• Title/Summary/Keyword: mixed wastes

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Preliminary Study on Arsenic Speciation Changes Induced by Biodegradation of Organic Pollutants in the Soil Contaminated with Mixed Wastes (유기물분해에 따른 유류${\cdot}$중금속 복합오염토양내 비소화학종 변화의 기초연구)

  • 이상훈;천찬란;심지애
    • Economic and Environmental Geology
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    • v.36 no.5
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    • pp.349-356
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    • 2003
  • As industrial activities are growing, pollutants found in the contaminated land are getting diverse. Some contaminated areas are subject to mixed wastes containing both organic and inorganic wastes such as hydrocarbon and heavy metals. This study concerns with the influence of the degradation of organic pollutants on the coexisting heavy metals, expecially for As. As mainly exists as two different oxidation state; As(III) and As(V) and the conversion between the two chemical forms may be induced by organic degradation in the soil contaminated by mixed wastes. We operated microcosm in an anaerobic chamber for 60 days, using sandy loam. The soils in the microcosm are artificially contaminated both by tetradecane and As, with different combination of As(III) and As(V); As(III):As(V) 1:1, As(III) only and As(V) only. Although not systematic, ratio of As(III)/As(Total) increase slightly at the later stage of experiment. Considering complicated geochemical reactions involving oxidation/reduction of organic materials, Mn/Fe oxides and As, the findings in the study seem to indicate the degradation of the organics is connected with the As speciation. That is to say, the As(V) can be reduced to As(III) either by direct or indirect influence induced by the organic degradation. Although Fe and Mn are good oxidising agent for the oxidation of As(III) to As(V), organic degradation may have suppressed reductive dissolution of the Fe and Mn oxides, causing the organic pollutants to retard the oxidation of As(III) to As(V) until the organic degradation ceases. The possible influence of organic degradation on the As speciation implies that the As in mixed wastes may be have elevated toxicity and mobility by partial conversion from As(V) to As(III).

The method for the classification according to their kinds and the estimation of unit generation rate for promoting recycling of construction and demolition(c&d) debris (건설폐기물 재활용촉진을 위한 종류별 분류 및 발생원단위 산정 방안)

  • Lee, Hi Sun;Kim, Dong Sik
    • Journal of the Society of Disaster Information
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    • v.4 no.1
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    • pp.86-100
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    • 2008
  • It is needed to classify the kinds of construction and demolition(c&d) debris to 6 catagories of waste concrete, waste asphalt concrete, waste wood, scraps, combustible waste and incombustible waste in order to properly do a separate discharge and to estimate unit generation rate in construction site. Also, in this case, the unit treating cost for mixed wastes should be applied with the unit treating cost for combustible waste. The construction standard materials estimation data is used for basic data for estimating unit generation rate. The mixed wastes in this data should be classified to waste wood, combustible waste and incombustible waste, and their ratio is obtained by using the unit generation rate of Asia Pacific Environment and Management Institute and Seoul Metropolitan Development Institute. The waste amounts generated from newly-built construction can be obtained from multiplying the loss rate by the amount of materials used from construction standard estimation data. Also, those from dismantling construction can be obtained by subtracting waste amount generated during newly-built construction from total input amount of materials in newly-built construction. Those in two cases can be used in construction site. It can be used for estimating the amount generated and establishing the treating plan in the case of setting up the policy of waste management and doing the environment impact assessment.

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유기오염물의 분해에 의한 오염토양내 비소종 변화 영향

  • 천찬란;이상훈
    • Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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    • 2002.04a
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    • pp.347-350
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    • 2002
  • Arsenic speciation changes between As(V) and As(III) are subject to changes in accordance with redox conditions in the environment. It is common to find contaminated sites associated with mixed wastes including both organic pollutants and heavy metals. We conducted microcosm experiment under hypothesis that the co-disposed organic pollutants would influence on the arsenic forms and concentrations, via degradation of the organic pollutants and the consequent impact on the redox conditions in soil. Artificially contaminated soil samples were run for 40 days with control samples without artificial contamination. We noticed arsenic in the contaminated soil showed different behaviour compared with the arsenic in the control soil. The findings indicate degradation of organic pollutants in the contaminated soil influenced on the arsenic speciation and concentrations. A further work is needed to understand the process quantitatively. However, we could confirm that degradation of organic pollutants can influence on the abiotic processes associated with geochemical reactions in contaminated soil. Degradation of organic pollutants can increase the mobility and toxicity of arsenic in soil and sediment by changing redox conditions in the geological media and subsequently from As(V) to As(III).

