of tomato were higher in WNS, followed by Megasol, BHF and control, although there were not any difference among the 3 fertigation nutrient solution treatments. BER(blossom-end rot)of tomato fruits decreased in fertigation treatments, especially, fruits grown in WNS and BHF showed lower BER. However, the transpiration rate of leaf was higher in control, followed by BHF, WNS and Megasol, The fruit size and soluble solids content was higher in 3 fertigation nutrient treatments than control. These results suggest that WNS can be used for fertigation solution in tomato because yield and quality of tomato fruit grown in WNS fertigation treatment were similar to those in 2 fertigation nutrient solutions treatments(BHF, Megasol).

• KOREAN JOURNAL OF CROP SCIENCE
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• v.56 no.4
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• pp.299-307
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• 2011

This study was carried out to obtain the basic data for selecting the cultivatable bioenergy crops through application of solidified sewage sludge in reclaimed lands. The experimental plots consisted of the mixing with solidified sewage sludge plot (SS50), the covering with solidified sewage sludge plot (SS100), and the original reclaimed land plot (ORL) on reclaimed land for the intended landfill in Sudokwon Landfill Site Management Corporation (SLC). The growth of energy crops (Geodae-Uksae 1, Miscanthus sacchariflorus, and Phragmites australis) were investigated from May to October, 2010 in each experimental plot. The soil from ORL showed higher salinity with high contents of exchangeable $Na^+$ cation than that of SS50 and SS100. Soil properties on reclaimed land used in this study must be improved by increasing the buffering capacity of saline with the treatment of solidified sewage sludge due to the fact that the contents of organic matter (OM) in both of SS50 and SS100 were higher than that of the ORL. Thus the growth of energy crops cultivated in the solidified sewage sludge plots were better than in ORL. Geodae-Uksae 1 which showed an excellent adaptability on reclaimed land treated with the solidified sewage sludge has considerably higher biomass than those of other energy crops (M. sacchariflorus and P. australis). This study suggested that Geodae-Uksae 1 is the most suitable biomass feedstock crop for bioenergy productions, and the solidified sewage sludge may be possible to utilize as a soil cover materials for cultivation of bioenergy crops in reclaimed land.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.6 no.3
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• pp.217-224
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• 2008

In deep geological disposal system, the integrity of a disposal canister having spent fuels is very important factor to assure the safety of the repository system. This disposal canister is one element of the engineered barriers to isolate and to delay the radioactivity release from human beings and the environment for a long time so that the toxicity does not affect the environment. The main requirement in designing the deep geological disposal system is to keep the buffer temperature below 100$^{\circ}C$ by the decay heat from the spent fuels in the canister in order to maintain the integrity of the buffer material. Also, the disposal canister can endure the hydraulic pressure in the depth of 500 m and the swelling pressure of the bentonite as a buffer. In this study, new concept of the disposal canister for the CANDU spent fuels which were considered to be disposed without any treatment was developed and the thermal stability and the structural integrity of the canister were analysed. The result of the thermal analysis showed that the temperature of the buffer was 88.9$^{\circ}C$ when 37 years have passed after emplacement of the canister and the spacings of the disposal tunnel and the deposition holes were 40 m and 3 m, respectively. In the case of structural analysis, the result showed that the safety factors of the normal and the extreme environment were 2.9 and 1.33, respectively. So, these results reveal that the canister meets the thermal and the structural requirements in the deep geological disposal system.

• Journal of Korean Society of Environmental Engineers
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• v.30 no.8
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• pp.789-797
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• 2008

This study was conducted to investigate removal characteristics of gaseous trimethylamine(TMA) through biofilter packed with waste tire-chips. The sludge in this experiment was collected from an activated sludge operated in a wastewater treatment facility treating malodorous pollutants. The nominal amount of collected sludge was inoculated through packing materials in the filter. The removal efficiencies for varying concentrations and SVs(Space velocity) were assessed based on TMA, COD$_{Cr}$, NO$_3{^-}$-N, NO$_2{^-}$-N, NH$_4{^+}$-N and EPS(Extracellular Polymeric Substances) in leachate, since biofilter had been steady-stately operated. The influent concentration of 10 ppm of TMA was removed to approximately 95% regardless of changing SV at 120 and 180 hr$^{-1}$, but it was lowered to 80 to 90% at SV 240 hr$^{-1}$. As influent concentration was gradually increased from 5 to 55 ppm, the removal efficiencies of TMA were initially high for 95% in the range of 5 to 10 ppm, but lowered to 80% for 10 to 30 ppm. As a part of kinetic study for TMA decomposition, V$_m$(maximum substrate removal rate) and $K_s$(substrate infinity coefficient) were 14.3 g$\cdot$m$^{-3}$$\cdot$h$^{-1}$ and 0.043 g$\cdot$m$^{-3}$, respectively while adapted period was shown in the range of 100 to 150 hr. Also, the EPS concentration was consistently observed from the leachate showing 100 to 200 ppm, which indicates that biofilm has been continuously formed and sustained throughout tire-chips packed reactor.

