• Journal of the Korea Organic Resources Recycling Association
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• v.16 no.3
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• pp.65-74
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• 2008

In this study, the composition and physico-chemical characteristics of municipal solid waste (MWS) which was treated in four different area were investigated. It is necessary to measure the characteristics of MSW to build a waste treatment and Refuse Derived Fuel (RDF) facility, the data-base and total managing of the landfill. It was found that the average density of solid wastes is in the range of $78.15-199.8kg/m^3$. This MSW was composed of 8.87% of food wastes, 38.8% of papers, 34.12% of plastics & vinyls, 7.16% of textiles, 0.96% of wood, 1.3% of rubber & leathers and others, respectively. Most of MSW are composed of food, paper and plastic waste and more than 94% was combustible waste. For three components, moisture is 17.38%, combustible component is 69.03% and ash is 6.24%. The chemical element has the high order of carbon, oxygen, hydrogen on the dry basis of wastes. And the low heating value of the MSW which is measured by calorimeter is calculated as 2973.8 kcal/kg and high heating value of the MSW is calculated as 5209.94 kcal/kg.

• Korean Chemical Engineering Research
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• v.47 no.5
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• pp.630-638
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• 2009

A computational fluid dynamics(CFD) model is developed and validated with on-site experiments for a urea-based SNCR(selective non-catalytic reduction) process to reduce the nitrogen oxides($NO_x$) in a municipal incinerator. The three-dimensional turbulent reacting flow CFD model having a seven global reaction mechanism under the condition of low CO concentration and 12% excess air and droplet evaporation is used for fluid dynamics simulation of the SNCR process installed in the incinerator. In this SNCR process, urea solution and atomizing air were injected into the secondary combustor, using one front nozzle and two side nozzles. The exit temperature($980^{\circ}C$) of simulation has the same value as in situ experiment one. The $NO_x$ reduction efficiencies of 57% and 59% are obtained from the experiment and CFD simulation, respectively at NSR=1.8(normalized stoichiometric ratio) for the equal flow rate ratio from the three nozzles. It is observed in the CFD simulations with varying the flowrate ratio of the three nozzles that the injection of a two times larger front nozzle flowrate than the side nozzle flowrate produces 8% higher $NO_x$ reduction efficiency than the injection of the equal ratio flowrate in each nozzle.

• Analytical Science and Technology
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• v.17 no.3
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• pp.251-262
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• 2004

It is for the purpose of investigating the tritium distribution in the leachates, the raw and treated leachates and the condensates of the methane gas, which have occurred from domestic solid waste landfills. Also it aims to measure the tritium distribution level on the colloid size of the leachates, the raw and treated leachates. It was found that the major inorganic contaminants of the leachates were Na, K, Ca, Mg, $NH{_4}^+$-N and $Cl^-$. The mean tritium level of the raw leachates of the investigated 13 landfill sites for 6 months was 17 ~ 1196 TU. It corresponded to a several scores or hundreds of magnitude higher value than that of the normal environmental sample level except for two landfill sites. Also such a high concentration of the tritium was found in the treated leachates and methane gas condensates as well. Nevertheless it is important to emphasize that the tritium level which was found in this research is about 100 times lower than the tritium limit for the drinking water quality. And most of the tritium existed in the dissolved colloid of the leachate of which the colloid size is below $0.45{\mu}m$. Also, according to the tritium analysis results of the leachates after filtration with $0.45{\mu}m$ membrane filter for some landfills, it is likely that some tritium of the leachate would be distributed in a colloid size over $0.45{\mu}m$. In general the relationship between the tritium and other contaminants in the raw leachate was low, but it was relatively high between the tritium and TOC. However, the tritium content in the leachate had no meaningful relationship with the scale, hydrological characteristics and age of the landfill.

