• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.12 no.1
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• pp.1-6
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• 2014

A large amount of acidic waste solution is generated from the practical electrokinetic decontamination equipments for the remediation of soil contaminated with uranium. After filtration of uranium hydroxides formed by adding CaO into the waste solution, the filtrate was recycled in order to reduce the volume of waste solution. However, when the filtrate was used in an electrokinetic equipment, the low permeability of the filtrate from anode cell to cathode cell due to a high concentration of calcium made several problems such as the weakening of a fabric tamis, the corrosion of electric wire and the adhension of metallic oxides to the surface of cathode electrode. To solve these problems, sulfuric acid was added into the filtrate and calcium in the solution was removed as $CaSO_4$ precipitate. A decontamination test using a small electrokinetic equipment for 20 days indicated that Ca-removed waste solution decreased uranium concentration of the waste soil to 0.35 Bq/g, which is a similar to a decontamination result obtained by distilled water.

• Land and Housing Review
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• v.1 no.1
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• pp.35-42
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• 2010

Most of the dredged sand generated from the sewage pipe maintenance project and the government's four-river project are disposed depending on abandonment and filling-up. This is caused by the lack of related recycling technology using dredged sand appropriately and high absorption rate and micro-particles of dredged sand producted from existing sand production system. Thus, this study carried out a quality assessment for the dredged sand produced through the optimum washing and sorting system supplementing problems of existing dredged sand production system as a part of research to examine performance of removing micro-particles and foreign substances. As a result of the assessment, the dredged sand produced through the cleaning and sorting system showed a wide quality improvement effect in absorption rate, 0.08 mm sieve pass amount, clay lump volume and organic impurity content, and it turned out to satisfy both the quality standards of this study, KS F 2573(recycled aggregate for concrete) and KS F 2526(aggregate for concrete) so it could be confirmed that it would be able to be used as an aggregate for concrete in the future.

• Resources Recycling
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• v.21 no.1
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• pp.17-29
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• 2012

potential assessment of converting closed non sanitary landfills into sustainable landfill through the reclamation works(= landfill mining project) of illegal landfill discovered in land development site using Sustainable Landfill Reclamation system(SLR-system) was investigated. The SLR system had treatment capacity of 91.4 $m^3/hr$ (130.61 ton/hr) in condition of 28.0% of water content. Recovery ratio and purity of sorted soil were 98.9% and 99.66%, respectively. Sorted combustibles were 91.8% and 92.0%, respectively. Especially, high heating value (HHV) and low heating value(LHV) of combustibles were 4,282kcal/kg and 3,636 kcal/kg, respectively, in considering the energy content and recovery ratio of combustibles. Therefore, combustibles separated from landfill site have higher value than Fluff RDF standard value(3,500kcal/kg) of MOE. RDF can be produced with combustibles by 84.43%. Averaged size and organic foreign matter content of the sorted soil were less than 035mm and 0.31 %(VN), respectively. In addition, concentration of all contents of hazardous matters containing soils met safety standards. Therefore, it is possible to be recycled as refilling and cover materials to rebuild Sustainable landfills by 98.42%.

• Journal of the Korean Society of Hazard Mitigation
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• v.11 no.3
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• pp.97-103
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• 2011

In this research, a small-scaled laboratory test and FEM analysis have been carried out to evaluate the feasibility of field construction with couple of recycled materials, such as in-situ soil, water-treatment sludge, and crumb rubbers. A static loading, which simulates the real traffic load, was adopted in lab test. The test was carried out, according to simulated field construction stages, such as excavation, bedding materials and pipe installation, placing and curing of controlled low strength materials, and simulated traffic loading. Couple of measuring instruments were adopted. The maximum vertical and horizontal deformations were 0.83% and 1.09%, during placing the CLSM. The measured vertical and horizontal deformations with curing time were 0.603mm and 0.676mm, respectively. The reduction effect of vertical and lateral earth pressure was relatively big. Also, FEM analysis was carried out to get the deformation, earth pressure and strain of PVC with different Controlled Low Strength Materials(CLSM) materials.

• Korean Journal of Soil Science and Fertilizer
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• v.38 no.2
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• pp.72-77
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• 2005

This study was performed to examine the effects of aluminum addition and recycle of NaOH waste solution on CEC and crystallinity of zeolite synthesized from fly ash. The added aluminum was used as the source of zeolite framework in zeolitization of fly ash. CEC and crystallinity of Na-P1 zeolite synthesized with aluminum addition were increased from 285 to $365cmol_c\;kg^{-1}$ and from 44.3 to 57.1% compared to that of simple hydrothermal treatment, respectively. The recycled NaOH solution did not affect the CEC of reaction products, though the crystallinity was decreased a little. Therefore, the additional supply of aluminum could improve the quality of zeolite synthesized from fly ash and the recycle of NaOH during zeolite synthesis can save the chemical without any adverse effects in the quality of synthesized seolite.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.4
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• pp.606-612
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• 2019

The main causes of subsidence and sinkholes in the lower part of urban roads are sewage line foundation and inadequate compaction of backfill material. This leads to many problems, such as the breakage of joints in sewer pipes, poor connection, pipe breakage, and cracks. To solve this problem, the support factor related to the sewer foundation and the safety factor according to the excavation depth were evaluated. For the foundation of rigidity tolerance, crushed stone foundation, and abandoned concrete foundation, a recently newly developed site assembly-type lightweight plastic foundation were used. Backfill materials were applied on site (sandy soil and clayey soil) and fluid backfill was recycled onsite. To evaluate the depth of excavation and the safety factor of each sewer pipe foundation, the design load considering the load factor and the support factor was evaluated. The support coefficients were 0.377 for a crushed stone foundation, 0.243 and 0.220 for an abandoned concrete foundation ($180^{\circ}$ and $120^{\circ}$), and 0.231 for a lightweight plastic foundation and fluid backfill. Overall, the safety factor was low when using the crushed stone foundation, and the safety rate was the highest when the foreclosed concrete foundation ($180^{\circ}$) was used. In addition, when the combination of lightweight plastic and fluid backfill materials was used, the safety factor was higher than that of abandoned concrete foundation ($120^{\circ}$), which means that the newly developed lightweight plastic foundation can be used as another alternative base of a steel pipe.