• Journal of the Korean Wood Science and Technology
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• v.34 no.4
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• pp.37-45
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• 2006

Recently, wood-framed houses has been built in the Korea for pension. Wood is good material for human healthy, while the construction lumbers are treated with preservative such as CCA (chromated copper arsenate), which contain some toxic elements for human body. However, if the waste woody biomass treated with various heavy metals, which has been collected from house construction or demolition, was fired in the field, and incinerated or landfilled after mass collection, such components will result in the toxic air pollutants in the burning or land fills, and spreaded into other areas. So the careful selection of wood and chemicals are required in advance for house construction, in particular, for environment-friendly housings. Therefore, this study was carried out to determine the content of toxic heavy metals in woody materials such as domestic hinoki and imported hemlock treated with CCA for housing materials, and the post-treated wood components such as organic fertilizer, sludge, dry-distilled charcoal and carbonized charcoal, to be returned finally into soil. The results are as follows. 1) The chemical analysis of toxic trace elements in various solid biomass required accurate control and management of laboratory environment, and reagents and water used, because of the error of data due to various foreign substances added in various processing and transporting steps. So a systematic analyzers was necessary to monitor the toxic pollutants of construction materials. 2) In particular, the biomass treated with industrial biological or thermal conditions such as sludge or charcoals was not fully dissolvable after third addition of $HNO_3$ and HF. 3) The natural woody materials such as organic fertilizer, sludge. and charcoals without any treatment of preservatives or heavy metal components were nontoxic in landfill because of the standard of organic fertilizers, even after thermal or biological treatments. 4) The CC A-treated wood for making the construction wood durable should not be landfilled, because of its higher contents of toxic metals than the criterion of organic fertilizer for agriculture or of natural environment. So the demolished waste should be treated separately from municipal wastes.

• Journal of Korean Society of Environmental Engineers
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• v.30 no.3
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• pp.278-285
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• 2008

This research was performed to evaluate the landfilling method of organic sludge from mix of pre-treated organic sludge (OS) and municipal solid waste(MSW). Organic sludges were dried, composted, and solidified as pre-treatment and the OS and MSW were mixed in ratios of 2 to 8 and 4 to 6. Approximately 1,800$\sim$2,500 L of landfill gas(LFG) was generated in the lysimeter with solidified-OS, which was higher than 1,150$\sim$1,650 L of the dried- and composted- ones. Maximum H$_2$S concentration was found in the following order : Composted-20(80 ppmv) > Composted-40(55 ppmv) > Dried-20(30 ppmv) > Dried-40 $\fallingdotseq$ Solidified-20 $\fallingdotseq$ Solidified-40 (20 ppmv). BOD$_5$ at initial leachate generation period was 38,000 mg/L for Composted-40, 28,000 mg/L for Dried-40, 26,000 mg/L for Dried-20, 21,000 mg/L for Composted-20 and Solidified-40, and Solidified-20 for 17,000 mg/L. In the final period of experiment, BOD$_5$ was low as 300$\sim$500 mg/L in the lysimeter with solidified-OS and MSW and showed 2,000$\sim$3,500 mg/L in dried- and composted- ones. As the results, landfilling by mix of solidified-OS and MSW was evaluated as the most appropriate method for biodegradable organics. Direct landfilling of OS is permitted for landfill site with CDM facility. Therefore, mixed landfilling of solidified-OS and MSW should be considered for much more LFG generation as methane.