• Journal of the Korean Recycled Construction Resources Institute
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• v.8 no.3
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• pp.317-324
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• 2020

Plastic wastes generated from domestic waste are separated by mixed discharge with foreign substances, and the cost of the separation and screening process increases, so recycling is relatively low. In this study, as a fundamental study for recycling mixed plastic wastes generated from domestic waste into concrete aggregates, changes in concrete properties according to the plastic waste types and the substitution rate were evaluated experimentally. The mixed plastic waste aggregate(MPWA) was found to have a lower density and a higher absorption rate compared to the coarse aggregate with good particle size distribution. On the other hand, the single plastic waste aggregate(SPWA) was composed of particles of uniform size, and both the density and the absorption rate were lower than that of the fin e aggregate. It was found that the MPWA substitution concrete did not cause a material separation phenomenon due to a relatively good particle size distribution even with the largest amount of plastic waste substitution, and the amount of air flow increased little. The compressive strength and flexural strength of the PWA substitution concrete decreased as the amount of substitution of the PWA increased due to the low strength of the PWA, the suppression of the cement hydration reaction due to hydrophobicity, and the low adhesion between the PWA and the cement paste. It was found that the degree of deterioration in compressive strength and flexural strength of concrete substituted with MPWA having good particle size distribution was relatively small.

• Journal of the Mineralogical Society of Korea
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• v.20 no.4
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• pp.267-275
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• 2007

Melting slag generated from municipal-incinerator ash contains lots of impurities which have adverse effects on zeolite synthesis. These impurities are detrimental to zeolite synthesis, and the yield and purity of zeolite was decreased. And thus its performance is lowered. In melting slag, there are lots of components such as $Fe_2O_3$, FeO and CaO. To remove these impurities, we treated the melting slag with hydrochloric acid at initial pH 1, 3, 5, and 7. After the treatment, the $SiO_2,\;Fe_2O_3,\;and\;TiO_2$ ratios increased, but the $Al_2O_3,\;FeO,\;CaO,\;Na_2O$ and MgO ratios decreased. We reacted these treated slag in a NaOH solution under hydrothermal conditions at $80^{\circ}C$. The hydrothermal products from the slag and the slag treated at pH 7 and pH 5 were determined to be tobermorite, whereas those at pH 3 and pH 1, Na-P1 and Na-X zoelite respectively. CaO was found to inhibit the synthesis of zeolite.

• Analytical Science and Technology
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• v.19 no.1
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• pp.86-95
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• 2006

This study was carried out to estimate leaching characteristics of incineration residues from municipal solid waste incinerators, and determine organic compounds in raw ash, leaching water and leaching residue. A total of 44 organic compounds, which were analyzed by GC/MSD and identified by wiley library search, were contained in bottom ashes. A total of 17 organic compounds were contained in fly ashes. Bottom ash and fly ash were found to contain a wide range of organic compounds such as aliphatic compounds and aromatic compounds. Organic compounds such as Ethenylbenzene, Benzaldehyde, 1-Phenyl-Ethanone and 1,4-Benzenedicarboxylic acid dimethyl ester were detected in raw ash, leaching water and residues (from bottom ash). Organic compounds such as Naphthalene, Dodecane, 1,2,3,5-Tetrachlorobenzene, Tetradecane, Hexadecane and Pentachlorobenzene were detected in raw ash, leaching water and residues (from fly ash). Through the leaching characteristics of incineration residue, it was represented that the open dumping of incineration residue can contaminate the soil and undergroundwater. In order to prevent environmental contamination that derived from extremely toxic substances in the incineration residues, it is particularly important that the incineration residues should be treated before disposal the incineration residues. Further study and proper management about leaching characteristics of organic compounds might be required.

• Journal of the Korean Society of Groundwater Environment
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• v.4 no.4
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• pp.175-184
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• 1997

The Seokdae Waste Landfill is a middle-sized site used from June, 1987 to May, 1993. Many joints and faults are developed in andesitic rocks and rhyolitic rocks distributed at the landfill. The chemical analyses of leachates, streams and groundwaters sampled in July, 1996 and June, 1997 show that the concentrations of leachates and streams were decreased, and that the groundwater qualities became worse. The groundwater contamination is deeply extended to not only shallow groundwater but also bedrock-groundwater around the Seokdae Waste Landfill Area. The range of groundwater contamination by the leachates is about 500 m to the west and about 1 km to the south from the boundaries of the waste landfill. The development of monitoring wells and pumping wells, the construction of a leachate-treatment facilities, and the adjustment of the existing grout curtains are necessary for the control of water pollution at the Seokdae Waste Landfill Area.

