In recent years, ash-melting plants were constructed in municipal solid waste treatment of facilities. There are few cases of simulation analysis that can be applied for the prediction of chemical elements behavior in both gaseous phase and slag phase in the melting process. The simulation trial by using thermodynamic equilibrium calculation software, Fact Sage, was conducted corresponding to actual pilot plant operation. The simulation results showed the possibility that can be applied practically for designing of melting furnace and process due to the operating condition and the components of incinerated ash.

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Plasma type ash melting is increasing attention as the method of volume reduction, detoxification and recycling of incineration ash from municipal refuse. This paper describes operation results of plasma type ash melting furnace in Koyamagawa Clean Center that was completed in March 2000. The operation results have clarified (1) the material balance and element balance on ash only melting, (2) the heat balance and the relationship between ash feeding rate and plasma power consumption rate on ash only and fly ash mixed melting, (3) the plasma torch electrode lifetime and wear speed.

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In the pyrolysis gasification and melting process of municipal solid waste (MSW), the ash is melted and the molten slag is produced in the high temperature combustion chamber by the calorific energy of the MSW. Utilization of the slag enables reduction of the amount of landfill in large quantity, and also contributes to the establishment of social recycle system. Aiming at the establishment of practical utilization method of the slag produced at Yame Seibu Clean Center, we conducted investigations listed below and confirmed that the slag can be utilized as civil construction materials such as fine aggregate for asphalt. Investigations were made upon (1) chemical properties of the slag, (2) leaching properties of heavy metals from the slag, (3) physical properties of milled-slag, and (4) environmental assessment of the slag utilization and follow-up survey on quality of asphalt pavement surface.

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A new environment-compatible system has been developed using waste plastics as fuel substitute in the melting furnace. From the experiments employing full-scale plants, the following results were obtained, 1. Fossil fuel consumption was significantly decreased in the experiment where mixture of waste plastics and incineration residues were treated, leading to the reduction of CO_2 emission to the environment. 2. Dioxin related compounds such as bromined dioxins contained in plastics used in home electric appliances were almost completely destroyed under high temperature conditions.

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Ash melting furnaces using combustion are used to treat incineration residue. The improvement of running costs is being required for the furnaces, because a great quantity of energy is being consumed in them. Lower energy consumption in the IHI burner melting furnace was achieved by both reduction in size of the furnace and utilization of residual carbon within the residue. Such an improvement is attributed to the high intensity combustion. In this study, the ratio of combustibles in the residue was varied from 0% to 67% by adding the coal and using a thermal decomposition product. As the ratio of the combustibles was increased, fuel consumption reduced. When the ratio of combustibles was above 41%, no fuel was necessary without the influence on melting performance. Also the relationship between the reduction in fuel consumption and the combustion phenomenon has been discussed.

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The chemical states of Pb, Cu, Zn contained in bottom ash or fly ash from MSWI (Municipal Solid Waste Incineration), as trace elements, were investigated using X-ray absorption fine structure (XAFS). As to bottom ash, it was suggested that Pb and Cu in the ash mainly exist as oxide (II) state. It was also thought that the chemical state for a part of Cu is oxide (I). On the other hand, Zn in the ash was thought to exist as mixture of other chemical states except for oxide (II), despite recognizing the existence of oxide (II) in part. As to fly ash, Pb, Cu, Zn in the ash were thought to exist mainly as oxide (II). It was also suggested that a part of Cu and Zn would be chloride.

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Gasification melting system is necessary for recycling and volume reduction of solid waste. however, many explosions accidents are caused by combustible gases filled in shredding or gasification melting process from gas cylinder and spray-can mixed within bulky waste. In this experiment, inhibition of ignition of mixed fuel composed of C_3H_8,CO and H_2,N_2 or CO_2 as the inert gas is analyzed using a spark plug as the source of ignition. As a result, 1) in waste grinder a lot of attention is needed for DME, because the ignition area of DME is larger than that of C_3H_8 and CH_4,2) according to the ignition limit calculated by Le Chatelier's formula, the security is ascertained at Pyrolysis Furnace, 3) the ignition limit is valued by the pace of increase of temperature and the product of organic radical and O containning radical.

