박은영 Eun Young Park , 정승미 Seung Mi Jeong , 김용진 Yong Jin Kim , 이동훈 Dong Hoon Lee

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Abstract

Sugar, starch and lignocellulosic biomass has been mainly used as raw materials for the production of the bioethanol. However, the sharp fluctuation of grain prices, a threat of world famine, and hardly biodegradable substance like lignin contained in lignocellulosic materials make the pre-processing of the biomass complicated in several aspects. As a result, the focus of attention has now shifted to the ``third biomass`` such as algae, which has a high value of energy recovery. In this study, a kind of macroalgae and its characteristic were surveyed and then, the physical, biological, chemical, combined, and hydrothermal pretreatments for its hydrolysis were deeply considered. Consequently, the macroalgae could be more effectively hydrolyzed at the combined process such as the hydrothermal-chemical or biological treatment, chemical-biological treatment and so on than the single process like the biological pretreatment.

Key Words

Bioethanol, Macroalgae, Carbohydrate, Hydrolysis, Hydrothermal

박재경 Jae Kyeung Park

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Abstract

After reviewing the storability of harvested persimmon fruits by using food-waste compost, it was hard to find an improvement of storability in room temperature, but the hardness of the fruit remained quite long when treated by foodwasted compost and stored in low temperature. So, it is decided that the use of food-waste compost doesn`t influence the fruit`s storability in room temperature, but it can influence persimmon fruits` physical properties and component significantly in low temperature. The result was shown that there was no differences on composition of persimmon fruits by food-waste compost and maintaining hardness at room temperature, but at low temperature, the composition of persimmon fruits was changed.

Key Words

Storability, Persimmon fruit, Food-waste compost, Hardness, Physical property

민부기 Boo Ki Min , 김재용 Jae Yong Kim

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Abstract

In this research, we tried to find a solution for problem of urban sewage treatment with coal fly ash and gypsum as industrial wastes. Furthermore, we examine the feasibility of reusing coal fly ash and gypsum which increasing amount of industrial wastes as urban sewage treatment materials and the concern for urban sewage coagulation and adsorption mechanism. The result shows that when 800 mg/L of coal fly ash sintered at 700oC are injected into urban sewage, optimum removal efficiency of CODCr is 87.3%, indicating more 5% improvement than of treating with not sintered condition. The study finds that when 1000 mg/L of gypsum are injected into urban sewage without sintering, optimum removal efficiency of CODCr and turbidity indicate 87.4% and 93.7% respectively.

Key Words

Industrial Wastes, Gypsum (FGD byproduct), Coal fly ash, Wastewater treatment, Urban sewage

박진규 , 강정희 , 정용길 , 이남훈

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Abstract

The objective of this study was to assess the affects of various solid waste landfill methods on mass balance of carbon. Four lysimeters simulated a conventional landfill (Lys-A), a landfill recirculated only fresh leachate (Lys-B), and two landfills recirculated leachate after pretreating with ASBR (Lys-C and Lys-D) were operated over 1,600 days. Lys-D was recirculated two times of pretreated leachate volume than that of Lys-C. Mass balance of carbon was calculated considering leachate and biogas production for each lysimeter. Lys-C and Lys-D showed that there was an increase of about 3 times in total amount of COD recovered as methane than Lys-A. This results might be attributable to the activated methanogenic bacteria and the high pH of pretreated leachate. In terms of mass balance of carbon, amount of carbon converted to landfill gas in Lys-B (25.20 g/kg-dry waste) was bigger than that of Lys-A (23.64 g/kg-dry waste), while carbon conversion rate to landfill gas for Lys-A and Lys-B showed 4.80% and 4.71%, respectively. It is assumed that only fresh leachate recirculation method can increase amount of carbon converted to landfill gas resulting from the biodegradation of organic carbon in recirculated leachate. However, in comparison with the conventional landfill method, this method should not accelerate hydrolysis of carbon from the wastes. Carbon conversion rate in the landfill recirculated leachate after pretreating with ASBR was increased due to accelerated anaerobic metabolism processes of the microbes. In Lys-C and Lys-D, about 5.9% of carbon was converted to landfill gas. Therefore, it could be seen that the landfill recirculated leachate after pretreating with ASBR could enhance carbon conversion to landfill gas more than the conventional landfill or the landfill recirculated only fresh leachate.

