• KSCE Journal of Civil and Environmental Engineering Research
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• v.36 no.4
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• pp.651-657
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• 2016

The purpose of this research was to examine the possibility on the recycling of foodwaste leachate as external carbon sources using microbubble. The following operating conditions were selected: pressurizing tank 3 bar, circulation flow rate 3.65 LPM, and air flow rate 0.3 LPM with batch type. Microbubble contact time of 18 hours is optimal time to satisfy the recycling of foodwaste leachate as external carbon sources with batch type. HRT 18 hours came up to standard for external carbon sources, except for T-P concentration with continuous type. Coagulants need to be used for removal of dissolved phosphorus concentration by more than 88.5% of the total phosphorus concentration. The VFA was influenced by the organic decomposition rate and the concentration in the aerobic condition. It was considered that the VFA was needed for selection the optimal HRT or the addition of acid fermentation process in order to meet recycling standard of foodwaste leachate.

• Resources Recycling
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• v.25 no.3
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• pp.37-42
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• 2016

Highly efficient and environmentally friendly mechanical process was developed for the higher recovery rate and productivity in the recycling of waste jelly-filled communication cables. Only the simplest mechanical method was designed and built for a continuous process, further proved experimentally along with the addition of several parts such as brush-type rollers and scrappers. In this process, the recovery rate and productivity were 98% and 55 Kg/hr respectively. This process is thought to be simple but highly advanced method for the commercialization of green process.

• Resources Recycling
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• v.7 no.1
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• pp.34-40
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• 1998

This shdy was invcsligated on reduction rate of EAF dust wth solid carbon cantents. The rate equation for reduction ofEAF dust was obtaincd in the tempcrahlrc range cot 910-108O"C, and the ratio of zinc removal and metallization raho of ironoxides to thc reaction time was also analysed. From the XRD analysis for slag residues '||'&'||'er reaction, the cxistcncc DI themixture of Akemmite[Ca2MgSi2O.] and SiO, was identified.ed.

• Journal of Environmental Science International
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• v.23 no.1
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• pp.97-104
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• 2014

The sludge flotation/thickening apparatus equipped a micro-bubble generating pump was used to investigate micro-bubble generating properties on operational parameters. We evaluated micro-bubble generating properties as results to be operated the apparatus by operational parameters which are pump discharge pressure, air/water ratio(A/W ratio), air flow rate, and water flow rate. Micro-bubble generating efficiencies in pumps without recycling flow and with 50% of recycling flow was found to be very efficient on optimum A/W ratio from 1.06 to 3.62% and optimum A/W ratio from 1.05 to 4.06%, respectively. In condition of 3.6% of A/W ratio, we showed that the apparatus could be generated 36,000 ppm of micro-bubble concentration to be optimum treatment efficiency in sludge thickening process.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 1996.06c
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• pp.500-510
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• 1996

A Direct injection -mixing total -flow -control sprayer was developed and evaluated . The system provided precise application rates and minimized operator exposure to chemicals as well as providing a possibility for recycling container so f unused chemicals that can causes environmental contamination. Chemicals were metered and injected proportionally to the diluent flow rate to provide constant concentrations. The main diluent flow was varied in response to changes in travel speed. Experimental variables of the sprayer were the control interval, the sensitivity of flow regulating valve, the tolerance of control object and the sensitivity of the injection pump system. The optimal performance of the flow control system was with an average response time of 8.5 sec at an absolute steady state of error of 0.067 L/min (0.8% of flow rate). The average response time of the injection rate was -0.53 sec and the coefficient of variation (CV) of concentration was 3.2%.

• Resources Recycling
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• v.22 no.3
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• pp.3-17
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• 2013

Recently, the importance of efficient resource management has been highlighted due to the uncertainty of its security. Korea has thus made an effort to improve the resource productivity in various fields such as the increase of recycling rate and the establishment of methodical resource management system. It is still necessary to draw the innovative improvement measure of national resource efficiency. This study derives major issues of recycling potential in the domestic industry by analyzing the current status of generation, treatment and recycling of industrial wastes in Korea. Futhermore, main tasks for promoting the improvement of national resource efficiency through the recycling of industrial wastes in Korea have been proposed based on the results of this study with the comparison of Japan's situation.