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Recently, by proper processing of waste and improvement in recycling technology, the waste processing system has shifted to the resources circulation type We intend to operate the evaluation of the environmental load with the use of LCA method We use the Environmental Load Point (ELP) for index. In order to evaluate the influence that change of the quality of garbage resulting from change of a waste processing system has on the quality of excretions, we examined the allocation.

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We have developed new technology that can reduce the size of ballistic separators (NKK-BASEP) without deteriorating sorting performance. NKK-BASEP can efficiently sort a variety of waste plastics according to their form. We are also using this machine for a presorting process in order to reduce the manual sorting process at recycling plants. This paper will provide an analysis of this new technology and test results.

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Pyrolysis Char (PC) was activated with H_2O using a small rotary kiln type reactor to produce Activated Char (AC) for dioxin removal. Dioxin adsorptivity of AC was estimated by the amount of anthracene adsorbed on it at 168℃, Q_ANT. The Q_ANT value of AC produced from PC was 46% of Q_ANT value of a commercial activated carbon used for practical dioxin removal. The pore distributions of AC before and after anthracene adsorption showed clearly that AC keeping 1∿10nm pores are suitable for dioxin adsorption.

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It is important to approach and achieve sustainable society. Therefore it is required to develop and establish recycling technologies of waste products. Unfortunately, composting, incineration and landfill has not been widely accepted in Japan. it is urgently required to develop optional technologies. We have been proposing "Carbonization", The most important merit of carbonization is redution of weight, volume and false odor, however, it requires energies. It is quite important to theck and reconfirm Dioxin exhaust, The authors clarifeid that carbonization plant does not releasedioxin above the limited standard. It is expected for carbonization plant to reduce gaseous temperature below 850℃ for reused

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Sapporo Plastic Recycle Corporation has been operating a commercial waste plastic liquefaction plant, over two years safely since April 2000,when the containers and packaging recycling law on plastic packages was introduced in Japan. During this operation, we encountered initial troubles such as corrosion, blockade caused by HCl gas generated from PVC, and organic acid generated from PET, but cleared them one by one, and achieved continuous operation favorably. We solved this problem caused by organic acid generated from PET by adding alkali into the process. High conversion rate of oil from waste plastic was achieved by special designed degradation contrivance that is rotary kiln type with triple vessel structure. We would like to promote feedstock recycling by the product oil of this process to oil refinery first of all.

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This paper describes the outline of the new method for ash treatment, ash roasting. Ash from incinerator includes various pollutants. We must treat heavy metals and dioxins for ash recycling. Heavy metals of ash, lead, mercury and cadmium for example, volatilize to gas through roasting furnace. Dioxins is almost destroyed at high temperature over 1000℃. Demonstration testing verified that (1) leaching of heavy metals from ash can be decreased below standards of leaching from soil, (2) efficiency for dioxins decrease is over 99%. We will continue to expand the application of the ash after roasting.

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New PET chemical recycling process was developed and demonstrated in the 15kg/hr pilot testing, which can recover the terephthalic acid and ethylene glycol from post-consumer PET bottles. The developed process consists of aikaline depolymerization of PET to monomers and crystalization and purification of TPA. Through the pilot testing, it was confirmed that the recycled TPA can be used for food-container according to the FDA analysis evaluation and economical feasibility study of the commercial plant showed the competitiveness to conventional material recycling plants.

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A PCB (polychlorinated biphenyls) detoxification plant is composed of "pre-treatment process "and" decomposition process". Authors proposed the UV (ultraviolet rays)/Catalyst method by which the reaction is performed at a low temperature and an atmospheric pressure as a decomposition process and the thermal recycling using dechlorinated oil is proposed. The basic experiment on the decomposition characteristic of the UV/Catalyst method was carried out concerning PCBs contaminated by unexpected impurities such as solvent for washing and organic chemicals like pyroligneous acid. Even if there is contamination, PCBs were decomposed experimentally below the level which is less than PCB standard by UV/Catalyst method. This study showed the validity of the application of UV/Catalyst method for PCB detoxification plants.

