• Journal of environmental and Sanitary engineering
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• v.23 no.3
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• pp.1-8
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• 2008

Currently, medical waste stoker incinerator is widely used in the emission control technology of health-care risk waste and miscellaneous contaminated waste. In the past, wet type control technology was used to remove the major harmful gaseous contaminants of medical waste such as HCl, $NO_x,\;SO_2$, CO, DUST, Dioxin. However, the treatment cost for wastewater was high and it has a disadvantage for frozen system during winter season. Therefore, in order to obtain effective treatment, the dry type control technology was developed and widely used to remove the gaseous contaminants. In this study, pre-coated bag filter using hydrated lime, ($Ca(OH)_2$), was applied to the dry type control system and the optimum dose of hydrated lime was investigated. The treatment results showed that the dust collection rate was approximately 26.7%. Moreover, the HCl removal rate using pre-coated bag filter ($50mg/sm^3\;Ca(OH)_2$) was 13.52%, which was significantly higher than 3.26% obtained from conventional bag filter.

• Clean Technology
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• v.15 no.1
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• pp.60-66
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• 2009

Adsorptive removal of tetrahydrothiophene (THT) and tert-butylmercaptan (TBM) that were widely used sulfur odorants in pipeline natural gas was studied using various ion-exchanged NaY zeolites at ambient temperature and atmospheric pressure. In order to improve the adsorption ability, ion exchange was performed on NaY zeolites with alkali metal cations of $Li^+,\;Na^+,\;K^+$ and transition metal cations of $Cu^{2+},\;Ni^{2+},\;Co^{2+},\;Ag^+$. Among the adsorbents tested, Cu-NaY and Ag-NaY showed good adsorption capacities for THT and TBM. These good behaviors of removal of sulfur compound for Cu-NaY and Ag-NaY zeolites probably was influenced by their acidity. The adsorption capacity for THT and TBM on the best adsorbent Cu-NaY-0.5, which was ion exchanged with 0.5 M copper nitrate solution, was 1.85 and 0.78 mmol-S/g at breakthrough, respectively. It was the best sulfur capacity so far in removing organic sulfur compounds from fuel gas by adsorption on zeolites. While the desorption activation energy of TBM on the Cu-NaY-0.5 was higher than NaY zeolite, the difference of THT desorption activation energy between two zeolites was comparatively small.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.11
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• pp.3246-3252
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• 2009

The interest on the recovery of thermal energy using the waste has been rising to solve the problems of continuous increase of waste generation and the depletion of the fossil fuel recently. The incineration has been used most popularly as a treatment process of the waste for the energy recovery. However, it is expected that incineration and design cost will increase in the treatment of air contaminant emitted from incinerator. This research has simulated the actual incinerator and the flue gas treatment system using the Aspen plus which is the software to simulate the chemical process. The incineration process is composed of the 1st and 2nd combustor to burn the waste, SNCR process to reduce the $NO_x$ using the urea, and the steam generation process to save the energy during incineration. The $Ca(OH)_2$ slurry was used as an acid gas (HCl, $SO_2$) treatment materials and the removal efficiency for the products from the neutralization of acid gas in SDA and combustion ash was simulated at the bag filter. The simulation result has been corresponded with the treatment efficiency of emitted gas from the actual industrial waste incinerator and it is presumed to be used to forecast the efficiencies of flue gas treatment system in the future.

• Plant Journal
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• v.12 no.1
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• pp.24-28
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• 2016

In desulfurization facilities of oil-fired power plant, gypsum scale is attached in the absorber inner surface as the operating time increases. For this reason, the maximum possible load of the power generation is set down, resulting in further generation stop. Cleaning of absorber for scale removal can be determined at the time of setting down of the maximum possible load. In this study, 6 weeks before the maximum possible load of the power generation was down set, at the same time and desulfurization facilities outlet $SO_2$ concentration value was more than 130ppm, absorber differential pressure exceeded $380mmH_2O$, it was confirmed to be the time that has elapsed 44 weeks after the previous absorber cleaning. Cleaning time of the absorber was predicted to be a time which has elapsed 50 weeks from the previous cleaning time.

