• Journal of Energy Engineering
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• v.25 no.1
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• pp.29-42
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• 2016

This study analyzes the economic efficiency of utilizing hot waste water at a thermoelectric power plant, which is part of recent projects supported by the Korean government to foster new energy industry. The author proposes an institution that provides economic incentives to promote the project. Based on a method of calculating Levelized cost of energy (LCOE), this study finds that the LCOE of using hot waste water at power plants is higher than that of oil boiler, biomass and a power plant's auxiliary steam but similar to that of the geothermal system. Also, according to sensitivity analysis on the LCOE of each element in the system of using hot waste water, a distance of heat supply is most sensitive. Therefore, this study shows that when the government devises an incentive-based institution to expand the project of utilizing hot waste water, it is necessary to establish Renewable Energy Certificate (REC) weights that are differentiated by a distance of heat supply.

• Korean Journal of Agricultural and Forest Meteorology
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• v.5 no.1
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• pp.36-42
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• 2003

To identify the rapacity of waste leachate absorption in Populus euramericana and Betula platyphylla var, japonica, four different treatments were applied to seedlings: leachate solution (100% leachate), 50% dilution (50% leachate: 50% water, v/v) and 25% dilution, (25% leachate: 75% water, v/v) were applied to these two species. After the experiment, concentrations of heavy metals in tree parts were analyzed by an Inductively Coupled Plasma emission spectrometer (ICP). treatment with waste leachate significantly stimulated both Populus euramericana and Betula platyphylla var. japonica biomass production relative to the water control. In addition, these species showed good absorption capacity of As, Co, Hg and Ni elements. The results of this study suggested that these two species can absorb the toxic materials through their roots and transport them to stems or leaves.

• Membrane Journal
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• v.31 no.5
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• pp.327-332
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• 2021

The use of membranes for MBRWG (Membrane Bioreactor for Waste Gas) treatment can provide highly selective separation of a waste gas stream followed by effective biological removal. MBRWG have several potential advantages, among which the most distinctive one is separation of gas and liquid phases at each side of membrane potentially allowing the optimal biomass control toward effective biodegradation of target gases as well as biofilm activation. This advantage becomes especially favorable for removal of hydrophobic toxic gases, such as xylene, by MBRWG systems, because the mass transfer, the toxicity, and thereby the biodegradation of hydrophobic gas treatment requires sensitive handling of liquid stream and water control near biofilm. Among various membranes for MBRWG treatment, PDMS-hollow fiber membranes provide the high gas mass transfer. Despite lower specific surface areas, capillary type membranes are also applied current MBRWG studies. In addition to the main application of membranes as biofilm supporter in MBRWG systems, there can be another application of membranes in a posterior process for removal of residual gases or dusts emitted from conventional biological waste gas treatment processes.

• Clean Technology
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• v.28 no.2
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• pp.97-102
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• 2022

Lithium sulfur (Li-S) batteries have attracted considerable attention as a promising candidate for next-generation power sources due to their high theoretical energy density, low cost, and eco-friendliness. However, the poor electrical conductivity of sulfur and its insoluble discharging products (Li₂S₂/Li₂S), large volume changes, severe self-discharge, and dissolution of lithium polysulfide intermediates result in rapid capacity fading, low Coulombic efficiency, and safety risks, hindering Li-S battery commercial development. In this study, a three-dimensionally (3D) connected hierarchical porous carbon framework (HPCF) derived from waste sunflower seed shells was synthesized as a sulfur host for Li-S batteries via a chemical activation method. The natural 3D connected structure of the HPCF, originating from the raw material, can effectively enhance the conductivity and accessibility of the electrolyte, accelerating the Li⁺/electron transfer. Additionally, the generated micropores of the HPCF, originated from the chemical activation process, can prevent polysulfide dissolution due to the limited space, thereby improving the electrochemical performance and cycling stability. The HPCF/S cell shows a superior capacity retention of 540 mA h g^-1 after 70 cycles at 0.1 C, and an excellent cycling stability at 2 C for 700 cycles. This study provides a potential biomass-derived material for low-cost long-life Li-S batteries.

• Textile Coloration and Finishing
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• v.30 no.4
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• pp.294-303
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• 2018

In this study, eco-friendly natural dyeing for pig leather was explored by using onion skin which is food waste. Sodium caseinate was used as a pre-treatment agent to improve dyeability of pig leather and its effect on dye uptake was investigated according to treatment concentration. Dye uptake of the pre-treated pig leather was increased by about two times compared to untreated one at 0.2% pre-treatment concentration. Onion skin colorant imparted YR color on pig leather. After mordanting, the color of pretreated/dyed pig leather was varied from brick-red to khaki shades. However, mordanting did not improved dye uptake of the pre-treated/dyed pig leather significantly. The color-fastnesses of un-mordanted samples to light, dry cleaning, rubbing were grades 3-4, 5, and 4, respectively, which is good enough to meet all Korean Standard for Fastness of leather products. After mordanting, the light fastness of pig leather was improved to 4, 4-5 grade. The efficacy of sodium caseinate as a pre-treatment agent for pig leather was verified by improved dye uptake and good colorfastness. And, the natural dyeing of pig leather using food waste would be a significant sustainable way in terms of eco-friendliness and reuse of biomass to reduce environmental pollution.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.6 no.2
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• pp.73-100
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• 2008

