이병인 Pyong In Yi , 박정한 Jung Han Park , 이상혁 Sang Hyock Lee , 미키오 카사하라 Mikio Kasahara

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Due to the various environmental problems found in these days, new approach is needed to effectuate "sustainable development" or "living together with nature" in the field of environmental research. Life Cycle Assessment(LCA) has been first introduced in Western countries as one of the efficient approaches to environmental problems. LCA is an emerging field in Korea, therefore more research is needed to utilize LCA in society and industry. Japan used LCA earlier than Korea since 1980, and applied it to many fields. Especially, LCA in Japan has been extensively used in input-output analysis in government, industry, and academy. Since Japan and korea share many similarities in industry and society, it is useful to review Japanese research trends of LCA in order to effectively applicate LCA in Korea. Thus, the purpose of this paper is to present research direction and applicate of LCA in Korea by studying LCA research trends in Japan.

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서영화 Young Hwa Seo , 신대현 Dae Hyun Shin , 이경환 Kyong Hwan Lee

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Continuous gas-phase reaction for heavy reactant, which was obtained from the degradation of waste HDPE, was investigated over zeolite Y and silica-alumina catalysts. The experimental conditions were reaction temperature at 380℃, catalyst amount of 10g, feed rate of 0.06g/min. and nitrogen flow rate of 20 cc/min. In the gas-phase reaction the fraction of heavy product sharply decreased, whereas that of light product clearly increased. Gas-phase reaction had much more formation of aromatics and paraffins, which were obtained by the cyclization and hydrogenation of olefin, than those of liquid-phase reaction. Aromatic and iso-paraffin were easily produced on zeolite Y catalyst.

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원휘준 Hui Jun Won , 오원진 Won Zin Oh , 김계남 Gye Nam Kim

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The electrokinetic apparatus for remediation of the soil contaminated with Cs+was designed. After kaolin clay was compulsorily contaminated by Cs+ solution, the remediation characteristics by electrokinetic method were analyzed. After remediation experiment, the pH of the cathode side of the soil column was increased to 12.7 due to the generation of OH- in cathode reservoir, but there was no hydroxide cesium form in the cathode side. Effluent rate from the cathode was almost constant and cesium concentration of effluent decreased with time passage. The 49% of a total of Cs+ in the column was decontaminated for 0.4 day, the 72% for 0.8 day, the 83% for 1.2 days, the 89% for 1.6 days, and the 93% for 2.1 day. Furthermore, the predicted values of residual concentration by the developed model were quite similar to those obtained from experiments.

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박승범 Seung Bum Park , 이봉춘 Bong Chun Lee

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Quantites of waste glass have been in the ride in recent years due to an increase in industrialization and the rapid improvement in the standard of living. The utilization of waste glass in concrete can cause cracking and weakening due to an expansion caused by an alkali-silica reaction(ASR). In this study, ASR expansion and properties of strength were analyzed in terms of waste glass content and fly-ash content, in anticipation of reducing ASR expansion. Using this accelerated ASTM C 1260 test of waste glass, no pessimum content was found. Furthermore, when fly-ash and waste glass were combined, there was an effect on the reduction of expansion and strength loss due to ASR between the alkali in the cement paste and the silica in the waste glass. The compressive, tensile and flexural strengths of concrete have been shown to decrease when the content of waste glass is increased. Also, when fly-ash and waste glass were combined, there was an effect on the reduction of strength loss.

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홍순진 Soon Jin Hong , 윤상국 Sang Kook Yun , 최광호 Kwang Ho Choi , 한인호 In Ho Han , 정진우 Jin Woo Choung , 이재훈 Jae Hoon Lee

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This paper presents an energy-saving cryogenic process to reclaim the rubber powder from the waste-tyres. The newly invented process is a cryogenic freezing process with use of the wasting LNG(Liquified Natural Gas) Cold Energy as freezing source of waste-tyres. LNG Cold Energy, which consists of sensible and latent heats released during gasfication process of LNG by sea water for suppling to the end users, can be used to freeze waste-tyres. In this process, LNG Cold Energy is recovered with a refrigerant(R-22) and supplied to the freezing process of waste-tyres. The fine powders can be easily obtained by applying impact energy after the waste-tyres are frozen. A pilot plant to produce rubber powders(1 metric ton per day) was constructed from this study and examined for obtaining the scale-up data. The experimental results showed that the circulation flow rate of R022 refrigerant should be 11 times for unit ton of waste-tyre freezed down to -120℃. With normal operation of the single step in crushing system, the average powder size of 2.5mm was yielded from the 1"×1" waste-tire chips, and finer powders can be produced by multi step in crushing process. The freezing temperature of the waste-tires, in order to crush them properly, ought to be under -120℃ and the freezing time should be more than 12 minutes in cold refrigerant.