• Korean Journal of Soil Science and Fertilizer
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• v.45 no.5
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• pp.853-860
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• 2012

To estimate potential use of fly ash in reducing $CH_4$ and $CO_2$ emission from soil, $CH_4$ and $CO_2$ fluxes from a paddy soil mixed with fly ash at different rate (w/w; 0, 5, and 10%) in the presence and absence of fertilizer N ($(NH_4)_2SO_4$) addition were investigated in a laboratory incubation for 60 days under changing water regime from wetting to drying via transition. The mean $CH_4$ flux during the entire incubation period ranged from 0.59 to $1.68mg\;CH_4\;m^{-2}day^{-1}$ with a lower rate in the soil treated with N fertilizer due to suppression of $CH_4$ production by $SO_4^{2-}$ that acts as an electron acceptor, leading to decreases in electron availability for methanogen. Fly ash application reduced $CH_4$ flux by 37.5 and 33.0% in soils without and with N addition, respectively, probably due to retardation of $CH_4$ diffusion through soil pores by addition of fine-textured fly ash. In addition, as fly ash has a potential for $CO_2$ removal via carbonation (formation of carbonate precipitates) that decreases $CO_2$ availability that is a substrate for $CO_2$ reduction reaction (one of $CH_4$ generation pathways) is likely to be another mechanisms of $CH_4$ flux reduction by fly ash. Meanwhile, the mean $CO_2$ flux during the entire incubation period was between 0.64 and $0.90g\;CO_2\;m^{-2}day^{-1}$, and that of N treated soil was lower than that without N addition. Because N addition is likely to increase soil respiration, it is not straightforward to explain the results. However, it may be possible that our experiment did not account for the substantial amount of $CO_2$ produced by heterotrophs that were activated by N addition in earlier period than the measurement was initiated. Fly ash application also lowered $CO_2$ flux by up to 20% in the soil mixed with fly ash at 10% through $CO_2$ removal by the carbonation. At the whole picture, fly ash application at 10% decreased global warming potential of emitted $CH_4$ and $CO_2$ by about 20%. Therefore, our results suggest that fly ash application can be a soil management practice to reduce green house gas emission from paddy soils. Further studies under field conditions with rice cultivation are necessary to verify our findings.

• Transactions of the Korean hydrogen and new energy society
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• v.21 no.6
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• pp.519-525
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• 2010

Ethanol was used as reductant to remove $NO_x$ over Ag/$Al_2O_3$ catalyst via SCR from stationary emission source. Among the tested hydrocarbon reductants, ethanol showed highest de-$NO_x$ performance over the Ag/$Al_2O_3$ catalyst. De-$NO_x$ efficiency of about 83% was obtained in the condition of GHSV 20,000 $hr^{-1}$, $NO_x$ 200 ppm, CO 200 ppm, $O_2$ 13%, $H_2O$ 5% and mole ratio of ethanol/$NO_x$ = 2 between temperature of $300^{\circ}C$ and $400^{\circ}C$. While $SO_2$ presence in the $NO_x$ exhaust suppressed the catalytic activity, catalyst with acid (0.7% $H_2SO_4$) treatment of catalyst showed higher catalytic activity, where In-Situ DRIFT showed S presence over catalyst surface was increased after acid treatment of catalyst. From in-situ DRIFT and SCR results, it was concluded that sulfur presence over the surface of Ag/$Al_2O_3$ catalyst was the dominant factor to control the de-$NO_x$ reaction yield via HC-SCR from the exhausted gas including $SO_2$.

• Journal of the Korea Organic Resources Recycling Association
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• v.8 no.3
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• pp.89-96
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• 2000

Waste oyster shell was used to study the applicability on anaerobic composting of garbage. Experiment was conducted with five anaerobic reactors. After garbage and compost for inoculation were mixed, waste oyster shell was added into mixed waste in mesophillic temperature for 60 days with 30%, 60% respectively. The amount of produced methane gas, gas composition, organic removal efficiency and pH were measured. Result showed that the amounts of produced gas were 0.62 l /g-VS in R-1, 0.63 l /g-VS in R-2, 0.16 l /g-VS in R-3, 0.75 l /g-VS in R-4, 0.21 l /g-VS in R-5 and the amounts of produced methane gas were 0.32 l /g-VS in R-1, 0.37 l /g-VS in R-2, 0.04 l /g-VS in R-3, 0.42 l /g-VS in R-4, 0.05 l /g-VS in R-5. Proportion of mathane gas which determines the efficiency of anaerobic composting was over 55%. pH were 6.0~8.0 in R-2 and R-4 which contained 30% of waste oyster shell and pH were increased over 8.5 in R-3 and R-5 which contained 60% of waste oyster shell. Since pH were so high and it had a negative effect on microbial growth, anaerobic reaction were not well operated in R-3 and R-5.