• Resources Recycling
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• v.6 no.4
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• pp.3-10
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• 1997

Electric are furnace dust (EAF dust) generated in steel production based on scrap melting is contained Zn and Fe about 25 and 30 percent by weight, respectively. From a metallurgical point of view, the dust could be regarded as a raw material for Zn and Fe source. To recover the Zn in the metal from EAF dust, many system are proposed such as Arc Plasma Furmace and Pb splasher method. In this study, to recover high purity Zn from Pb splasing alloy, Zn distillation is carried out at the temperature of 1123, 1173, 1223, 1273 K, the gas flow rate of 2.5, 5.0, 8.0 Ni/min and the distilling time of 10, 30, 60, 90 minutes. The main results obtained from this study are as follows:(1) The amount of evaporated Zn and its evaporating rate increased with increasing temperature, but purity of Zn decreased with increasing temperature. Optimum temperature range was found out to be between 1173∼1223K. (2) The amount of evaporated Zn and evaporation rate increased with increasing gas flow rate at a given temperature and distillation time. Gas flow rate has more influence over the amount of evaporated Zn and evaporation rate with increasing temperature.

• Journal of the Korea Organic Resources Recycling Association
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• v.29 no.3
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• pp.35-40
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• 2021

In order to investigate the degree of solubilization of sewage sludge using sono-activated persulfate(UV/PP), VSS reduction rate, solubilization rate and extracellular polymeric substances were measured. Ultrasonic(US) and alkali·ultrasonic method using sodium hydroxide(US/SH) were compared. Under the persulfate·ultrasonic conditions, the VSS reduction rate and the solubilization rate increased to 27.6% and 58.9%, respectively. TB-EPS as Carbohydrate and Protein were extracted by 770 mg/L and 2,162 mg/L. Compared to the other methods, US and US/SH, the VSS reduction rate and solubilization rate were higher. And also, according to the TB-EPS values, cell wall destruction was more efficient.

• Clean Technology
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• v.12 no.3
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• pp.113-127
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• 2006

Waste lubricating oil(WLO)s have been recycled as energy source through direct fuel in cement kilns and fossil power plants, or as fuel oils, or re-refined lubricating base oils. In our country, they have been recycled as low grade fuel oil through chemical treatment process. In 2003, extended producer responsibility (EPR) system was adopted from deposit system on sale of lubricating oils in order to promote their recycleing rate. However, our recycling rate of WLOs have been stagnant(below 70%) for last 5 years. And there has been no research work on recycling of WLOs as re-refined base oil until now in this country. Stabilization technology of thermally cracked oils to reduce tar and malodor and to improve their color for production of high grade fuel oil, and a novel process production of high grade re-refined lubricating base oil from WLOs have been developed and commercialized recently in Canada and U.S.A., respectively. Several countries like Australia, Italy, Germany and U.S.A., etc. are encouraging recycling companies to recycle WLOs as re-refined lubricating oil by giving greater subsidies or benefits compared to other recycling methods. They also adopt a policy to purchase re-refined lubricating oil preferentially in the federal or local governments and to recommend consumers to purchase it willingly. Based on the facts that several advanced countries have adopted a policy to recycle WLOs as re-refined base oil for saving of petroleum resource and reduction of environmental pollution, it is right time to be considered that our present policy for recycling of WLOs should be reevaluated and the new policy of their environmental-friendly and sustainable recycling should be established.

• Resources Recycling
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• v.16 no.6
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• pp.34-38
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• 2007

For recycling of tantalum from obsolete condenser, physical separations and chlorination of tantalum scraps with $Cl_2$ and $CCl_4$ were investigated. The recovery ratio of tantalum from obsolete condenser was 98% by using a multidisciplinary process of crushing by stamp mill, wet gravity separation by the shaking table, and air classification. In the chlorination reaction of non-oxidized Ta anode with $Cl_2$, the highest weight loss ratio is at least 60%, while in the chlorination reaction of Ta anode with $CCl_4$, the reaction rate for the oxidized Ta anode is faster than that of the non-oxidized Ta anode.