• Applied Chemistry for Engineering
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• v.17 no.4
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• pp.391-396
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• 2006

When radioactive wastewater was solidified treatment by cement, the drying rate of cement and the volume reduction ratio was decreased because of boric acid component in the wastewater. In order to supplement the demerit, effects of paraffin wax investigated in this study. Paraffin wax has a hydrophobic properties and a low affinity with inorganic materials. When the radioactive wastewater was tested by a small of wax, the compressive strength of solidified waste are decreased Therefore boric acid in radioactive wastewater are first treated by alkali salt and coated by the stearic acid. During the solidification step, The amount of paraffin wax addition get the result that the compressive strength of solidification with cement was the same as that with paraffin wax. The leaching properties of radioactive waste solidified was the same CFL (cumulative fraction leached), PR (penetration rate), effective diffusivity if paraffin wax content in solidified waste was 20% or 25%.

• Korean Journal of Environmental Agriculture
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• v.20 no.5
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• pp.317-324
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• 2001

Short-term effect of phosphogypsum on soil properties including acidification, salinity and metal availability were investigated under laboratory and field conditions. Phosphogypsum and mixtures of phosphogypsum and compost were added to soil and incubated in a laboratory condition with 15% moisture content. Phosphogypsum treatments were 2.5 and 5.0 g/kg soil and in the treatments of phosphogypsum and compost mixture 10 g of compost was added additionally. After the 30 days of incubation, an additional phosphogypsum and/or compost were added to the remaining soils at the same rates of the first treatments. pH, electrical conductivity, and available hazardous elements were measured periodically during the incubation. Field experiment was conducted in a plastic film house of mellon with four treatments of phosphogypsum and compost mixtures - 25+125, 50+125, 50+250 and 100+250 kg/165 $m^2$. pH, electrical conductivity, and hazardous elements in soil and total hazardous elements in leaf were measured. In the laboratory experiment, after 30 days of the first phosphogypsum application, soil pHs were lowered by 0.7-0.8 units. After the second treatment of phosphogypsum 0.2 units of additional acidification occurred. However, acidification was not observed in the soils treated with mixtures of phosphogypsum and compost. In the laboratory experiment, phosphogypsum treatments increased electrical conductivity very significantly. In field experiment, pH and electrical conductivity of soils treated with phosphogypsum were nearly the same as those of soil not treated with phosphogypsum. Since soil condition in the field study was an open system, the free acids and salts derived from phosphogypsum could be diffused down with water leaching through the soil profile and then any significant acidification or salt accumulation in the topsoil could not be observed. In both laboratory and field experiments, levels of available hazardous elements in soils treated with phosphogypsum were quite low and not different from the levels found in the control soil. Results obtained from this study suggest that application of phosphogypsum at appropriate rates on agricultural land appears of no concern in terms of acidity, salinity and hazardous element content of soil.

• Korean Journal of Soil Science and Fertilizer
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• v.46 no.4
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• pp.281-287
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• 2013

Due to its high salt content and poor physical properties in reclaimed tidal lands, it is important to ameliorate soil physical properties to improve the efficiency of desalination. The objective of this study was to evaluate the changes of soil properties at Saemangeum reclaimed tidal saline soil with various soil amendments. Field experiment was conducted at Saemangeum reclaimed tidal land in Korea and the dominant soil series was Munpo series (coarse loamy, mixed, nonacid, Mesic, Typic, Fluvaquents). Woodchips, crushed-stone, oyster shell, coal bottom ash, and rice hull were added as soil amendments and mixed into surface soil to improve soil physical properties. There was large variability in soil hardness, but oyster shell treatment was significantly lower soil hardness at surface layer. Soil hardness was not significantly different below 15 cm depth. Infiltration rate was also significantly greater at oyster shell treatment. This may be due to the leaching of Ca ions from oyster shell and improved soil properties. However, there was no statistical significant difference of the soil bulk density, moisture content, and porosity. Improved physical properties increased desalinization rate in soil and retarded the resalinization rate when evapotranspiration rate was high. Although soil salinity was significantly decreased with oyster shell amendment, soil pH was increased that should be made up as a soil amendment. Our results indicated that oyster shell application increased infiltration rate and improved soil hardness, and thus oyster shell could be used to improve soil salinity level at Saemangeum reclaimed tidal saline soil.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.8 no.1
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• pp.49-56
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• 2010