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Studies on the Physico-chemical Properties of Vitrified Forms of the Low- and Intermediate-level Radioactive Waste (${\cdot}$저준위 방사성폐기물 유리고화체의 물리${\cdot}$화학적 특성 연구)

  • Kim, Cheon-Woo;Park, Byoung-Chul;Kim, Hyang-Mi;Kim, Tae-Wook;Choi, Kwan-Sik;Park, Jong-Kil;Shin, Sang-Woon;Song, Myung-Jae
    • Journal of the Korean Ceramic Society
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    • v.38 no.9
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    • pp.839-845
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    • 2001
  • In order to vitrify the Ion-Exchange Resin(IER), Dry Active Waste(DAW), and borate concentrate generated from the commercial nuclear facilities, the glass formulation study based on the their compositions was performed. Two glasses named as RG-1 and DG-1 were formulated as the candidate glasses for the vitrification of hte IER and DAW, respectively. A glass named as MG-1 was also formulated as a candidate glass for the vitrification of the mixed wastes containing the IER, DAW, and borate concentrate. The process parameters, product qualities, and economics were evaluated for the candidate glasses and confirmed experimentally for the some properties. The glass viscosity and electrical conductivity as the process parameters were in the desired ranges. the product qualities such as glass density, chemical durability, phase stability, etc. were satisfactory. In case of vitrifying the wastes using our developed glass formulation study, the volume reduction factors for the IER, DAW and mixed wastes were evaluated as 21, 89 and 75, respectively.

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Development of Screening Technology for Marine Waste Disposal (수산폐기물 전처리 용 스크린기술 개발)

  • Moon, Serng-Bae;Jun, Seung-Hwan;Jin, Gang-Gyoo
    • Journal of Navigation and Port Research
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    • v.33 no.1
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    • pp.57-63
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    • 2009
  • In order to effectively isolate the marine wastes with an effluent standard, the pretreatment process is required to isolate solid materials from the liquid-solid mixed wastes. The more effective the pretreatment becomes, the more processing capacity of posttreatment will be improved and process facilities will be downsized. In this paper, we suggested the vibrating reverse-slant screen, investigated the optimal vibration frequency and vibrator installation angle for the separation of the liquid solid mixed wastes. Several experiments for separation efficiency were conducted under the condition of various vibration frequency($35{\sim}60Hz$, 5Hz interval) and vibrator angle($0^{\circ}$, $30^{\circ}$, $45^{\circ}$, $90^{\circ}$) considering the crack of screen. The screen inclination angle is set up the gradient as $3^{\circ}{\sim}5^{\circ}$ through the preliminary experiments. Also, we made two types of screen(respectively rectangle and square screen). The separation device has shown the optimum efficiency at vibrator angle $0^{\circ}$ and vibration frequency 60Hz, and has no relation with the shape of screen. And the proposed technology is verified by comparing with quantity of suspended solids before and after filtration.

Recovery of Silver from the Spent Solution Generated from Electrochemical Oxidation of Radioactive Wastes (放射性 폐기물의 전기화학적 분해 폐액으로부터 銀의 回收)

  • 문제권;정종훈;오원진;이일희
    • Resources Recycling
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    • v.10 no.5
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    • pp.22-28
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    • 2001
  • Recovery of silver in the spent solution generated from MEO(Mediated Electrochemical Oxidation) process, which is a process to decompose radioactive organic mixed wastes at low temperature, was performed using chemical method. Silver nitrate in 5M nitric acid solution could be completely recovered as AgCl by using 1% excess of the stoichiometric HCl equivalents. Then, AgCl was transformed to Ag metal by reduction reaction with hydrogen peroxide under alkaline media. The optimum pH for the reduction to silver metal was found to be in the range of 12.8∼13.0.

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A Study for Unit Requirement and Material Classification of Construction Wastes for Improving Rate of Material Recycle (물질재활용률 향상을 위한 건설폐기물 성상별 분류 및 발생 원단위 산정에 관한 연구)

  • Kim, Byoung-Il;Song, Tae-Hyeob;Lee, Sea-Hyun
    • Journal of the Architectural Institute of Korea Structure & Construction
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    • v.29 no.12
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    • pp.81-88
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    • 2013
  • The quantity of construction wastes have been continuously increasing 178,120ton/day in 2010 compared to 148,489ton/day in 2004 such as concretes, asphalt concretes, metals, woods, synthetic resins, etc due to increased demolishing old apartments and expanding social facilities. Therefore, national efforts including department of environment, many universities and research centers have been studying to establish an effective system for reducing amount of waste, as well as improving rate of material recycle of construction wastes. One of the very best is to set up the exact basic unit of construction wastes for both new construction and demolition work. The purpose of this study was to classify construction wastes based on rate of material recycle and analyze basic unit of new construction and demolition work from analysis of a lot of data from construction company, as well as a field study. The types of construction wastes were classified into six for new construction and five for demolition work. The results for units of construction wastes showed that generation of concrete classes and mixed wastes was significantly greater than others specifically, apartment buildings. In conclusion, exacting separation and sorting efforts at on-site require to reduce waste amounts and activate rate of material recycle, as well as efforts on establishing systemized management.