• Analytical Science and Technology
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• v.8 no.1
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• pp.91-99
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• 1995

One of alternative conventional technologies used for treatment of livestock wastes is composting process, and recently some mechanical composting processes are being practiced. It is, however, recognized the composting process also has its own limitations such as longer time requirement, and difficulties to estimate the degree of decomposition, etc. The incomplete compost contains potentially harmful materials to crops and public health due to instabilized organic contents and pathogenic organisms. The purpose of this investigation is to develop an innovative system whereby anxious livestock wastes are thoroughly stabilized and disinfected. Thus the overall management scheme should meet the following requirements. 1. A system should be in a cost-effective and environmentally sound manner. 2. Sludges must be chemically stabilized and bacteriologically safe. 3. Odor-free by product should be applied to crop land. 4. Sludges are sources of fertilizer nutrients and/or soil amendments to enhance crop production. 5. And they can be used as potential pH adjusting agent of the acidified soils. Overall effectiveness of the developed system is experimentally tested to satisfy the preset criteria and requirements. Major experiments are divided into four categories: they are 1. chemical stability test, 2. optimal condition test of stabilization process, 3. bacteriological examination and disinfection tests, and 4. deodorization tests The stabilization process is consisted of the stabilizing reaction process and the drying process. Stabilized wastes is dried by both sun dryer and rotary dryer. It is shown that an additive dosage of about g/kg solid in wastes with a minimum of 5-minutes reaction would be necessary for effective stabilization reaction. The stabilization process is consisted of the stabilizing reaction process and drying process. Stabilized wastes are dried by both sun dryer and rotary dryer. It is shown that an additive dosage of about 300g/kg solid in wastes with a minimum of 5-minutes reaction would be necessary for effective stabilization reaction. In the stabilization reaction process, the pH of wastes is lowered from initial values of 12.3 to 8.6. High pH prevents odor production and kills pathogenic organisms. Organic matter contents in the stabilized wastes are about 50% and the sum of contents of fertilizer elements such as total nitrogen, $P_2O_5$ and $K_2O$ are about 5.3%. The livestock wastes that are stabilized chemically and hygienically can be used as a good soil conditioner and/or organic fertilizer.

• Journal of Korean Society of Environmental Engineers
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• v.28 no.3
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• pp.329-336
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• 2006

Iron manufacturing process involves production of various by-product including slag, sludge, sintering and EAF(Electric Arc furnace dust). Some of the by-products such as EAF and sintering dust are disposed of as waste due to their high heavy metal contents. It has been notice for many years that the EAF dust also contain about 65% of Fe(0) and Fe(II) and then the possible utilization of the iron. One possibility is to apply the EAF as a lining material in conjunction with clay or HDPE liners, in waste landfill. The probable reaction between the leachate containing toxic elements such as TCE, PCE dioxine and $Cr^{6+}$ is reduction of the toxic materials in corresponding to the oxidation of the reduced iron and therefore diminishing the toxicity of the leachate. It is, however, prerequisite to evaluate the leaching characteristics of the EAF dust before application. Amelioration of the leachate would be archived only when the level of toxic elements in the treated leachate is less than that of in the untreated leachate. Several leaching techniques were selected to cover different conditions and variable environments including time, pH and contact method. The testing methods include availability test, pH-stat test and continuous column test. Cr and Zn are potentially leachable elements among the trace metals. The pH of the EAF dust is highly alkaline, recording around 12 and Zn is unlikely to be leached under the condition. On the contrary Cr is more leachable under alkaline environment. However, the released Cr should be reduced to $Cr^{3+}$ and then removed as $Cr(OH)_3$. Removal of the Cr is observed in the column test and further study on the specific reaction of Cr and EAF dust is underway.

• Journal of Korean Society of Environmental Engineers
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• v.33 no.1
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• pp.47-53
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• 2011

$SF_6$ (Sulfur hexafluoride) possesses high GWP (Global Warming Potential) as sepcified by the IPCC (Intergonvernmental Panel of Climate Change). Recently, the recovery-separtion of $SF_6$ research area, including permeation properties studies using various membrane's materials and the practical operation of recovery-separtion using membrane of waste $SF_6$ gas is in the initial state. The separation efficiency of a single $SF_6$ and waste $SF_6$ mixture was evaluated using a PSF (polysulfone), PC (tetra-bromo polycarbonate) and PI (polyimide) hollow fiber membranes. According to the results of single gases permeation properties, PI membrane has the highest permselectivity of $N_2$ gas in $N_2/SF_6$ gas. Under the condition of P=0.5 MPa, the highest concentration of recovered $SF_6$ is 95.6 vol % in the separation experiment of $SF_6/N_2$ mixture gas by PC membrane. Under the operation pressure of P=0.3 MPa at a fixed retentate flow rate fixed of 150 cc/min, the maximum recovery efficiency of $SF_6$ is up to 97.8% by PSF membrane. From the results above, it is thought that the separation and recovery technique of $SF_6$ gas using membrane will be used as the representative eco-technology in the $SF_6$ gas treatment in the future.