In the pyroprocessing of spent nuclear fuels, LiCl-KCl waste salt containing radioactive rare earth chlorides are generated. The radioactive rare earth oxides are recovered by co-oxidative precipitation of rare earth elements. The powder phase of rare eath oxide waste must be immobilized to produce a monolithic wasteform suitable for storage and ultimate disposal. The immobilization of these waste developed in this study involves a solid state sintering of the waste with host borosilicate glass and zinc titanate based ceramic matrix(ZIT). And the rare-earth monazite which synthesised by reaction of ammonium di-hydrogen phosphate with the rare earth oxides waste, were immobilzed with the borosilicate glass. It is shown that the developed ZIT ceramic wasteform is highly resistant the leaching process, high density and thermal conductivity.

• Journal of the Korean Ceramic Society
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• v.24 no.1
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• pp.77-85
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• 1987

Hardened cement paste is mainly affected by corrosion of sulphate and chlorine ions in sea water. In this investigation, many specimens were made with the cement clinker minerals such as C3S, C3A, C4AF and their mixture according to cement composition added various blending materials. After the specimens were immersed in 4% MgSO4 and MgCl2 solutions, the product of reaction, the microstructure of specimen and Ca+2 ion leached in the solution were studied. The formation of Ca(OH)2 in the specimen of C3S is reduced relatively by adding pozzolanic admixtures. The chlorine ion is easily diffuse into the C3S specimen and produced CaCl2 compound, and it makes the specimen porous by leaching out itself into the solution. The specimen of C3A, C4AF are broken down by expanding reaction of ettringite and gypsum compound produced in the MgSO4 solution. At a later period, the ettringite is transformed into gypsum and 5MgO.2Al2O3·15H2O. The C3A in the MgCl2 solution combines chlorine ion to form Friedel's salt and prevents the diffusion reaction of chlorine ion into the specimen. Granulated slag shows inferior effect on the resistance of the specimen in MgSO4 solution by forming ettringite and gypsum, but good result in MgCl2 solution. Pozzolanic materials, on the whole, offer noticable effect on the resistance of the specimen in both solutions.

• Magazine of the Korean Society of Agricultural Engineers
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• v.26 no.2
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• pp.85-96
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• 1984