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박승조 Seung Cho Park , 최성우 Seong Woo Choi , 서향미 Hyang Mi Seo

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This study has carried out the coagulation tests for tannery wastewater including high-level suspended solids and organic matters to determine the optimum pH and coagulant dosage and to characterize several coagulants for coagulation. In case of optimum pH range test, we know that multi-coagulants are not only cost-effective but also applicable from acidic pH range to alkaline pH range widely, while single-coagulant are useful in limited pH range. Removal efficiency for using of the multi-coagulants appeared more efficient than that of single=coagulant. Especially, sulfates(alum-ferric sulfate : AFS and alum-magnesium sulfate : AMS) are more effective than chlorides (alum-ferric chloride : AFC and alum-magnesium chloride : AMC). In comparison of residual turbidity related to settling time between alum and alum-ferric sulfate-magnesium sulfate (AFM), it took to 40 minutes using of alum but 5 minutes using of alum-ferric sulfate-magnesium sulfate(AFM) until constant residual turbidity are reached.

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박영목 Yeong Mog Park , 우문정 Moon Jung Wu

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An experimental study has been carried out to investigate the effects of admixtures for the highly plastic dredged soils. A series of laboratory tests were performed on the specimens of the soils with and without the waste lime(WL) and Condor SS used as admixture. It has been found that the waste lime might enhance the mechanical properties of the mixed soil; the strength was increased with increasing waste lime rate and curing time, and with decreasing water content of the soil. The waste lime was also found to have an effect decreasing settlement and permeability of the soil. The optimum mixture rate of waste lime is considered to be 20~30%. A brief consideration was made on the effect of Condor SS for the Treatment of very soft soil.

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조순행 Soon Haing Cho , 이병진 Byung Jin Lee

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The purposes of this study were to investigate the possibility to apply ammonia stripping process with diffused air method for the removal of the highly concentrated ammonia nitrogen in wastewater from hexane fermentation process and to suggest optimal operating conditions of ammonia stripping process in the consideration of treatment cost and efficiency of treatment according to operation conditions. In pH control process that was applied as a pre treatment process of ammonia stripping, use of Ca(OH)2 was very effective not only to increase pH but also to remove CODCr, T-N, T-P, turbidity and color. The optimal pH of ammonia stripping was 10/5. The reaction time to satisfy 1,000 mg NH3-N/L was 2.6, 1.6, 0.8, 0.6 hrs at 25, 35, 45 and 55℃, respectively, at the air flow rate of 20L/min. CaCO3 removal process was required after ammonia stripping since the effluent contained high concentration of CaCO3 which were produced during aeration. Capital cost and operating cost also were decreased with the increased reaction temperature and air input. In conclusion, the ammonia stripping procedure was very efficient for the treatment of highly concentrated nitrogen in wastewater from hexane fermentation process and the optimal conditions of ammonia stripping were at the pH of 10.5, the temperature of 55℃, and the air flow rate of 20L/min.

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조순행 Soon Haing Cho , 이병진 Byung Jin Lee

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The objectives of this study were to examine the applicability of ammonia stripping process for the removal of highly concentrated ammonia nitrogen in the wafer cleaning wastewater from semiconductor producing procedure and to recover removed ammonia nitrogen in the consideration of natural resource recycle. Also, the capital cost and operating cost was reviewed to suggest the optimal operation condition of ammonia stripping according to changes in the operation conditions. Using Ca(OH)2 for pH control of wastewater was superior economically to use off NaOH and ammonia stripping was possible without removal of sludge. The optimal pH of ammonia stripping was 10.5. The ammonia nitrogen was removed rapidly along with increasing reaction temperature and air flow rate. The reaction time to satisfy 800 mg NH3-N/L was 4, 2.3, 1.4, 0.9hrs at 25, 35, 45 and 55℃, respectively, with the air flow rate of 20L/min. In addition, H2O2 was removed completely, about 95% of organic nitrogen was removed, and up to 81.2% of ammonia nitrogen was recovered by ammonia stripping process. Capital cost and operating cost also were decreased along with the increased reaction temperature and air input. In conclusion, the ammonia stripping process was very efficient in the treatment of highly concentrated nitrogen in wafer cleaning wastewater and the optimal operating condition of ammonia stripping was at pH of 10.5 and temperature of 55℃ with air flow rate of 20L/min among applied operation conditions.

