• KSBB Journal
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• v.16 no.6
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• pp.527-532
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• 2001

Trichlooethylene (TCE) has become a widespread contaminant in air, soil, and underground water due to extensive industrial used and improper disposals. Since TCE is a suspected carcinogen and constitutes public health concerns, many treatment systems have been investigated to remove this hazardous waste. One of the most premising reactor systems for the treatment of TCE is trickling biofilter (TBF), in which monooxygenase (MO), the corresponding enzyme for initiating primary substrate oxidation, fortuitously degrades TCE via cometabolism. TCE, however, is not easily treated by simple TBF. This is mainly due to the toxicities of TCE and its degradation products to microbial film in TBF. In this paper, recent progresses on the development of bioreactor system for the treatment of TCE, especially gas-phase TCE, are reviewed. The potentials of novel biofilm reactor systems were also discussed for the long-term continuous treatment of TCE.

• Proceedings of the Korean Environmental Health Society Conference
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• 2002.04a
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• pp.91-99
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• 2002

A recent survey investigated that there were over one thousand un-controlled closed landfills(1,072 sites) in Republic of Korea. Most of these landfills were constructed before 1986. Waste management act were not promulgated at that time, so they usually do not have dranage system and leachate treatment facility. Also, considerable attention has been received to landfill leachate pollution, leachate has an adverse impact on the surrounding environment such as soil, groundwater, and water supply source. According to the result of survey for closed landfill management, it was reported that 875 sites out of 1,072sites(81.6％) have no leachate treatment facility and 630 sites out of 1,072sites(58.7％) have been used for farm lands and residence. Consequently it is hard to do postclosure care continuously in most of cases and these uncontrolled landfills have contaminated farm lands and residence. The average age of these landfills are ranged mostly between 2 to 15 years. Much time and advanced technology are needed to remediate these uncontrolled landfills, therefore the survey for present status of closed landfill sites is required and suitable treatment processes should be prepared. With this point of view, We has been investigated to find out the present status of closed landfill, problems of post management and discussed plans for remediation and reuse. Remedial actions of un-controlled landfill have been carried out the many cities since 1997 upto now. Most frequently applied technology were reuse after excavation and there were several cases to capping in the surface of landfill and to construct subsurface barriers. It is considered that landfills in use have a possibility not to be controlled because of inadequate construction and improper management. Therefore remediation of uncontrolled landfills and recovery technology should be develop continuously Especially, it has been expected that resource technology of landfill gas as a energy has some advantages in controlling odors in the site area and accelerating stabilization of landfills with the energy.

• Applied Chemistry for Engineering
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• v.26 no.6
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• pp.686-691
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• 2015

A basic research for utilizing solid refuse fuel (SRF) based on changing SRF properties (RDF, RPF) and types (pellet, fluff) is demonstrated. Physicochemical characteristics of SRF and also changes in thermal decomposition depending on combustion time and emission gas (NOx, CO, HCl, etc) concentration were investigated for applications to waste energy sources. In conclusion, RPF is easy to pelletize, and has better combustion efficiency, higher LHV, higher thermal reduction, and short combustion time because it is composed of plastic wastes homogeneously. Also, fluff type samples have better combustion efficiency, and short combustion time because it has wider exposed surface area for combustion. It can also save energy consumption for pelletizing.

• International Journal of Safety
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• v.4 no.1
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• pp.14-17
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• 2005