石膏(改良劑)處理 및 用水管理方法에 依한 鹽害土壤의 除鹽效果를 分析하기 爲하여 浸出法(leaching method), 水洗法(rinsing method), 湛水法(ponding method ; 石膏混合處理 및 石膏非混合處理)에 依해서 3處理 3反復 4回連續抽出實驗이 遂行되었다. 나트륨減少量과 總鹽分減少率은 浸出法이 水洗法이나 湛水法에 比하여 더욱 效果的이었다. 石膏處理區의 除鹽率이 石膏無處理區의 除鹽率보다 比較的 높았으며 石膏處理區(에이커當 2톤 石膏處理區 및 4톤 石膏處理區) 사이에는 別差異가 없었다. 除鹽實驗後 나트륨吸着度(SAR)는 浸出法과 水洗法을 使用한 石膏處理區에서 $10(meq/l)^{1/2}$以下로 減少되었다. 連續抽出의 境遇 SAR은 水洗法을 使用한 石膏處理法에서 單位土壤깊이當 供給用水깊이의 比率($D_w/D_s$)이 3.0以上으로 될때 $10(meq/l)^{1/2}$以下로 減少되었고 浸出法을 使用한 石膏處理區에서는 $D_w/D_s$가 1.5以上일때 $10(meq/l)^{1/2}$以下로 減少되었다. 除鹽實驗後 飽和抽出液의 電氣傳導度(EC)는 全實驗區에서 4mmhos/cm以下로 減少되었다. 連續抽出의 境遇 EC는 水洗法을 使用한 石膏處理區에서 $D_w/D_s$가 3.0以上일때 4mmhos/cm以下로 減少되었고浸出法을 使用한 石膏處理區에서는 $D_w/D_s$가 1.5以上으로 될때 4mmhos/cm以下로 減少되었다. 排水가 比較的 良好한 土壤의 置換性나트륨百分率(ESP)은 除鹽實驗後 浸出法과 水洗法을 使用한 石膏處理區에서 15%以下로 減少되었고 排水가 不良한 土壤의 ESP는 水洗法을 使用한 石膏處理區에서 15%以下로 減少되었다. 나트륨吸着度, 電氣傳導度, 置換性나트륨百分率 等을 勘案하여 볼때 本鹽害土壤은 石膏處理浸出法 또는 石膏處理水洗法에 依하여 比較的 쉽게 改良될 수 있다고 判斷된다. 除鹽效果 및 改良劑費用等을 考慮하여 보면 排水가 比較적 良好한 鹽害土壤의 境遇 에이커當 2톤 石膏處理 浸出法이 效果的인 方法으로 보이며 排水가 不良한 鹽害土壤의 境遇에는 에이커當 2톤 石膏處理 水洗法이 比較的 效率的인 除鹽 方法이라고 思科된다. 排水가 不良한 鹽害土壤의 浸透率을 增加시키고 除鹽을 促進시키기 爲해서는 石膏等과 같은 改良劑의 供給이 必要한 것으로 看做되며 現場條件下에서도 表土層土壤의 除鹽을 爲해서는 石膏處理浸出法과 石膏處理水洗法이 效率的인 方法으로 期待된다.

• Resources Recycling
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• v.17 no.1
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• pp.38-42
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• 2008

This study was carried out to investigate the solubility of vanadium in ammoniacal solution and precipitation of $NH_4VO_3$ as a function of temperature and addition of ammonia salt. Higher solution temperature is required to get high solubility of vanadium and the vanadium concentration of solution was 16.8g/L at $90^{\circ}C$ with the solution of 20 g/L $(NH_4)_2CO_3$ and 2.5M $NH_4OH$. From this solution, vanadium could be precipitated up to 99.8% with adding 20 g/L $NH_4Cl$, 72 hours settling time at $25^{\circ}C$.

• Korean Journal of Soil Science and Fertilizer
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• v.39 no.2
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• pp.65-72
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• 2006

Objective of this research was to remove the accumulated salts in the plastic film house soils by installing the perforated PVC (${\phi}10cm$) underdrainage pipes at 50 cm depth of soils with cultivating vegetables. Efficiency of the underdrainage pipes was assessed based on the changes of soil chemical properties such as pH, EC, and cations, and growth and yield parameters of the vegetables between the two treatments; the control and the underdrainage pipe treatments. The EC of the underdrainage pipes installed soils after two growing seasons were in the ranges of $1.42-2.88dS\;m^{-1}$ but those of the control were in the ranges of $3.86-4.53dS\;m^{-1}$, indication the underdrainage pipes effectively removed the accumulated salts in soils. The pHs of the control soils and the underdrainage pipe installed soil were in the ranges of 7.2-7.5 and 6.9-7.3, respectively. There was a significant correlation between pH and cation exchange capacity (CEC) of the soils ($CEC=17.107{\times}pH-106.2$, $r^2=0.759$, P < 0.05). The ECs of the soils at different depths were compared between the two treatments after cultivating vegetables with lettuce-lettuce-garland chrysanthemum rotation systems. The ECs of the control soils at depths of 0-10, 10-20, 20-30, 30-40, and 40-50 cm were 3.45, 3.47, 3.03, 2.03, and $2.28dS\;m^{-1}$, respectively, with decreasing with soil depths. On the other hand, the respective ECs of the underdrainage pipes installed soils were 2.43, 2.52, 2.28, 4.00, and $4.23dS\;m^{-1}$ with increasing with soil depths. This might be derived from the salts moved downward with the draining water into the subsoil. The order of cations moved downward was Mg > Ca > K, based on the ratios of cations at specific depth over those at the surface soil. The survival rates of lettuce after 15 days of transplanting in the underdrainage pipe installed soils were 98.2% as compared to 86.6% of the control. The underdrainage pipe treatment also increased the diameter of the lettuce stalk from 12.9mm of the control to 13.7mm. Overall results demonstrated that the installment of the underdrainage pipes in the subsoils of the salt accumulated plastic film house soil effectively removed the salts by leaching downward,resulting in lowering soil EC and enhancing the growth and yield of vegetables.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.10 no.1
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• pp.45-53
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• 2012

