• 한국지구물리탐사학회:학술대회논문집
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• 2003.11a
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• pp.573-580
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• 2003

In Taiwan there are 21 Municipal Solid Waste Incinerators (MSWI) built to treat 80% of the MSW nationwide. Approximately 2,000 tons of incineration ashes of municipal waste contain reaction ash and fly ash (3:1 by weight)will be produced daily, and this may cause a serious waste problem. According to EPA regulations, reaction ash and fly ash produced after incineration should be properly treated. Landfill capacity barely meets the general demands. More efficient actions should be planned and taken. The study found 'reclamation' should be the optimal solution to this problem. Only limited research and previous successful experiences are available among other countries. An incinerator in Northern Taiwan is chosen for this study to make environmental bricks from the reaction ash and fly ash. From the previous tests, the results of strength test were measured. From the previous test results, the fly ash products have not reached the desired strength; hence, reaction ash is chosen for further pilot study. In the experiment, incineration ashes, cement and gravel are mixed in the ratio of 1:1:1(by weight), to ground concretization aggregate and pelletization aggregate, the concrete products made from the aggregates were of the strength of 108 $kgf/cm^2$ and 142 $kgf/cm^2$ individually. For the purpose of making nonstructural walls which met the State Building Standards. In the study, 50 tons of concrete products was yielded from aggregate and environmental bricks. Further observation and supervision are recommended to ascertain the resource recycling and reclamation. EPA has planned to build three 'Recycling Plants' in northern, middle and southern Taiwan to develop efficient techniques to produce concrete products, sub-base course, soundproofing wall, gravel, artificial fishing reefs, tiles, drainage, bricks and etc. This experiment of the demonstrative plant solves the problem of the incineration ashes and opens another opportunity to reclaim them.

• Advances in environmental research
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• v.5 no.2
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• pp.125-140
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• 2016

The paper is focused on the economic analysis of two hydrometallurgical processes for recovery of yttrium and other rare earth elements (REEs) from fluorescent phosphors of spent lamps. The first process includes leaching with sulphuric acid and precipitation of a mixture of oxalates by oxalic acid, the second one includes leaching with sulphuric acid, solvent extraction with D2EHPA, stripping by acid and recovery of yttrium and traces of other rare earths (REs) by precipitation with oxalic acid. In both cases the REEs were recovered as oxides by calcination of the oxalate salts. The economic analysis was estimated considering the real capacity of the HydroWEEE mobile's plant ($420kg\;batch^{-1}$). For the first flow-sheet the cost of recycling comes to $4.0{\euro}kg^{-1}$, while the revenue from the end-product is around $5.40{\euro}kg^{-1}$. The second process is not profitable, as well as the first one, taking into account the composition of the final oxides: the cost of recycling comes to $5.2{\euro}kg^{-1}$, while the revenue from the end-product is around $3.56{\euro}kg^{-1}$. The process becomes profitable if the final RE oxide mixture is sold for nearly $50{\euro}kg^{-1}$, a value rather far from the current market prices but not so unlikely since could be achieved in the incoming years, considering the significant fluctuations of the Res' market.

• Journal of the Korea Organic Resources Recycling Association
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• v.10 no.3
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• pp.110-116
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• 2002

The aim of this study was to analyze food waste treatment cost and to estimate effect of by-product, such as wastewater and foreign materials, on amount cost. In cost analysis, man power and facility capacity are fixed, whereas operation cost, by-product treatment and et, al. are varied by treatment methods. The rate of by-product treatment cost in amount cost are between 5% and 39%. The methods which consume large electric power or generate much wastewater showed higher rate of by-product treatment cost in range of 14 to 39%. On the other hand, the methods which have simple process showed lower rate in range of 5 to 11%. Thus, this study recommend that by-products should be treated in sewage treatment facilities or landfill sites to prevent illegal disposal of by-products or to reduce burden of by-product from private sectors.

• Journal of the Korea Organic Resources Recycling Association
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• v.7 no.2
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• pp.93-104
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• 1999

Existing composting system was improved to have a high performance for organic degradation, deodorization and energy reduction. Compared with conventional devices, this developed system uses the heat recovered from platinum catalytic tower by three times heat exchange in which 65% of exhaust gas was recirculated. Evaporation of water was made easy by maintaining negative pressure in entire system. It was possible for reaction to be maintained steadily by microorganism agent. The optimum mixing volume ratio of garbage to sawdust was 15:1 contrary to 20:1 in conventional one. Moreover, aerobic condition was maintained efficiently. Effects obtained by using a inner circulation system were as follows. It was possible to reduce the ammonia causing offensive odor and verified that consumption of electricity cut down to 1/3 with reduction of exhaust gas inflowing. According to this inner circulation, the optimum air flow was $0.44m^3$ to 100kg treatment capacity. The electricity consumption was changed in proportion to inflowing air volume.