• Journal of The Korean Society of Grassland and Forage Science
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• v.34 no.3
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• pp.193-201
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• 2014

This study was conducted to examine the effects of defaunation (removal of live protozoa) on fermentation characteristics, degradation of ryegrass hay and $CH_4$ (methane) production by rumen microbes when incubated with plant oils (SO, sunflower oil and LO, linseed oil) in vitro. Sodium lauryl sulfate (0.000375 g/ml) as a defaunation reagent was added into the culture solution and incubated anaerobically up to 24 h at $39^{\circ}C$. pH from defaunation was increased for all treatments from 6 h incubation times (p<0.01-0.001) compared with those from fauantion. Concentration of ammonia-N from defaunation is higher than that from faunation at 3 h (p<0.001), 12 h (p<0.05) and 24 h (p<0.001) incubation times. Defaunation decreased (p<0.01-0.001) total volatile fatty acid concentration at all incubation times. Molar proportions of $C_2$ (acetate, p<0.05-0.001) and butyrate (p<0.01-0.001) were also decreased by defaunation at all incubation times. Molar proportion of $C_3$ (propionate), however, was increased by defaunation at all incubation times (p<0.001). Thus the rate of $C_2$ to $C_3$ was decreased by defaunation at all incubation times (p<0.001). Defaunation decreased ED (effective degradability) of dry matter (p<0.001) and ED of neutral detergent fiber (p<0.001) of ryegrass hay. Defaunation decreased total gas, $CH_4$ production, $CH_4$ % in total gas and $CH_4/CO_2$ at all incubation times (p<0.001). Oil supplementation decreased total gas (p<0.05-0.001), $CH_4$ production (p<0.001) and $CH_4$ % in total gas (p<0.001) compared with control at all incubation times. The result of this study showed that defaunation combined with oil supplementation may cause an alteration of microbial communities and further medicate the fermentation pattern, resulting in both reduction of degradation of ryegrass hay and $CH_4$ production. No difference, however, was observed in all the examinations between SO and LO.

• Korean Chemical Engineering Research
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• v.56 no.3
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• pp.297-302
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• 2018

Bead type and hollow fiber type catalyst (HFC, Hollow Fiber type Catalyst) was prepared by $La_{0.1}Sr_{0.9}Co_{0.2}Fe_{0.8}O_{3-{\delta}}$ (LSCF1928) perovskite powder catalyst which showed excellent methane complete oxidation characteristics through previous studies. The HFC have a cylindrical shape with an empty interior, and pores can be formed through Phase inversion method so the specific surface area can be remarkably improved. In the case of the bead type catalyst prepared by adding Methyl Cellulose (MC), $SrCO_3$ was produced in addition to the original catalyst composition of LSCF1928 due to the reaction of $CO_2$ emitted from MC and Sr of the catalyst. In the case of the HFC, a single phase perovskite structure was obtained without impurities. The HFC calcined at $700{\sim}900^{\circ}C$ showed pore structure of finger-sponge-finger structure, and 99.9% oxygen conversion rate was achieved through complete oxidation of methane at $475^{\circ}C$. Air gap and spinning pressure condition were changed to control the HFC pore. 2 cm air gap and 7 bar spinning pressure showed the best catalytic performance and achieved oxygen conversion rates of more than 70.65%, 93.01%, and 99.99% at $425^{\circ}C$, $450^{\circ}C$ and $475^{\circ}C$, respectively.

• Journal of Appropriate Technology
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• v.7 no.1
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• pp.59-71
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• 2021

Hybrid hydrothermal carbonization (Hybrid HTC) technology is a proprietary thermochemical process for two or more organic wastes.The reaction time is less than two hours with temperature range 180~250℃ and pressure range 20~40bar. Thanks to accumulation of the carbon of the waste during Hybrid HTC process, the energy value of the solid fuel increases significantly with comparatively low energy consumption. It has also a great volume reduction with odor removal effect so that it is evaluated as the best solid fuel conversion technology for various organic wastes. In this study of the hybrid hydrothermal carbonization, the effect on the calorific value and yield of Cambodian mango waste were evaluated according to changes in temperature and reaction time. Through the study, parameter optimization has been sought with improving energy efficiency of the whole plant. It is decomposed in the Hydro-Carbonation Technology to Generate Gas. At this time, it is possible to develop manufacturing and production technologies such as hydrogen (H₂) and methane (CH₄). Based on the results of the study, a pilot plant (2t/day) has been proposed for future commercialization purpose along cost analysis, mass balance and energy balance calculations.