• Korean Journal of Environmental Agriculture
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• v.41 no.4
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• pp.236-244
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• 2022

BACKGROUND: Liquid fertilizers can provide nutrients to crops effectively and quickly. Amino acid liquid fertilizers produced by decomposing the residues of rendered livestock carcasses are expected to be effective in improving the productivity and quality of crops. METHODS AND RESULTS: The treatment conditions for maize cultivation were control (Cn), inorganic fertilizer (IF), inorganic fertilizer and rendering residue liquid fertilizer (IF+RALF), compost (CP), compost and rendering residue liquid fertilizer (CP+RALF). Crop productivity, sugar content, and nutrient uptake were investigated after maize harvest in the field applied with liquid fertilizers. Maize yields ranged from 87.6-158 g/plant, and the yield increased by 7.9% and 12.9% in IF+RALF IF+RALF and CP+RALF than in IF and CP, respectively. The maize sugar content increased in the range of 0.1-0.5 brix % by rendering residue liquid fertilizer (RALF) fertilization, and the sugar content was the highest in CP+RALF. There was no significant change in soil chemical properties of the soil due to liquid fertilizer treatment. CONCLUSION(S): RALF increased yield and sugar content in maize cultivation, and fertilization with organic fertilizers was more effective for maize cultivation than inorganic fertilizers. Residues of rendered livestock carcass can be recycled as amino acid fertilizers, which can be effectively used for crop production and quality improvement.

• Applied Chemistry for Engineering
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• v.21 no.2
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• pp.217-223
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• 2010

In general, fiber-reinforced plastics (FRP) wastes are simply buried or burned. Landfill brings about a permanent contamination of soil due to the inability of FRP to decompose and incineration causes an issue of generating toxic gases and dusts. There have been several ways to treat the FRP wastes such as landfill, incineration, chemical recycling, material recycling and the utilization of energy from combustion. Most methods excluding material recycling are known to have critical limitations in economic, technical and environmental manners. However it is known that material recycling is most desirable among the methods handling FRP wastes. In this study, to investigate the purpose of feasibility of material recycling, various bulk molding compound (BMC) specimens were prepared with the various contents of unsaturated polyester resin binder (25, 30, 35 wt%) and the various replacement ratios of FRP wastes powder (0, 25, 50, 75, 100 wt%) substituted for filler. To evaluate the physical properties BMC specimens, various tests such as tensile strength, flexural strength, impact strength, hot water resistance and SEM imaging were conducted. As a results, mechanical strengths decreased with an increase of replacement ratio of FRP waste powder and physical properties of BMC specimens were deteriorated in the hot water resistance. The fluidity of BMC with more than 50 wt% of the replacement ratio of FRP wastes powder decreased remarkably, causing a problem in the BMC composite.

• Journal of the Korea institute for structural maintenance and inspection
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• v.17 no.3
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• pp.136-144
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• 2013

In this study, in order to establish a plan that will enable safe use of renewable resources such as diverse industrial by-products and urban recycled materials, we conducted experiments that focused on flow, bleeding, compressive strength and environmental pollution evaluation to evaluate the material properties of low strength concrete using BFS and SS. In the case of low strength concrete using BFS and SS, blending of at least BFS 6000 within a 30% range regardless of the type of sand used was found to be the most effective approach for improving the workability by securing the minimum unit quantity of water, restraining the bleeding ratio and establishing compressive strength by taking account of the applicability at the work site. In particular, in view of the efficient use of SS, the optimal mixing condition was found to be the mixing of BFS 8000 with in the 30% range, not only for improving the workability restraining the bleeding ratio and establishing the compressive strength but also for application to the work site. Further, the results of tests on hazardous substance content and those of elution tests conducted on soil cement using SS indicated that all values satisfied the environmental standards without any harmful effects on the surrounding environment.

• The Journal of Engineering Geology
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• v.27 no.3
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• pp.245-253
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• 2017

Vietnam CFBC fly ash has high CaO content and can be used as a solidification agent for soft ground improvement. However, most fly ash is treated as landfill or waste. In order to utilize fly ash as a solidification agent for soil improvement, the characteristics of fly ash must be accurately determined. In this study, laboratory tests were conducted on fly ash from four CFBC power plants to evaluate the utility of Vietnam fly ash as a solidification agent. As a result of analyzing the physical properties, it was analyzed that all four samples were suitable as material for solidification agent and have suitable particle size for the improvement of soft ground. As a result of analysis of chemical characteristics, it was analyzed that the fly ash of one place could be used as a solidification agent because of the high content of free-CaO. The remaining three fly ash was not suitable for use as a solidification agent due to low Free-CaO content. However, it has a chemical composition similar to that of general fly ash in Korea, so it can be recycled in various ways.