The metal chloride wastes from a pyrochemical process to recover uranium and transuranic elements has been considered as a problematic waste difficult to apply to a conventional solidification method due to the high volatility and low compatibility with silicate glass. In this study, a dechlorination approach to treat LiCl-KCl waste for final disposal was adapted. In this study, a $SiO_2-Al_2O_3-P_2O_5$ (SAP) inorganic composite as a dechlorination agent was prepared by a conventional sol-gel process. By using a series of SAPs, the dechlorination behavior and consolidation of reaction products were investigated. Different from LiCl waste, the dechlorination reaction occurred mainly at two temperature ranges. The thermogravimetric test indicated that the first reaction range was about $400^{\circ}C$ for LiCl and the second was about $700^{\circ}C$ for KCl. The SAP 1071 (Si/Al/P=1/0.75/1 in molar) was found to be the most favorable SAP as a dechlorination agent under given conditions. The consolidation test revealed that the bulk shape and the densification of consolidated forms depended on the SAP/Salt ratios. The leaching test by PCT-A method was performed to evaluate the durability of consolidated forms. This study provided the basic information on the dechlorination approach. Based on the experimental results, the dechlorination method using a $SiO_2-Al_2O_3-P_2O_5$ (SAP) could be considered as one of alternatives for the immobilization of waste salt.

• Korean Journal of Soil Science and Fertilizer
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• v.26 no.3
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• pp.172-180
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• 1993

Chemical properties of the soils were surveyed in the field of vinyl houses concentrated in the area of Bunpyong-dong and Shinchon-dong of Cheongju, Chilgeum-dong of Chungju and Gageum-myeon of Jungweon-gun. Chungcheongbuk-do province. 1. Content of chemical component of the soil in the vinyl house was higher than in open field. In more than half of the vinyl house soils surveyed, electric conductivity was more than 4.0 mmhos/cm and available phosphate was more than 1,000ppm. 2. Contents of availble phosphate and exchangeable potassium were increased with years of cultivation and their content of accumulation in soil were in the order of Bunpyong-dong>Shinchon-dong>Gageum-myeon>Chilgeum-dong. While their mobility was comparatively low. 3. $NO_3$-N content was remarkably higher in vinyl house soil and the older in cultivation made $NO_3$-N content higher same as the case of available phosphate content. However easy leaching of $NO_3$-N through soil profile is expected due to the fact that $NO_3$-N content was rapidly decreased by removal of polyethylene film cover from the frame of house after harvest of crops. 4. It is a tendency that various chemical contents of vinyl house soils wer higher in 1992 than in 1988~1990, especially much higher from the area of Bunpyong-dong and Shinchon-dong of Cheongju. 5. Salt accumulation in vinyl house soil has been increased with continuing cultivation. Therefore amount of fertilizer application should be controlled in order to avoid salt toxicity, quality deterioration for crop and salt contamination of ground water.