Recycled polyol was obtained by glycolysis of MDI-based Polyurethane(PU) rigid foam. The chemical structure of the recycled pclyol was confirmed by GC(gas chromatography) and 1H-NMR. The recycled polyol throughout the glycolysis contained liquid polyol and methylenedianiline(MDA). MDA which could cause liver cancer is carcinogenic material. TWA(Time Weighted Average.) amount for MDA in MSDS(Material Safety Data Sheets) was confined less than 0.1 ppm. The melting temperature of MDA is $92^{\circ}C$, and boiling temperature is $398^{\circ}C$. During the gylcolysis most of MDA was dissolved in liquid polyol. The probability that MDA diffuses into the atmosphere is low but there could be an absorption of MDA into skin. Furthermore because MDA is amine compound, recycled polyol which contained MDA had a difficulty in reaction control of polyurethane. Therefore reduction of MDA amount was needed strongly. In this study the elimination of MDA were performed through deamination of the recycled polyol by glycidyl ether compounds. As glycolysis was proceeded, the amount of MDA was 9.8 wt % at early stage and increased up to 14.0 wt % after 8 hours reaction. It was found that 2-Ethylhexyl glycidyl ether which contains aliphatic moiety was very effective compound for eliminating the primary aromatic amine compound :md the optimal mole ratio of 2-ethylhexyl glycidyl ether to MAD was 3. The final polyol after deamination by 2-ethylhexyl glycidyl ether has an appropriate viscosity(less than 500 centi poise) for polyurethane reaction.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.21 no.8
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• pp.1068-1076
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• 1997

Emission control of acid exhaust gases from coal-fired power plants and waste incinerators has become an increasing concern of both industries and regulators. Among those gaseous emissions, SO$_{2}$ has been eliminated by a Spray Drying Absorber (SDA) system, where the exhaust gas is mixed with atomized limestone-water slurry droplets and then the chemical reaction of SO$_{2}$ with alkaline components of the liquid feed forms sulfates. Liquid atomization is necessary because it maximizes the reaction efficiency by increasing the total surface area of the alkaline components. An experimental study was performed with a laboratory scale SDA to investigate whether the scrubbing efficiency for SO$_{2}$ reduction increased or not with the application of a DC electric field to the limestone-water slurry. For a selected experimental condition SO$_{2}$ concentrations exited from the reactor were measured with various applied voltages and liquid flow rates. The applied voltage varied from -10 to 10 kV by 1 kV, and the volume flow rate of slurry was set to 15, 25, 35 ml/min which were within the range of emission mode. Consequently, the SO$_{2}$ scrubbing efficiency increased with increasing the applied voltage but was independent of the polarity of the applied voltage. For the electrical and flow conditions considered a theoretical study of estimating average size and charge of the atomized droplets was carried out based on the measured current-voltage characteristics. The droplet charge to mass ratio increased and the droplet diameter decreased as the strength of the applied voltage increased.

• Asian-Australasian Journal of Animal Sciences
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• v.6 no.1
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• pp.139-145
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• 1993

Biogas created from animal waste is a precious energy source. A practical and successful utilization of the biogas is not easy, because there lie some difficulties in biogas production and facilities investment. In this study, the requisites for a successful biogas utilization were discussed. The production results obtained in the previous operation of anaerobic digestion plant were used for the simulation. When the slurry heating was designed for constant biogas generation, depreciation costs of the facilities amounted 1,175,000 yen per year, and biogas productions at $24.5^{\circ}C$, $30.0^{\circ}C$ and $35.5^{\circ}C$ were $16.8m^3$, $17.6m^3$ and $25.1m^3$, respectively. Removal ratios of organic matters were not so high. At $35.5^{\circ}C$, energy value of the biogas produced was estimated 125.5 Mcal per day, and the following heat loss (y Mcal/day) was brought about by the temperature difference ($X^{\circ}C$) between the digester and atmosphere; y = 0.769X - 5.375. The costs of biogas production per cow were assumed to decrease according to enlargement of feeding scale, especially on scales of more than 30 cows. On recent levels of costs and prices of energy in Japan, they were nearly equal to 2 to 3 fold of the price of municipal mixed gas when a anaerobic digester was compulsorily heated and kept at $30.0^{\circ}C$ or $35.5^{\circ}C$.

