• Journal of the Korea Organic Resources Recycling Association
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• v.24 no.1
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• pp.31-40
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• 2016

In this study, mesophilic anaerobic digestion of source separated food waste was carried out by leachate recirculation system and methane gas was produced. Two systems - system A and B were fabricated and placed within water bath to maintain $36^{\circ}C$. Each system was comprised of an anaerobic bioreactor and a leachate tank. Leachate in bioreactor was separated through the screen located at 30 mm above the bottom and a pump was installed to transfer collected leachate to the leachate tank. Everyday, 2.5 L of the leachate was pumped from the bioreactor to the leachate tank for 30 min and transferred leachate was pumped back to the top of the bioreactor for 30min, sequentially. Source separated food waste used for this experiment was washed by water before transferring to the laboratory. Transferred food waste was warmed to $36^{\circ}C$ before being fed to bioreactors. System A was fed to 49.1 g VS (Volatile Solids) and System B was fed to 54.0 g VS at every two weeks, respectively. $NH_4{^+}-N$ and salinity were monitored to see the inhibition toward anaerobic bioreaction and it was found that concentrations of these materials were not high enough to affect the bioreaction. Although the food waste was fed biweekly for 112 days and 140 days at system A and B, respectively, there was no sludge withdrawal from each system. Average methane productions rates were 0.439 L $CH_4/g$ VS and 0.368 L $CH_4/g$ VS for system A and B, respectively.

• Korean Journal of Environmental Agriculture
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• v.26 no.1
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• pp.1-6
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• 2007

In view of energy supply, biogas can be seen as alternative fuel by substituting considerable amount of fossil fuel and may be utilized for heat and power production or for transport fuel production ($CH_4-enriched$ biogas). The aim of this research is to analyse the emission of $NO_x$ and CO from biogas fired combustion engine for electric power production. The result indicate a significant effect of biogas composition ($CH_4-CO_2$ ratio) and biogas flow rate on the air pollutants emission. The emission factors from this study were compared with those of U.S. EPA. Low $CH_4-CO_2$ ratio condition typically shows the lower $NO_x$ and CO emission than higher $CH_4-CO_2$ ratio condition. At normal $CH_4-CO_2$ ratio (7:3) emission factors of $NO_x$ and CO were 1.29 and 30.43 g/MMBtu, respectively. At low $CH_4-CO_2$, ratio (6:4) emission factors of $NO_x$ and CO were 0.646 and 60.86 g/MMBtu, respectively, It should be emphasized that the actual emission may vary considerably from these results due to operating conditions including torque load and engine speed.

• 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.

• Applied Chemistry for Engineering
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• v.10 no.5
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• pp.754-760
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• 1999

The properties of the catalyst for a direct internal reforming type molten carbonate fuel cell were examined by ICP, BET, CHN, EDS, and $H_2$ chemisorption. Potassium and lithium, the components of carbonate electrolyte, were transported to the catalyst during the operation of fuel cell, and the amounts of the deposited alkali elements were reduced in the order of inlet, outlet, and the middle. From the direct correlation between the amount of alkali and the physical properties such as BET surface area and Ni dispersion, and from the observation of the lump of the alkali species on the poisoned catalyst, it was confirmed that the physical blocking of the catalyst by alkali deposition was the main reason for the deactivation. Although the amount of alkali species was greater at the inlet than at the oulet, the catalyst sampled from the outlet had lower activity. This was caused by the chemical interaction between the alkali species and the catalyst at the outlet where temperature was highest in the cell body, which was detected by FT-IR analyses.

• Polymer(Korea)
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• v.29 no.2
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• pp.177-182
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• 2005

Montmorillonite (MMT) modified with siloxane diamine was reacted with a reactant obtained from 4,4'-diphenyl methane diisocyanate (MDI) and polyester type polyol, $Nippollan4010(\bar{M}_n2000)$. Finally, polyurethane (PU)/MMT composites were prepared by using 1,4-butane diol as a chain extender in $25\;wt\%$ solution of N,N-dimethyl acetamide (DMAc). It was expected that these nanocomposites had superior exfoliation property to that of MMT dispersed polyurethanes produced by simple mixing due to insertion of siloxane main chain to the silicate interlayer of MMT. Extent of reaction and formation of final products were analysed by using FT-IR spectroscopy. Dispersion into the PU and intercalation of MMT were identified by applying X-ray diffraction (XRD) and transmission electron microscopy (TEM). Tensile data were acquired by universal test machine (UTM). Thermal stability and variation of surface energy were characterized by thermal gravimetric analysis (TGA) method and measurement of contact angle on the synthesized composites, respectively. As the results the organo-MMT modified with siloxane diamine in the PU composites has an intercalated structure relatively well-expanded rather than a completely exfoliated structure. The tensile strengths and the moduli for the PU/organo-MMT composites were drastically enhanced in comparison to those of $PU/Na^+-MMT$ composites.