• Resources Recycling
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• v.27 no.3
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• pp.39-47
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• 2018

According to Vietnam government establishes additional coal-fired power plants to secure generation capacity, emission of ashes is accelerating and processing them is urgent issue. This study targeted utilize fly ashes that occurred in circulating fluidized bed combusion (CFBC) power plant to use ground solidification materials. CFBC fly ashes are used to make solidification with ground granulated blast furnace slag (GGBFS), gypsum and cement. Then produced specimens by mixing with soft ground soil to confirm mixing effect of fly ash in solidification. As a result it was possible to find mixture design that is satisfied 3 MPa compressive strength in age 28 days and reduce weight loss rate over 50% in acid immersion test than plain specimens that using only ordinary portland cement.

• Journal of the Korea Organic Resources Recycling Association
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• v.25 no.2
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• pp.27-31
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• 2017

This study was performed to estimate bubble dissolution rate by change of hydraulic pressure according to increase of water depth. Experimental results showed that airflow rate was decreased by increase of hydraulic pressure. Because the force which acts on outlet of nozzle was increased by increase of hydraulic pressure. Mass-transfer coefficient decreased with decreasing airflow rate and increasing effective volume due to increase of hydraulic pressure as water depth increased. On the contrary, as the water depth increased, the bubble dissolution rate was increased because longer residence time of microbubble which was generated by ejector type microbubble generator. However it was thought that if water depth for capacity of ejector type microbubble generator is excessively increasing, bubble dissolution rate would be reduced due to low airflow rate and mass-transfer coefficient. Therefore, it is importance to consider the water depth when operating ejector type microbubble generator.

• Applied Chemistry for Engineering
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• v.28 no.5
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• pp.521-528
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• 2017

To find a recycling method for waste liquid crystal display (LCD) panel glasses, we investigated the synthesis process of zeolite with an ion exchange ability by hydrothermal reaction using waste LCD panel glass as a raw material. It was shown that the waste LCD panel glass can be used as a raw material for the production of zeolites having the ion exchange ability. Following conditions for the synthesis of the zeolite with an ion exchange ability were required : the molar ratio of Si to Al components of the waste LCD glass needs to be 2.0 to 2.8, and the temperature of $100^{\circ}C$ and reaction time of 12 hours are needed for the hydrothermal reaction. Based on the required conditions previously mentioned, the A type zeolite was synthesized when the molar ratio of the Si to Al component was 2.0, and the P type zeolite was produced when the molar ratio was 2.8. The type A zeolite synthesized by using the waste LCD panel glass showed a good ion exchange ability and heavy metal adsorption ability. Also, an excellent ion exchange capacity was observed as the crystal phase grows stably in a cubic phase.

• Journal of the Korea Organic Resources Recycling Association
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• v.11 no.1
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• pp.92-96
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• 2003

The on-site sewage sludge vermicomposting equipment was designed and evaluated on the batch and continuous tests. The vermicomposting equipment was designed to consider the mechanization as well as automation. In terms of performance evaluation of equipment with continuous experiments, the highest treatment rate was found in the condition of 5mm in particle size and 10mm in e feeding height. Also, 20~25kg of earthworm per 50kg of sewage sludge was the most appropriate density of earthworm. In addition, the most effective separation of cast was found when the earthworm breeding box height was 80cm. The performance evaluation on equipment allowed the establishment of earthworm composting capacity of 2ton per a day with a size of $5{\times}3{\times}1m$ and the automatic control devices.

• Resources Recycling
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• v.16 no.6
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• pp.46-51
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• 2007

This study aimed at developing high-efficiency RDF(refuse derived fuels) fuel in order to use RDF energy rationally and to recycle industrial product. As most studies in this area are concentrated in large combustion apparatuses such as kilns, but this study was focused on the small-sized heating systems, applying them directly to grate type boiler which has a heating capacity of $66{\sim}132m^2$. The different kinds of fuel are experimented including RDF. Coke and Waste Tire. First, for this, we experimented and analyzed RDF to see the change in its mass and heating value. Also, four kinds of exhaust gas are sampled by gas analyzer including CO, $CO_2$, NO and $NO_2$ at different temperature. As a result, the levels of CO concentration of RDF are higher than these of coke and waste tire. But, the levels of NO, $CO_2$ and $SO_2$ concentration of RDF and coke were lower then the levels when waste tire is burned.

• Resources Recycling
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• v.22 no.5
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• pp.3-12
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• 2013

It is necessary to manage risk of metals which are has rigid supply structures and expected demand expansion, considering to industry structure and resource securing capacity of each country. Countries conducted various criticality analyses and selected mainly rare metals as critical materials(or Critical metals or Critical raw materials). This study examined cases of metals risk evaluation and management which are based on technology changes and imbalance supply-demand. EU and U.S.A evaluated risk on metals needed as supply expansion of renewable energy. Japan forecasted demand of rare metals needed in Japan's growth engine industry. U.K analyzed criticality of metals, considering environmental burden occurred from mining to refining. Critical materials has features such as weak price signal, inelastic supply structure, demand volatility in technology change.