• Journal of Environmental Science International
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• v.16 no.1
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• pp.9-19
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• 2007

Comparing predicted PCDF isomer patterns with those obtained from a municipal waste incinerator assessed the role of two-phenol condensation pathways in the formation of PCDFs. Complete PCDF homologue and isomer distributions were obtained from a Fluidized Bed Incinerator (FBI). Two-phenol condensation model, dependent only on the distributions of phenols, was developed to predict the PCDF congeners produced from phenol precursors. R-squared values from linear correlations are presented for the dichlorinated through hexa-chlorinated isomer distributions between measured and predicted. They range from 0.00: to 0.1 far the di-chlorinated through hexa-chlorinated isomer sets. Agreement between predicted and measured PCDF isomer distributions was very poor for all homologues. Two-phenol condensation pathways are not likely to be the pre-dominant pathways in the formation of PCDF in a FBI. However, dibenzofuran (DF) is likely to be produced from a condensation of two phenols. This work demonstrates the use of PCDF homologue and isomer patterns for testing PCDF formation mechanism from two-phenol condensation pathways in municipal waste incinerators.

• 보일러설비
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• s.67
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• pp.114-115
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• 1999

• Polymer Science and Technology
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• v.9 no.6
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• pp.473-478
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• 1998

• Journal of the Korea Organic Resources Recycling Association
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• v.15 no.3
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• pp.97-105
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• 2007

This study was conducted to compare the performances of acidogenic fermentation and hydrogen fermentation using bench-scale leaching-bed reactors for organic solid waste. Acidogenic fermenters were operated with dilution rates (D) of 2.0, 3.0 and $4.0d^{-1}$ after employing anaerobic sludge and hydrogen fermenters were operated with D of 2.0, 4.0 and $6.0d^{-1}$ after employing heat-treated anaerobic sludge. The highest chemical oxygen demand (COD) conversion efficiency (56.2%) was obtained in acidogenic fermentation with D of $3.0d^{-1}$. Only volatile fatty acid (VFA) was produced as a metabolite. On the other hand, hydrogen fermentation did not show higher COD conversion efficiency (49.3%) than acidogenic fermentation, but it produced hydrogen gas (5.1% of total COD) which was a clean and environmentally friendly fuel with a high energy yield. Therefore, either acidogenic fermentation or hydrogen fermentation could be applied to organic solid waste depending on the purpose of treatment, which could maximize the economics of anaerobic treatment.

• Journal of Environmental Science International
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• v.11 no.10
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• pp.1089-1096
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• 2002

The objectives of this study were to investigate the desulfurization kinetics of paper sludge and limestone in a fluidized bed reactor according to bed temperature and air velocity. The experimental results were presented as follows ; First, the bed temperature had a great influence on the desulfurization efficiency of limestone and paper sludge. In paper sludge, the optimum condition in desulfurization temperature was at 80$0^{\circ}C$ and in limestone, that was at 850 $^{\circ}C$ or 900 $^{\circ}C$ Second, as air velocity increased, the desulfurization efficiency(or the absorbed amount of sulfur dioxide) by limestone and paper sludge decreased. And the absorbed amount of sulfur dioxide by paper sludge was larger than that of by limestone. Third, as the velocity increased and the optimum desulfurization temperature became, ks and the removal efficiency increased. So, ks, kd highly depended on the air velocity and bed temperature.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.15 no.8
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• pp.690-696
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• 2003

This paper presents the heat recovery performance of water fluidized-bed heat exchanger. Temperature and humidity ratio of waste gas are considered as important parameters in this study. Therefore, the heat recovery rate through water fluidized-bed heat exchanger for exhaust gases with various temperatures and humidity ratios can be estimated from the results of this study. Mass flow ratio (the ratio of mass flow rate of water to that of gas) and temperature of inlet water are also considered as important operating variables. Increase of heat recovery rate can be obtained through either high mass flow ratio or low temperature of inlet water with resultant low recovered temperature. The heat recovery performance with the mass flow ratio of about up to 10 has been investigated. The effect of number of stages of water fluidized-bed on the heat recovery performance has been also examined in this study.