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We developed the fibrous catalysts which had high activity in decomposition of organic chlorine compounds and reduction of NO by NH_3. The catalyst fiber composed of V_2O_5 and TiO_2 exhibited favorable structural properties (large specific surface area of more than 200m^2/g and large pore volume of more than 0.20(cm)^3/g) and capability to stabilize V_2O_5 in a well dispersed form up to high loading. A catalytic bag filter was produced by placing a layer of the catalyst fiber within a nonwoven fabric of heat resistant polymer fiber.

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Quantum chemistry calculation have been applied to estimate the catalytic activity of new oxidative decomposition catalysts for Dioxins. In order to select the screening index, it was investigated that the correlation of DFT calculation results of some properties of simple molecular models for some metal oxide catalysts and experimental results of catalytic activity for them. The binding energy between a metal atom and an oxygen atom of the models was found to be the most suitable to estimate the catalytic activity of the metal oxides for oxidation of Dioxins.

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To examine the possibility of using the TOX (Total Organic Halogen-an alternative index of DXNs) as an operational management of the DXNs reduction control, we have studied what relationship exists between DXNs and TOX of the exhaust gas from an incineration facility in terms of the distribution of combustion air, the injection volume of activated carbon, and the BF entrance temperature. We consequently have found that the data from both DXNs and TOX show the same trend. We also have investigated the relationship between DXNs and TOX at the facility where the new type of DXNs absorbent is used, and have confirmed that the relationship is different between new type of DXNs absorbent and the traditional activated carbon.

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This Paper describes the reduction of dioxins and other components with active carbon tower. These tests have been carried out at actual fluidized bed type incineration plant using bench scale equipment. The reduction rate of dioxins have kept after 3000 hours test. Dioxins concentration of the adsorber outlet flue gas (0.0015ng-TEQ/Nm3) was lower level than Japanese regulation (0.1ng-TEQ/Nm3) Active carbon tower is effective for reduction of dioxins and other Chlorinated organic compounds (ex. Hexachlorobenzene, Polychloronaphthalene)

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We have developed a system that directly decomposes dioxins in the exhaust gas by spraying activated water prepared by mixing ozone and hydrogen peroxide. Through a dioxin decomposition test in which the exhaust gas of a small incinerator was used as test exhaust gas, we verified that it would be possible to decompose the dioxins to one part per several hundred by feeding the ozone and hydrogen peroxide at the proper rate. The test result showed good coincidence with the calculated data forecasting decomposition of dioxins.

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In Europe the water cooled grate system in MSW plant has been often required since 1993,because LHV of waste change higher. Japanese MSW plant also needs same system. So we have carried out some tests for development of water cooled grate. In low level combustion air ratio test, We got high temperature in incinerator and that leads the low level emission of dioxin. We installed water cooled grate in domestic MSW plant, and we confirm steady operation for low level LHV of waste rather than that of Europe.

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Pressurized Internally Circulating Fluidized Bed Gasifire has a gasification, a char combustion, and a heat recovery chamber in one single furnace, and has a large quantity of the circulating flow of the fluidized-bed material between chambers. PICFG the following characteristics. (1) Coal is pyrolyzed by using the combustion heat of char. Combustion of syngas can be managed in minimum. (2) Syngas from coal and char combustion gas are separately discharged from the furnace. (3) An oxidation region and a reduction region coexist in one single furnace. (4) The generated char is completely burned in a char combustion chamber. (5) The bed temperature of char combustion chamber can be controlled easily. The above characteristics can realize the stable operation and high efficiency of power generation, and high efficiency desulfurization can be obtained by the coexistance of an oxidation region and a reduction region.