A Study on the Properties of the Dual-mode Plasma Torch System for Melting the Non-conductive Waste (비전도성 폐기물 용융처리를 위한 혼합형 플라즈마토치 시스템 특성 연구)

  • Moon, Young-Pyo;Choi, Jang-Young
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.65 no.1
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    • pp.73-80
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    • 2016
  • The preliminary test for the dual mode plasma torch system was carried out to explore the operation properties in advance. The dual mode plasma torch system that is able to operate in transferred, non-transferred, or dual mode is very adequate for melting the mixed wastes including nonconductive materials such as concrete, asbestos, etc. since it exploits both the high efficiency of heat transfer to the melt in transferred mode and stable operation in non-transferred mode. Also, system operation including restarting is reliable and very easy. A stationary melter with a refractory structure was designed and manufactured considering the melting behavior of slags to minimize the refractory erosion. The power supply for the dual mode plasma torch system built with high power insulated gate bipolar transistor (IGBT) modules has functions for both current control and voltage control and is sufficient to suppress the harmonics during the operation of the plasma torch. The power supply provides two different voltages for transferred operation and non-transferred. It is confirmed that the operation voltage in transferred is always higher than non-transferred. The dual mode plasma torch system was successfully developed and is under operation for a melting experiment to optimize operation data.

Continuous Mediated Electrochemical Oxidation of Ethylene Glycol by Co(III)/Co(II) and Fe(III)/Fe(II) Redox Systems (Co(III)/Co(II) 및 Fe(III)/Fe(II) 산화환원계에 의한 에텔렌글리콜의 연속 매개전해 산화)

  • Kim, Ik-Seong;Park, Seung-Cho
    • Applied Chemistry for Engineering
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    • v.16 no.5
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    • pp.635-640
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    • 2005
  • Mediated electrochemical oxidation (MEO) is an aqueous process which oxidizes organics electrochemicallly at low temperatures and pressures. The useful process can be used to treat mixed wastes containing hazardous organics. This paper have studied MEO of ethylene glycol (EG) in nitric acids by Fe(III)/Fe(II) and Co(III)/Co(II) system. It investigated current density, supporting electrolyte concentration, hydraulic retention time, removal efficiency of EG by MEO. Removal efficiency of EG by MEO was superior in Co(III)/Co(II) redox system than Fe(III)/Fe(II) redox system, where MEO removal efficiency was 100 percent. In case of EG, the reactions were fast and good yields of carbon dioxide formation was observed.

Vitrification of Simulated Combustible Dry Active Wastes in a Pilot Facility

  • Yang, Kyung-Hwa;Park, Seung-Chul;Lee, Kyung-Ho;Hwang, Tae-Won;Maeng, Sung-Jun;Shin, Sang-Woon
    • Nuclear Engineering and Technology
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    • v.33 no.4
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    • pp.355-364
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    • 2001
  • In order to evaluate and finally optimize the vitrification condition for combustible dry active waste (DAW), dust and gas generation characteristics were investigated for PE, cellulose, and mixed waste Tests were conducted by varying the operation variables such as melter configuration, excess oxygen amount, and waste feeding rate. Results showed that dust generation characteristics were affected by the operation parameters and the melter's configuration is the dominant one. For all tested DAWs, dust generation was reduced by increasing the waste feeding rate and the excessive oxygen amount in the melter. Among waste types, dust amount was decreased by the order of mixed wastes, PE, and cellulose. Other parameters such as temperature variation and operation time have also affected the dust generation. The optimum condition for the DAW vitrification was determined as the melter's configuration equipped for minimizing the waste dispersion with 20 kg/h of waste feeding rate and 100% of excessive oxygen supply. CO gas concentration in the off-gas was immediately influenced by the combustion state in the melter, but showed similar trend as the dust generation. For the NOx production during the vitrification process, thermal NOx, which is generated from the Post Combustion Chamber (PCC), rather than fuel NOx was assumed to be dominant. The gas cleaning of efficiencies of the PCC, wet scrubber, and Selective Catalytic Reduction system (SCR) were found to be high enough to keep the concentration of pollutants (CO, NOx, SOx, HCI) in the stack below their relevant emission limits.

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