• Journal of the Korean Solar Energy Society
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• v.22 no.1
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• pp.9-21
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• 2002

To develope chemical heat pump using available energy sources, solar heat and other kinds of waste thermal energy, we have studied the heat transfer rate in cylindrical bed reactor packed with calcined Dolomite. Two dimensional (radial and circumferential) Partial differential equations, concerning heat and mass transfer in packed bed of calcined Dolomite, are solved numerically to describe the characteristics of the reaction of calcined Dolomite and heat transfer. The results obtained by numerical analysis about two dimensional profiles of temperature and conversion of reactant in the packed bed reactor and the amount of exothermic heat released from the reactor are follows. It was found that all of calcined Dolomite packed bed kept the reaction temperature of about 750K throughout the entire part of the bed, immediately after the steam was introduced exothermic reaction of hydration was proceeded from the packed bed inpu to output and from wall side to center. The rate of thermochemical reaction depends on the temperature and concentration and it is also governed by the boundary conditions and heat transfer rate in the particle packed bed.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 1996.06c
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• pp.957-966
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• 1996

An attempt was made to measure the availability of waste heat, released from the cooling system of a small engine, which can be utilized for grain drying. An engine powered flat-bed rough rice dryer was constructed and the performance of the dryer with available engine-waste heat was analyzed for 10 , 20, 30 and 40 cm rough rice bulk depths with a constant dryer base area of 0.81$m^2$/min. The waste heat was sufficient to increase the drying air temperature 7 to 12$^{\circ}C$ at an air flow rate of 8.8 to 5.7㎥/min, while the average ambient temperature and relative humidity were 24$^{\circ}C$ and 70%. The minimum energy requirement was 3.26 MJ/kg of water removed in drying a 40 cm deep grain bed in 14h. A forty to fifty centimeter deep grained seems to be optimum in order to avoid over-drying in the top layers. On the basis of minimum energy requirement (3.26 MJ/kg ) , an estimation was made that the waste heat harvest from an engine of a power range of 1 to 10.5PS can dry about 0.1 to 1 metric on of rough rice from 23% to 15% m.c. (w.b) in 12 h at an average ambient temperature and relative humidity of $25^{\circ}C$ and 80%, respectively. The engine-waste heated grain dryer can be used in the rural areas of non industrialized countries where electricity is not available.

• Ocean Science Journal
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• v.40 no.2
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• pp.91-100
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• 2005

Bioassay using the marine bacteria, Vibrio fischeri and rotifer, Brachionus plicatilis, and chemical analyses were conducted to assess the toxicity of the various sewage sludges, one of the major ocean dumped materials in the Yellow Sea of Korea. Sludge elutriates extracted by filtered seawater were used to estimate the ecotoxicity of the sludge. Chemical characterization included the analyses of organic contents, heavy metals, and persistent organic pollutants in sludge. Bacterial bioluminescent inhibition (15 min), rotifer mortality (24 hr) and rotifer population growth inhibition (48 hr) assay were conducted to estimate the sludge toxicity. EC50 15 min (inhibition concentration of bioluminescence after 15 minutes exposed) values by Microtox(R) bioassay clearly revealed different toxicity levels depending on the sludge sources. Highest toxicity for the bacteria was found with the sludge extract from dyeing waste and followed by industrial waste, livestock waste, and leather processing waste. Clear toxic effects on the bacteria were not found in the sludge extract from filtration bed sludge and rural sewage sludge. Consistent with Microtox(R) results, rotifer neonate mortality and population growth inhibition test also showed highest toxicity in dyeing waste and low in filtration bed and rural sewage sludge. High concentrations of persistent organic pollutants (POPs) and heavy metals were measured in the samples from the industrial wastes, leather processing plant waste sludge, and urban sewage sludge. However, there was no significant correlation between pollutant concentration levels and the toxicity values of the sludge. This suggests that the ecotoxicity in addition to the chemical analyses of various sludge samples must be estimated before release of potential harmful waste in the natural environment as part of an ecological risk assessment.

• Journal of the Korea Organic Resources Recycling Association
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• v.8 no.3
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• pp.112-117
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• 2000

Food waste is the main source of decay, odors and leachate in collection, transportation and landfill due to the high volatile solids (VS) and moisture content. Acidogenic fermentation of food waste is affected by the fermentation constraints including the biodegradability of substrate and the degrading capability of microorganisms. The biodegradability of food waste is mainly related to cellulosic materials, which are hardly degraded and comprise about 50% of food waste. The efficient and economical method of improving hydrolysis is, therefore, to apply microorganisms with increased cellulose-degrading capability. In this experiment, rumen microorganisms were inoculated to improve the low efficiency of acidogenic fermentation, and then compared with that of mesophilic acidogens. The fermentation of food waste in a leaching bed reactor employing rumen microorganisms resulted in the enhanced acidification (71.2% at $3.0d^{-1}$), which was higher than that (59.8% at $4.5d^{-1}$) employing mesophilic acidogens. This indicated that Rumen microorganisms had an enhanced waste-degrading capability.