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In this paper, we propose a new modeling method for stoker-type incinerators of refuse incineration plants in order to analyze dynamic behavior of refuse combustion process and refuse movement. The refuse incinerator model is represented by a mathematical model taking account of moving, drying, pyrolysis, gasification, and combustion of refuse, It can simulate the dynamic behavior of refuse combustion process and refuse movements at the change of running commands, e. g. refuse inputs, combustion airs, and stoker movements.

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Refuse incineration plants (RIPs) are required to reduce concentration of dioxins in the exhaust gas and recover thermal energy from waste gas efficiency. It is very important to keep the combustion stable to realize these items. Therefore, the operators have to keep their operation skills highly. We have completed the development of a training simulator for new-type (parallel flow) refuse incineration plants to assist the operators skill up effctively. In this paper, we reported the configuration of the trainining simulator. Furthermore, the modeling method of combustion for parallel flow incineration plants and the field operation simulator based on virtual reality (VR) technology.

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High-Temperature Air Combustion Technology is an attractive method for producing surplus electric power and reducing environmental disruption materials such as NOx and dioxins especially in combustion process of Municipal Solid Waste (MSW) incinerator. The objective is to develop an energy-saving system for the MSW incinerator and to lower the emission pollutant. The experimental study is carried out systematically with simulated MSW furnaces (500kg-waste/h) to study the thermal degradation, the distribution of temperature and gas concentrations in the furnaces. Blowing the mixture of high temperature air and the flue gas to the primary combustion space brings extremely stable combustion. Moreover, it reduces not only the NOx, CO and the other toxic products, but also more than 20% of the excess air.

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High-temperature air combustion technology is applied to produce surplus electric power and reduce dioxins, NOx and CO in combustion process of a stoker-type MSW (Municipal Solid Waste) incinerator. The macro-patterns of flow and combustion are analyzed numerically with an approximate combustion analysis code using physical model. Present simulation data, general distributions of the temperature, the velocity, and the chemical species, were approximately related to the experimental data measured using a simulated MSW incinerator. We found that blowing mixed gas of high-temperature air and exhaust gas to combustion beginning space was effective for the decrease of air for waste combustion.

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Low air ratio combustion, one of the most important technologies in "the Next Generation Stoker Incinerator" was studied in two MSW incineration plants. In plant "A" with a capacity of 130t/24h, air ratio was reduced to 1.37 at the economizer outlet by optimization of combustion control. Higher exhaust gas temperature due to the low air ratio realized a low dioxins level of 0.00056ngTEQ/m^3_N at the stack inlet with a negligible CO increase. In plant "B" with a capacity of 50t/24h, a low air ratio of 1.35 enabled 20% exhaust gas reduction using FGR (Flue Gas Recirculation). As the exhaust temperature was kept the same as conventional operations in this test, dioxins level was also unchanged. However remarkable improvement was obtained in NOx concentration with a reduction of 45% compared with conventional operations.

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Ebara Corporation and UBE INDUSTRIES, LTD. have jointly developed a pressurized tow-stage Gasification system, named EUP, for the chemical recycling of plastic wastes. This system, whose main components are a low-temperature fluidized-bed gasifier and a high-temperature, swirling-type slagging gasifier, degrades plastic wastes into hydrogen and CO, which are in turn recovered and to make ammonia at an adjacent chemical plant. The treatment capacity of this system, 30t/day in the beginning, is increased to 65t/day in this fall, thus enabling an annual treatment of 20-thousand tons. the following outlines this system and its operation.

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We have newly developed contaminated soil remediation systems using indirect heated kiln and direct heated kiln which were originally developed for industrial waste treatment. The type of the kiln is decided due to the kind of contaminants. The former is applicable for the remediation of VOC or metals with low melting point. The latter is for metals with high melting point. Using the existing kilns, several remediation tests have been conducted and good results have been obtained for the soils contaminated with oil, VOC and heavy metals. We will continue to study for the practical application of these systems and the construction of the first utilizing plant with large capacity.