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진호섭 Ho Sub Jin , 황인성 In Seong Hwang , 이현경 Hyun Kyung Lee , 박주양 Joo Yang Park

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A chemical equilibrium model, MINTEQA2, was applied to predict the acid neutralization capacities (ANCs) and contaminant leaching behaviors of raw and variously aged steel slags. In MINTEQA2 simulation, steel slags were represented as compositions of chemical members, of which total concentrations were based on maximum leachable amounts from Availability test. The compositions were equilibriated with given amounts of acid in MINTEQA2 to simulate ANC test. As a result, this MINTEQA2 application can reasonably describe behaviors of ANC of slag and pH-solubility relationships of contaminants from slag with a calibration made for metal's adsorption onto fine oxide surfaces. This indicates that a chemical equilibrium model such as MINTEQA2 can be available substitute for regulatory leaching tests that frequently provide unreliable results.

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한승호 Seung Ho Han , 허형우 Hyung Woo Hur , 박종부 Jong Bu Park , 최성수 Sung Su Choi

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The effects of temperature (35 and 55℃) on methane production and removal efficiencies of organics were studied during the anaerobic digestion of food waste using two-stage plug flow reactors. The bench scale system consisted of mixing, acidification and methanization reactor. The organic loading rate and retention time of digestor were 6g VSS/L/d and 15days, respectively, on an average. At thermophilic condition (55℃), the yield of gas and methane content were 0.944 ㎥/kg VS and 63.3%, respectively, whereas at mesophilic condition (35℃) the yield of gas and methane content were 0.815㎥/kg VS 54.8%, respectively. The concentrations of CODCr, BOD and volatile solid of effluent from mesophilic digestor (35℃) were 66,600mg/L, 27,595 mg/L, and 1.79%, respectively, and those of effluent from thermophilic digestor (55℃) were 37-955mg/L, 10,908mg/L, and 1.08%, respectively. The removal efficiency of BOD was 1.48 times as high at the thermophilic condition (55℃) as at the mesophilic condition (35℃), also the 1.1 times higher removal efficiency of volatile solid was observed.

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이병기 Byoung Ky Lee , 이종신 Jong Shin Lee , 노재성 Jae Seong Rho

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This research was conducted to develop the low toxic wood preservatives recycling hexafluorosilicic acid, an industrial by-product. We synthesized copper hexafluorosilicate from hexafluorosilicic acid and investigated preservative effectiveness, property of iron corrosion and moisture regain and mechanical property for wood treated with copper hexafluorosilicate solution. It was shown from a leaching test that copper hexafluorosilicate could be removed easily from treated wood. However, by energy dispersive X-ray microanalysis for leached wood after treatment with 2wt% copper hexafluorosilicate solution, it was proved that some quantity of ingredients was retained within treated wood after leaching test. The unleached wood blocks after treatment with copper hexafluorosilicate solutions showed good preservative effectiveness against test fungi, Tyromyces palustris and Trametes versicolor. The leached wood blocks after treatment with 2wt% copper hexafluorosilicate solution maintained good preservative effectiveness against Trametes versicolor, white rot fungus even after leaching test, whereas against Tyromyces palustris, brown rot fungus, it was proved that preservative effectiveness was decreased due to leaching of leaching of ingredients by leaching test. However, it was expected that preservative effectiveness against Tyromyces palustris could be improved by treatment with high concentration solution of 3wt% or more. The distinct differences in property of iron corrosion and moisture regain between treated and untreated wood were not recognized. Futhermore, treatment of copper hexafluorosilicate was not affected in mechanical property of wood to improvement of preservative effectiveness in manufactured plywood and particleboard

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박종진 Jong Jin Park , 박진원 Jin Won Park , 최명재 Myung Jae Choi

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Characterization of the styrene recovery by using domestically ingoted waste EPS (Expandable Polystyrene) was investigated. In comparison with the non-isothermal reactor, raw material was fed to reactor maintaining constant reaction temperature. Experiments were carried out to minimize the interference of the reactor materials by using 1000 ml capacity Pyrex reactor. Experimental parameters were selected to increase amount of the produced oil and selectivity of the styrene monomer. Impact factors of the reaction include amount of feeding material, reaction temperature, types and the size of the catalysts, and reaction time. Among those parameters, the reaction temperature, time, and catalysts greatly affect on the production of styrene monomer. In the non catalytic reaction, the reactor temperature of the experiments is ranging from 350℃ to 480℃. At the optimum temperature of 450℃, the yield was 93.6wt% and 76.3wt% respectively. The initial concentration of styrene produced from decomposed oil was shown to 84.29wt% and the styrene yield greatly decreased according to the reaction time. Finally, effect of the catalyst was studied when the catalyst(BaO) was used. The oil yield and selectivity increased compared to non catalyst by 6.0wt%, 10wt% respectively under 50% conversion(at Tr=350℃). And the production yield for the size(38㎛, 150㎛) was 64.35wt%, 41.40 wt% respectively.