• Journal of Advanced Marine Engineering and Technology
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• v.34 no.6
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• pp.816-824
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• 2010

The forces applying to an object in the transferring pipe of waste are analyzed and the equation of motion is established in this paper. It is shown that the equation of motion becomes the 1st order non-linear differential equation. Using its general solution, the velocity of the object in the transferring pipe of waste can be expressed in the explicit form. Noting that the velocity of object is impact velocity to the elbow or curved part of the transferring pipe of waste, the kinetic energy of the object can be calculated and the necessary impact strength of inner wall is obtained. The velocity of object is also calculated and presented in the graphic forms with the condition of air velocity 30m/sec. The impact test of cast basalt tube is carried out by the free fall of a weight and the test results show that the impact strength of the cast basalt tube is sufficient to apply to protecting inner wall of the transferring pipe of waste.

• Journal of Korean Society of Water and Wastewater
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• v.11 no.4
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• pp.110-117
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• 1997

Performances of combined adsorption and coagulation were evaluated as one of the options for pre-treatment or post-treatment of MSW landfills leachate and industrial landfill leachate. The COD and color removals of leachate from an old MSW landfill were 35% and 33% at an alum dose of 300mg/L with preceding PAC(powdered activated carbon) dose of 200mg/L, respectively. The COD and color removals of leachate from an young MSW landfill were 58% and 25% at an alum dose of 700mg/L and PAC dose of 500mg/L, respectively. The COD and color of biologically treated leachate from an industrial waste landfill were removed up to 32% and 68%, respectively, with pH control at addition of 500mgAlum/L and 1,000mgPAC/L. Adsorption and coagulation process with pH control showed better COD and color removals than the process without pH control for biologically treated leachate from an industrial waste landfill. The color removal was influenced greatly by pH control, while COD removal was not significant. No difference in removal efficiency was observed between adsorption-coagulation and coagulation-adsorption process. The COD removal was accomplished mainly by adsorption, while coagulation was a key mechanism of color removal. However, the mechanism of COD removal was obscure, when BOD/COD ratio was high. Maximum net increases in COD and color removals by the adsorption-coagulation process were respectively 45% and 46% compared with the unit process of adsorption or coagulation, although those removals depended on leachate characteristics. Thus, adsorption-coagulation process was considered to be effective for pre- and post-treatment of landfill leachate, and has distinct features of simple, flexible, stable and reliable operation against fluctuation leachate quality and flowrate.

• Journal of the Korean Society for Marine Environment & Energy
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• v.15 no.1
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• pp.54-65
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• 2012

While fishery has been continuously suffering from deteriorating economic feasibility, the amount of the deposited marine litter has been increasing due to an increased number of marine leisure tourists which are caused by an improved quality of life and five-day work week. In addition, the fishery area has been reduced by the reclamation projects and it is being destroyed by marine pollution with a variety of contaminants coming from land and sea. To protect and improve fisheries in these poor conditions, Korean governments have implemented the submerged marine litter collection projects. However, previous research results on the marine environment and resources indicate that it requires a lot of time investment to achieve tangible results of such improvement. The 300 billion won marine environment and resource investigation project has been executed since July 2004 by Korean governments, which demands strategic approaches to obtain more effective and satisfactory results before the project expires in 2013. Ocean environment research institutes and governments need to cooperate each other to gain efficient and reasonable achievement by identifying and linking related projects. This study suggests that the marine environment and resources investigation projects should run parallel with the submerged marine litter collection projects on mutually agreed research items in the identical area of the ocean to obtain cost-effective improvement of marine environment and fishery conditions.