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In the conventional method, drums containing dangerous organic solvents are emptied by hand and the contents only are incinerated. This work is time-consuming and sometimes dangerous. Our company introduced a new system to Japan, in which drums and their contents are shredded safely in a nitrogen atmosphere and then incinerated. This paper introduces the concept and running conditions for the drum shredding and incineration feed system.

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A Pyrolysis and melting process is drawing attention as the next-generation waste treatment technology that meets such demands. In 2000,the first fluidized-bed Pyrolysis and melting system for MSW (capacity : 30tons/day×2) was constructed at Cyubu-Kamikita Clean Center in Aomori prefecture, Japan and has been operated. The present paper gives a recent operation report and an outline of plant control system for the first fluidized-bed Pyrolysis and melting system, including dioxins emission.

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We have conducted a demonstration test of a new-generation waste incineration plant embodying advanced combustion technology that reduces the amount of exhaust gas by means of combustion under low air ratio, and simultaneously controls NOx, CO and DXNs. At the air ratio of 1.3,the ignition loss was kept at the level of conventional furnaces whereas the amount of exhaust gas was reduced by 20% and NOx by 30%. The average CO concentration was below 1ppm while its peak was kept under 20ppm, and the total DXNs emission was cut down by 60%.

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In this study, in order to raise the accuracy of gaseous combustion simulation in a stoker type incinerator which is used widely and to comprehend the characteristics of primary combustion, especially waste combustion, the model (waste combustion model) which imitates the combustion process in a waste layer was developed, and experiments of gas concentration and temperature measurement near the waste layer were conducted in the real incinerator for the purpose of the basic data collection for this model verification. The waste combustion model enables to predict the mixing process of waste and mass reduction process by the vaporization of moisture, emissions of volatile matter, and reactions of fixed carbon. Also, the characteristics of waste combustion at the drying stage and burn-out stage were clarified in the experiments.

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In order to clarify the thermal decomposition behavior of urethane RDF (Refuse Derived Fuel) and wood chips, the pyrolysis experiments were performed under two isothermal conditions, which are 500℃ and 600℃ respectively employing a bench scale facility. Effects of steam injection were also investigated at the temperature of 600℃. The time change of the pyrolysis gas composition was measured. It was found that the High Heating Value (HHV) of pyrolysis gas increases with increasing the pyrolysis temperature, and the peak valueappears at the early stage of the pyrolysis. It was also demonstrated that steam can significantly facilitate cracking of high molecular compounds and decompose char into H_2,CO and CO_2,especially in the case of wood chips, where about twice gas yields was successfully obtained by steam injection.

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To plan a apparatus using microorganisms entrapped in PEG for removal of nitrogenic compounds, the effect of operating conditions for denitrification was examined. As operating conditions, flow rate, and operating mode (continuous or un-continuous operation) were determined. The most suitable condition of flow rate, ON-time and OFF-time of un-continuous mode were found. And it became clear that un-continuous mode has twice ability of denitrification than continuous mode, based on supplied energy.

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The ultrasonic sterilizing method is environmentally safe because of using non-chemicals. We have made a prototype of an ultrasonic sterilizer which induces cavitation utilizing the squeeze-film effect. Our previous experimental results shows that the prototype called "the ultrasonic sterilizing cell" can efficiently inactivate Cryptosporidium oosysts. The ultrasonic sterilizing cell can treat only a small amount of water, but the cost of treatment is much lower than the cost of the conventional ultrasonic treatment of water. For the treatment of a large amount of water, the specifications of water treatment systems consisting of the cells in series and parallel are theoretically investigated from the view point of reaction kinetics. There is a probability that a few kilowatt system will be able to treat about 100m^3 per day of water contaminated by Cryptosporidium oosysts with high efficiency. The system is expected to treat filter backwash water.