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성낙창 Nak Chang Sung , 장성호 Seong Ho Jang , 고현웅 Hyun Woong Kho

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Characterization of the styrene recovery by using domestically ingoted waste EPS (Expandable Polystyrene) was investigated. In comparison with the non-isothermal reactor, raw material was fed to reactor maintaining constant reaction temperature. Experiments were carried out to minimize the interference of the reactor materials by using 1000 ml capacity Pyrex reactor. Experimental parameters were selected to increase amount of the produced oil and selectivity of the styrene monomer. Impact factors of the reaction include amount of feeding material, reaction temperature, types and the size of the catalysts, and reaction time. Among those parameters, the reaction temperature, time, and catalysts greatly affect on the production of styrene monomer. In the non catalytic reaction, the reactor temperature of the experiments is ranging from 350℃ to 480℃. At the optimum temperature of 450℃, the yield was 93.6wt% and 76.3wt% respectively. The initial concentration of styrene produced from decomposed oil was shown to 84.29wt% and the styrene yield greatly decreased according to the reaction time. Finally, effect of the catalyst was studied when the catalyst(BaO) was used. The oil yield and selectivity increased compared to non catalyst by 6.0wt%, 10wt% respectively under 50% conversion(at Tr=350℃). And the production yield for the size(38㎛, 150㎛) was 64.35wt%, 41.40 wt% respectively.

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이우근 Woo Keun Lee , 심영숙 Young Sook Shim

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The disposal of MSWI(Municipal Solid Waste Incinerator) ashes has induced serious environmental problems because of their large amounts discharged. Therefore, many technologies have been studied to detoxificate, reutilize and dispose of them. In our study, we synthesized zeolite-like adsorbent with MSWI ash by means of hydrothermal processing. We use the concentration of NaOH, a reaction temperature and a reaction time in a reactor and a autoclave as principal variables. The phase of adsorbent after synthesis was identified by X-ray diffraction(XRD), and their morphology was examined by scanning electron microscopy(SEM). And also cation exchange capacity(CEC) were analyzed by ammonium acetate method. The maximum CEC value was obtained under the condition of 3N NaOH, 100℃ and 12hr reaction. Its value was 62.13meq/100g at this condition, which was 7 times higher than that of raw fly ash. The BET surface area of adsorbent lead to maximum value at the same condition. We conducted adsorption experiment to evaluate the adsorption capability of synthesized adsorbent. The experiment to remove heavy metals, such as Pb and Cu in waste water was carried out. According to the results, approximately 70% of Pb was removed at pH 7. Therefore, MSWI ashes could be used as raw material of adsorbent for heavy metals.

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이주광 Ju Goang Lee , 장영기 Young Kee Jang , 홍민선 Min Sun Hong , 김승도 Seung Do Kim , 이용은 Yong Eun lee , 강혜진 Hye Jin Kang

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This research was designed to investigate the physico-chemical properties of combustible solid wastes generated from seven highway rest areas, four highway branches, and one highway construction site. Major generation sources of solid wastes in highway rest areas are restaurant, general stores, and vending machines. Food wastes are mainly responsible for the solid wastes generated from the highway rest areas and mostly recycled for animal feeds. Combustible wastes incinerated by small-size incinerators in the rest areas are composed of papers, plastics, and food wastes representing about 90% of total incinerated wastes. Highway branches have collected solid wastes improperly dumped on highways. Wastes on the highways are mainly composed of newspapers, waste tires, and rubbers related to tires. Construction site of highway generates construction wastes like packing papers for construction materials, plastics, rubbers, and woods. Apparent densities of combustible solid wastes from rest area, branch, and construction site are 81.9, 130.3, and 117.4 kg/m3, respectively. Low heating values of combustible solid wastes from rest area, branch, and construction site, respectively, are 5,238, 6,029, and 5,363 kcal/kg which are three times higher than those of domestic municipal solid wastes. Owing to low moisture contents and high heating values, it is appropriate to incinerate the combustible solid wastes from rest areas, branches, and construction. It is, however, expected that the small-size incinerators presently operated at the highway facilities would be inappropriate to incinerate the high heating values of solid wastes. Alternatives to the small-size incinerator are: (1) consigned treatment to local governments using large-size incinerators, (2) construction of medium- or large-size incinerators at several sections, and (3) consigned treatment to private companies by paying treatment fee.

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