• Journal of the Korea Organic Resources Recycling Association
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• v.15 no.2
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• pp.118-127
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• 2007

This study investigated the effect of varying TS concentration levels using supernatant of food waste. The experiment was performed at varying TS concentration levels ranging from 5% to 10% by a $35^{\circ}C$-mesophilic digestion reactor, dual digestion system with acid and methane fermenters combined. As a result, removal efficiency and stabilization were observed at TS concentration of 7~8%, But the removal efficiency notably decreased at 8% or higher TS level. At a stabilized phase of the reactor, more than $0.3m^3/kg{\cdot}vs$ gas was produced, with phenomena such as salt accumulation and increase of pH level being unnoticed. These results indicate that the increase of anaerobic digestion of food waste supernatant TS content has an effect on reaction and that it is necessary to control and operate concentration within 8%, given that the effect is stronger at 8% or higher.

• Applied Biological Chemistry
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• v.41 no.1
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• pp.104-109
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• 1998

Methanol extracts from 84 Indian plant samples (50 species in 31 families) and 27 African plant samples (20 species in 12 families) in vitro were tested for their growth-inhibitory activities against Bifidobacterium bifidum, Bifidobacterium longum, Lactobacillus acidophilus, Clostridium perfringens, and Escherichia coli, using a paper disc agar diffusion method under $O_2-free$ conditions. The responses varied with bacterial strain, plant species and plant part. Extracts from Cymbopogon citratus whole plants, Ocimum basilicum whole plant, Madhuca indica flowers, and Aegle marmelos leaves among Indian plant samples moderately or strongly inhibited the growth of Cl, perfringens whereas moderate growth-inhibitory activity against E. coli was obtained from extract of Indian O. basilicum whole plants. These plant extracts did not affect the growth of the lactic acid forming bacteria tested. These results may be an indication of at least one of the pharmacological actions of these tropical plants.

• Fire Science and Engineering
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• v.24 no.5
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• pp.128-135
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• 2010

In this study, a mixture fraction analysis was performed to investigate the characteristics of chemical species production in compartment fires burning hydrocarbon fuels such as methane, heptane, and toluene. A series of fire experiments was conducted in the ISO 9705 standard room, and gas species concentration and soot fraction were measured at two locations in the upper layer of the compartment. The mass fractions of measured chemical species, such as unburned hydrocarbons (UHC), carbon monoxide (CO), carbon dioxide ($CO_2$), oxygen ($O_2$), and soot were presented as a function of mixture fraction and compared with state relationships based on the idealized reaction of hydrocarbon fuels. The mixture fraction analysis made it possible to rearrange hundreds of species measurements, which were done under various fire conditions and at two locations of the upper layer, in term of the unified parameter, i.e. the mixture fraction. The results also showed that inclusion of soot in the mixture fraction calculation could improve the performance of analysis, especially for the sooty fuels such as heptane and toluene.

• Land and Housing Review
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• v.2 no.1
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• pp.87-92
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• 2011

The anaerobic digestion of food waste effluent through single- and two-phase process was estimated and compared in this study. The treatment efficiencies for total solid(TS), volatile solid(VS), tCOD(total COD) and sCOD(soluble COD) were invariably higher in the single-phase process, which was accounted for by the fact that the treatment efficiency of organic wastes usually showed an inverse relationship with organic loading rate in the anaerobic digestion. In fact, the organic loading rate was lower for single-phase process. The concentration of tCOD were significantly lower in two-phase process but much more biogas was produced, compared to single-phase anaerobic digestion process, which might be explained partly by the relatively higher stability of two-phase process resulting from the separation of acid phase from methane phase.

• Applied Chemistry for Engineering
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• v.22 no.2
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• pp.203-208
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• 2011

Dumping of wastes at sea will be strongly prohibited from 2012 by London Dumping Convention. So, finding the method for treatment of food waste at ground is needed urgently. The solution for above mentioned problem is the resource development from food waste leachate by using Upflow Anaerobic Sludge Blanket (UASB) process. In this research, we try to find out the effect of effluent recirculation and internal return influence on organic removal efficiency and biogas production. Laboratory investigation was conducted for 25 days with only internal recycling, and then, effluent recirculation was performed. As the result of experiments, the organic removal efficiency was above 90%, and the content of methane was 78~80% during operating time. Also, when UASB reactor was operated to over the 3 Q effluent recirculation, there was not 1 N-NaOH consumption any more, therethrough the experiment was economically and stably carried out.