• Asian Journal of Atmospheric Environment
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• v.12 no.1
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• pp.37-46
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• 2018

The Minamata Convention on Mercury entered into force on August 16, 2017. It requires Parties to the Convention to control and, where feasible, reduce mercury emissions from the listed sources. To implement the Convention, Japan amended the Air Pollution Control Law and added clauses that force operators to control their mercury emissions below emission limit values (ELVs). The ELVs have been established separately for new and existing sources, targeting the source categories listed in the Convention: coal-fired boilers, smelting and roasting processes used in the production of non-ferrous metals (lead, zinc, copper and industrial gold), waste incineration facilities and cement clinker production facilities. The factors used to establish the ELVs include the present state of mercury emissions from the targeted categories as well as the mercury content in fuels and materials, best available techniques (BATs) and best environmental practices (BEPs) to control and reduce mercury emissions and ELVs or equivalent standards to control mercury emissions in other countries. In this regard, extensive data on mercury emissions from flue gas and the mercury content of fuels and materials were collected and analyzed. The established ELVs range from $8{\mu}g/Nm^3$ for new coal-fired boilers to $400{\mu}g/Nm^3$ for existing secondary smelting processes used in the production of copper, lead and zinc. This paper illustrates the ELVs for the targeted source categories, explaining the rationales and approaches used to set the values. The amended Law is to be enforced on April 1, 2018. From future perspectives, checks of the material flow of mercury, following up on the state of compliance, review of the ELVs and of the measurement and monitoring methods have been noted as important issues.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.10
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• pp.4302-4307
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• 2011

Recently, various technologies for the fuel efficiency improvement are being developed. The purpose of this study is to evaluate the heat exchanging performance of a exhaust heat recirculation device and to propose a model with optimized performance. The device has been designed to warm up engine coolant as quickly as possible using wasted exhaust heat. To achieve these goals, heat transfer characteristics has been analyzed using CFD for the flow direction effect and in/out location effect of coolant. A method improving the effectiveness of heat exchange has been proposed. As a result, the highest efficiency in heat exchange was observed on condition that exhaust heat affects the coolant directly with a separate flow path between exhaust gas and coolant and that coolant flow rate is relatively low.

• Resources Recycling
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• v.7 no.2
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• pp.16-22
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• 1998

Recently, the new technology for the recycling of waste plastics as an alternative he1 of blast furnace ha been developed. In this shldy, the test of plastics injection into a tuyere af the foundry blast furnace were carried out. The injection rate of plastics far this tcst facility war expressed as follows, ${W}_{s}=0.265\frac{{delta}PA}{U}_{g}$, where. Ws, AP, A and Ug are plastic conveying ratc (kgisec), pressure drop between feed hopper and blaqt pressure (alm), cross sectional area of conveying pipe (mi) and superficial velocity of transport air (mhzc) respcctiuely. From the results of semi-continuous test operation during 96 hours, the replacement raho mned out to be 1.38 according to the injection rate of 6. 4 kg-plasticsit-p. With increasing the rate of plaslics injcchon, the content of hydrogen in top gas became increased and the brick temperahlre at bzlly was also increased due to Lhe changes ot the combustion zone shape.

• Korean Journal of Environmental Agriculture
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• v.25 no.3
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• pp.247-256
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• 2006

This study has been conducted for the process of food wastes disposal using surplus capacity of established sewage treatment plant by co-digestion of fermented food wastes and sewage sludge after thermophilic acid fermentation of food wastes. The co-digestion of thermophilic acid fermented food wastes and sewage sludge was performed by semi-continous method in mesophilic anaerobic digestion reactor. It showed great digestion efficiency as the average SCOD and VS removal efficiency in organic loading rate 3.30g VS/L.d. were 74.2% and 73.6%, and the gas production rate and average methane content were 0.440 L/g $VS_{add}.d$ and 66.5%, respectively. Based on the results of this study, the co-digestion of thermophilic acid fermented food wastes and sewage sludge in sewage treatment plant is able to improve treatment efficiency of anaerobic digestion reactor and to dispose food wastes simultaneously, and was proved excellent economical efficiency comparing with any other treatment methods.