Key Words

Municipal solid waste, Landfill method, Leachate recirculation, Leachate pretreatment, Carbon mass balance

박진규 Jin Kyu Park , 이남훈 Nam Hoon Lee , 강정희 Jeong Hee Kang , 안영미 Young Mi Ahn , 정새롬 Sae Rom Jeong , 진효언 Hyo Eon Jin

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Abstract

In this study, optimization of anaerobic co-digestion for food and livestock wastes was studied by an experimental design method. A central composite design (CCD) was applied in designing experiments. Selected two independent variables for this study were initial substrate concentration and mixing rate of livestock wastes. The ranges of experiment for initial substrate concentration and mixing rate of livestock wastes were 2~10 g-VS/L and 0~100%, respectively. Selected responses were methane yield, maximum methane production rate and volatile solids (VS) removal rate. The experimental design was analyzed using a response surface methodology (RSM). Models obtained by the RSM were analyzed by analysis of variance (ANOVA). ANOVA demonstrated that the models were highly significant. Optimal conditions obtained for the models were initial substrate concentration of 2.1 g-VS/L and mixing rate of livestock wastes of 48.8%, respectively. The measured values under the optimal conditions were well in agreement with the predicted values from the models. Thus, it showed that the CCD and RSM were appropriate for determination of an optimal mixing condition in the anaerobic co-digestion process for food and livestock wastes.

Key Words

Food wastes, Livestock wastes, Anaerobic co-digestion, Response surface methodology, RSM, Methane yield, VS removal rate

민달기 Dal Ki Min , 황용우 Yong Woo Hwang

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Abstract

In this study, life cycle assesment (LCA) was conducted based on a functional unit of 1 ton of food waste recycling from collection and transportation to treatment processes such as feed production, composting, other recycling and incineration for 45 public food waste recycling plants. The Korean life cycle inventory (LCI) data were used for the main input material and energy. For the other input data, which could not be provided by the Korean LCI database, data of other countries were used from the database by Ecoinvent, and the strength of food wastewater for LCI DB was divided low and high concentration. In case of low strength of food wastewater, environmental impacts were suggested incineration, composting and feed production in the order, where collection and transportation were identified as the major influencing factors by contribution analysis and sensitive analysis. Contrary, in case of high strength of food wastewater, environmental impacts were suggested composting, feed production and incineration in the order, where treatment of food wastewater was identified as the major influencing factor. Therefore, discharge volume as well as concentration of food wastewater was found to be important parameter of the LCA.

Key Words

Food waste & recycling plant, Concentration of food wastewater, Life cycle assessment, LCI database, Contribution & sensitive analysis

이상훈 Sang Hoon Lee , 최연석 Yeon Seok Choi , 정두수 Du Su Jeong

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Abstract

The waste treatment cost and energy production benefit of Wonju city RDF plant, the first RDF manufacturing plant in Korea, were investigated in this study. All plant operation data, like total weight of received wastes, produced RDF and separated rejects in processes have been fully recorded for mass balance calculation of the plant. Also all consumed oil and electricity have been recorded for energy balance calculation. The results showed that the waste treatment cost not included the RDF sales price of 25,000 won/ton-RDF was 139,316 won/ton-MSW and it went down to 128,640 won when included the RDF price in 2011. Produced RDF was 42.7% of total received waste in weight. Three components analysis by mass balance calculation of total received waste showed that Wonju city`s MSW was 34.0% of combustible, 35.0% of water and 31% of incombustible respectively. Energy effect was found that total amount of produced energy was about 4 times more than that of consumed energy. Analysis data for 5 years since 2007 were summarized and shown in this study.