For the purpose of evaluating dose rate to individual due to long-term release of nuclides from the HLW repository, a biosphere assessment model and the implemented code, ACBIO, based on BIOMASS methodology have been developed by utilizing AMBER, a general compartment modeling tool. To show its practicability and usability as well as to see the sensitivity of compartment scheme or parametric variation to concentration and activity in compartments as well as annual flux between compartments at their peak values, some calculations are made and investigated: For each case when changing the structure of compartments and GBIs as well as varying selected input Kd values, all of which seem very important among others, dose rate per nuclide release rate is separately calculated and analyzed. From the maximum dose rates (Bq/y), flux-to-dose conversion factors (Sv/Bq) for each nuclide were derived, which are to be used for converting the nuclide release rate appearing from the geosphere through various GBIs to dose rate (Sv/y) for individual in critical group. It has been also observed that compartment scheme, identification of possible exposure group and GBIs could be all highly sensitive to the final consequences in biosphere modeling.

• Journal of the Korean Society for Marine Environment & Energy
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• v.10 no.2
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• pp.112-117
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• 2007

This study aims to develop an alternative energy like oil made from marine organic waste by marine products waste, spent fishing nets. There are already many commercial examples and case studies based on the petroleum industry-refuse plastic or refuse tire, however, it is rare that a research developing alternative energy from food waste and organic waste. Therefore, this study investigated the oil made from thermal decomposition under the high temperature and high pressure condition, and examined the possibility for commercial use by testing its own characteristics. A bio-oil from thermal decomposition at $250^{\circ}C$ and 40 atm was hard to remove impurities because of its high viscosity, showed lower caloric value than heavy oil, and generated various gases which were not appropriate for the use of fuel. It is noticeable that thermal decomposition was occurred at $250{\pm}5^{\circ}C$ using steam pressure, which much lower compared to the existing method of thermal decomposition, more than $500^{\circ}C$. Since the high viscosity of bio-oil, it is necessary a further study to use as liquid fuel.

• Applied Chemistry for Engineering
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• v.23 no.2
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• pp.125-130
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• 2012

In these days, there has been increased focus on global warming and the exhaustion of resources recently caused by the heavy consumption of fossil resources. In order to resolve these problems, biomass is increasingly gaining international attention as a renewable energy source. Biogas derived from various biomass is environmental friendly alternative fuel for power generation, heating and vehicle fuel. Large amounts of sewage sludge, food waste and manure are generated from human activity, but these organic wastes contain high levels of organic matter and thus they are potential substrates for producing methane of biogas. The biogas contains 60% of highly concentrated methane, which is expected to be used effectively as energy. In this paper, we investigate the status of biogas in Korea as an alternative energy.

• Journal of Soil and Groundwater Environment
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• v.19 no.1
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• pp.1-7
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• 2014

When processing the biomass by Hydrothermal carbonization (HTC), a slow pyrolysis process, it produces bio-gas, biooil, and biochar. Among these end products, biochar is known for isolating or storing carbon and being used as a soil amendment. In this study, the characteristics of biochar generated by HTC at $250^{\circ}C$ for 1 hour, 2 hours, 3 hours, and 20 hours with synthetic food wastes and wood wastes were analyzed for potential uses in soil contaminated with heavy metals. The yield of biochar (weight %) increased when the ratio of wood wastes increased and showed a decreasing tendency as reaction time increased. Elemental analysis of biochar based on various conditions showed a maximum of 70% carbon (C) content. The carbon content showed an increasing tendency with the increase of wood wastes. Iodine adsorption test was peformed to determine the optimum reaction condition, which was 15% wood waste for mixing ratio and 2 hours for reaction time. Using biochar generated at the optimum condition, its capability of adsorbing heavy metals (Cd, Cu, Pb, Zn, Ni) was evaluated. It was concluded that lead (Pb) was removed efficiently while zinc (Zn) and nickel (Ni) were hardly adsorbed by biochar.

• Clean Technology
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• v.23 no.3
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• pp.223-236
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• 2017

As the use of waste and biomass increases in a power generation boiler, high temperature corrosion (HTC) problems of boiler heat exchangers are becoming very important. Chlorine of the low-rank fuels is mainly responsible for the HTC issues, which typically occur in the surface of high temperature heat exchanger like a superheater or reheater. In order to mitigate the problem, various approaches have been proposed in terms of design modification, material improvement, fuel pre-treatment and additive utilization. In this study, the current state of research and development focused on the additive method was investigated.