Key Words

MSW RDF, Plant operation, Waste mass balance, Energy consumption

배재근 , 연성모 , 조원택

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Abstract

This research evaluated the environmental impact of polyethylene water supply pipe which is a target of voluntary agreement by Waste Charge System using Life Cycle Assessment (LCA). When analyzing the contribution of each impact category to the environmental score, resource depletion had the highest contribution at 57% and it was followed by global warming with 35% of contribution. Amongst the entire process and stage, production of raw materials, production of goods and disposal had about 60%, 18% and 18% of contribution, respectively. For resource depletion which was found to have the highest contribution, production of raw materials, production of goods and disposal accounted for nearly 77%, 11% and 7% of it, and the impact category of resource depletion which belongs to production of raw materials accounted for nearly 44% of the whole environmental score. Here, it was found that 88% of it resulted from crude oil. When analyzing the contribution of each stage to global warming that is the key issue of low carbon green growth, then, production of raw materials, production of goods and disposal showed around 38%, 29% and 28% of contribution, respectively. As the result, production of goods and disposal had higher contributions than resource depletion. Electricity used for production of goods is the major cause of global warming, and electricity used in the recycling process and incineration occupied about 65% and 36% of the disposal stage. In conclusion, we need to seek for plans to reduce the use of electricity through optimization of energy use during the production of goods and disposal, in order to establish an environmental and economical competitiveness of PE-related enterprises that are operated on a small scale.

Key Words

Ployethylene, PE, Water supply, Life cycle assesment, LCA, Recycling

최재진 Jae Jin Choi , 송진우 Jin Woo Song

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Abstract

The physical properties of sidewalk pavement material made by combining rectangular chips with urethane resin were reviewed through both an indoor test and an on-site test. To obtain the chips, forest tree by-products were crushed and then passed through a 10mm sieve. The materials that remained in the 2.36 mm sieve are the above mentioned chips. For the indoor test, the mixing ratios of urethane resin to chips, by mass, were set as 30%, 40%, 50%, 75% and 100%, respectively. Then, the mixture obtained by mixing with forced mixing type mixer was formed in an iron mold. Tests for tensile strength, elasticity and permeability coefficient were performed 7 days after forming. For the on-site test, the cross-section of the sidewalk pavement material consisted of sand filter layer, crushed stone subbase, permeable concrete base and surface layer of the forest tree chip mixture. For the surface layer, the mass ratios of urethane resin to the forest tree chip were determined to be 40%, 60% and 80%, respectively. The physical property test like the one performed in the indoor test and the skid resistance test was performed over 7 days after the completion of trial construction. According to the result of the tests, the tensile strength, GB/SB coefficients and permeability coefficient were 0.1 to 0.7MPa, 15 to 43% and 0.3 to 0.5mm/sec, respectively, depending on the mixing ratio. In addition, the skid resistance coefficient was 75BPN with the mass ratio of the urethane resin to the forest tree chips of 80%. Furthermore, it was found through the on-site test that a pavement surface with excellent surface smoothness could be obtained through the application of a construction method using an electric heat roller. It was also confirmed that the mixing ratio of urethane resin to forest trees chips needed to be 60% or more.

Key Words

Forest waste, Urethane resin, Sidewalk pavement, Skid resistance

정상현 Sang Hyun Jeong , 심성훈 Sung Hoon Shim

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Abstract

In the present study, MILD (Moderate and Intense Low oxygen Dilution) combustion technology is adopted as one of the most effective tool for reduction of NOx emission in solid fuel combustion. We tried to achieve MILD combustion using the high temperature exhaust recirculation without any heat exchanger for preheating air. High temperature exhaust recirculation is accomplished by entraining the high temperature exhaust gas to air jets at just exit of the combustion chamber. This high temperature exhaust recirculation could recirculate heat and inert exhaust gas simultaneously. MILD combustion using the recirculation of the high temperature exhaust gas is experimented to investigate the effect of low NOx emission for the recycled solid fuel of the dried sewage sludge and pulverized coal. NOx emission could be reduced drastically by using this advanced combustion technique. Maximum 68% and 57% of NOx reduction was achieved for sewage sludge and pulverized coal respectively, in the high temperature exhaust recirculation MILD combustion compared with the conventional combustion using air jet only. This type of MILD combustion makes the apparent flames of both solid fuels extremely uniform without high temperature flamelet.

Key Words

Nitric oxide, High temperature exhaust recirculation, Low NOx MILD Combustion, Recycled solid fuel

배성근 Sung Keun Bae , 김기선 Gi Sun Kim

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Abstract

To establish a reasonable resource circulation oriented society of Municipal Solid Waste (MSW), more exact and detailed information for MSW generation characteristics should be obtained. Although a municipality has generally various MSW discharge sources, a simplified generation characteristics is uniformly applied in all cases for establishing an integrated waste management system regardless of living style such as single detached house or apartment and living area such as urban or rural area. The annual average generation rate of municipal solid wastes in Changwon is approximately 0.345 kg/c·d. As the results of density analysis, the average density of urban or rural area 0.210 ~ 0.216 kg/L. The weight percent of combustible matters is on average 98.9% and food waste was major source of solid waste as 58.5%. Calorific value range from 1,620 kcal/kg to 1,680 kcal/kg at detached house and 2,780 kcal/kg to 2,980 kcal/kg at apartment. Apartment residence has higher the calorific value than detached house. In this study Changwon city was selected as a model municipality which has urban and rural area. MSW generation rate and its physicochemical properties were experimentally estimated, and then the MSW discharge characteristics of residents were also surveyed by questionnaire. Data were classified into generation source and region to identify their differences in MSW generation characteristics.

Key Words

Municipality Solid Wastes, Generation rate, Physicochemical property, Heating value

이상은 Sang Eun Lee , 김호 Ho Kim , 최창식 Chang Sik Choi , 한성국 Seong Kuk Han , 송형운 Hyoung Woon Song

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Abstract

Diverse studies are being conducted on sewage sludge treatment and recycling methods, but the demand for a lowcost treatment technology is high because the sewage sludge has an 80% or higher water content and a high energy consumption cost. For this purpose, the waste volume can be reduced and solid fuel can be obtained from the Thermal Hydrolysis Reaction (THR) that consumes a small amount of energy. The experiment was conducted at a reaction temperature of 170-220oC and maintain for 1 hour at the final temperature. According to the Capillary Suction Time (CST) and Time to Filter (TTF) evaluation, the dewater ability was good after the temperature reached 200oC and did not significantly differ at the 200oC and higher reaction temperatures. The heating value of the dehydrated solid product was 3,800-4,200 kcal/kg, and its yield rate decreased from approximately 80% to 60% with the increase in the reaction temperature. To evaluate the efficiency of anaerobic digestion, the water quality of the liquid product was analyzed based on the reaction temperature. At the temperatures of 200oC and higher, the concentration of ammonia, which increases the pH and hinders anaerobic digestion rapidly increased. From the overall evaluation of the dehydrating efficiency, solid fuel quality, and anaerobic digestion efficiency during the thermal hydrolysis of sewage sludge, it is concluded that the optimal operating temperature is 200oC.

Key Words

Thermal hydrolysis reaction, Sewage sludge, Dewater ability

이원준 Weon Joon Lee

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Abstract

Renewable energy has been focused issue in terms of green house gas (GHG) prevention as well as the sustainable development. One of the most feasible and economical ways to enhance the renewable energy production would be the biomass energy production, which is renewable in terms of carbon neutral. At present, many developed country discovered the biomass resources that will be fitted to their purpose. In Malaysia and Indonesia, palm kernel shell (PKS) was only the waste to dumping on the ground around 5 years ago, but they are exported to all over the countries as a biomass resources. The woody biomass has been the most traditional biomass resources, and their price is so high and quantity is so limited that the electric generation can`t obtain enough quantities to fulfill their renewable energy obligation quarter. Within near future, many types of biomass like rice husk pellet, coconut shell, and empty fruit bunch (EFB) pellet, will be traded commercially and imported to Korea after all. The Korean power plant company using coal try to discover the biomass resources in south. east Asia. In this study, 7 types of biomass was tested for fuel quality as well as the combustion behavior, and compared to each other. It can be found that the fuel property of biomass can be varied with the types and the combustion pattern may not be identical with respect to the types of the biomass. PKS was the very good fuel with high calorific value, but contains some chloride. Wood chips also were a good fuel property cleaner than coal in terms of emission gas. The rice straw, however was not good enough to use as a fuel.

Key Words

Biomass fuel, PKS, Waste Chip, WCF, Rice Husk, Rice Husk Pellet