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In order to achieve an efficient and economical advanced drinking water treatment system, relationships between some operational conditions, membrane filtration flux and water qualities were examined by using pilot plant, including unit processes of ozonation, ozone resistant microfiltration (MF) module and granular activated carbon (GAC) tower. From the experimental results, it became obvious that it was necessary to keep residual ozone concentration of more than 0.3mg/L on the membrane surface in order to obtain a high membrane filtration flux. The long term running test was carried out at the flux of 5m^3/m^2/day in the condition of maintaining residual ozone concentration of 1mg/L on the membrane surface with ozone dosage of 2 to 6mg/L. Moreover, quality of the produced water from GAC tower constantly satisfied the Japanese drinking water standard, and removal ratio of odor-causing substances such as 2-MIB and geosmin was more than 99%.

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This paper describes an experimental study for the purpose of water quality improvement on wastewater (e. g. rapid sand filter backwashing drainage) recycling system in water purification plant, combined roughing filter and tank-submerged ceramic membrane filtration. Consequently, in this system, it was stably demonstrated that high removal rate of suspended solid and metal, such as iron, manganese aluminum and so on. And, membrane process could perform stable operation with membrane filtration flux 0.8m^3/m^2/day. Moreover, by arranging a sludge sedimentation zone at the bottom of membrane tank, the sludge concentration with the surroundings of the membrane was kept low, and cake accumulation on membrane surface was reduced. In the result, about 4∿5% of concentrated sludge was able to be obtained stably.

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The rotating membrane separator was operated to thicken the sludge from water treatment plant and its performance was examined through about 1 year experiment by the pilot scale. The target concentration of thickened sludge was set on 4%. The rotating membrane separator could thicken the sludge to the target concentration very stable, and be operated with a water flux of 0.6m/d for 3 months without any chemical membrane cleaning. It was found that the interval of chemical membrane cleaning was related with integrated filtrated water volume; therefore a water flux could be designed as the frequency of chemical cleaning.

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We experimentally investigated the decomposition dioxins and endocrine disrupting organic compounds in the landfill leachates by ozone/ultraviolet irradiation (O_3/UV), one of the advanced oxidation process. As the result of this study, the dioxins were decomposed to over 90% by O_3/UV. The concentration of dioxins was less than the environmental criterion. The decomposition rate of bisphenol A and benzophenone were over 90%, and the concentrations of those were below 0.1μg/L. Therefore the dioxins and endocrine disrupting organic compounds were treatable simultaneously.

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Owing to the development of sewage treatment system as a countermeasure for daily waste water, the amount of sludge generated in sewage treatment facilities has been increasing, and it becomes more difficult to find enough landfilling site. Carbonization technology of sewer sludge attracts a great deal of attention as one with promising sewer sludge processing technology. Then, usage of carbide is an important equation. Recycling use at municipal solid waste system is raised as one of the uses of carbide. Here, We examined on effective use of carbonized sewage sludge in municipal solid waste system. This paper describes the effect as a deodorant, the facilitatory effect of the precipitation in a gravity thickener, the gas evolution facilitatory effect in methane fermentation processing, the removal of water effect of sludge, and the effect at the time of membrane processing.

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In the submerged- type membrane separation equipments, membrane bioreactors or membrane separation drinking water production plants, air scrabbling in many cases plays a major role in the membrane surface cleaning. This study is aimed at elucidating mechanism how rising air bubbles induce shear stress. Shear stress acting on a vertically set flat sheet is directly measured changing airflow rate and bulk water viscosity. Effect of air flowrate and bubble diameter on shear stress was investigated. Time-series data of shear stress variation working on flat-sheat membrane surface caused by bubble flow showed intense fluctuation, which might be caused by the behavior of rising bobbles. Calculating time-averaged value plus 3 times of standard deviation for each time-series data as "maximum" effective shear stress to detach substances off membrane, it was shown that higher viscosity liquid can give higher effective shear stress, which tend to show plateau if air flow flux is more than 1.3cm3/cm2/s.

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The purpose of this study is to reuse the methane fermentation treated water to the hydroponics. After the fermentation of the mixed slurry between a cattle waste and garbage, the mixed slurry was dewatered. The filtered water was used as the liquid fertilizer for the experiment of the hydroponics. It was understood to be able to use filtered water for the hydroponics by diluting it with the water of the fixed rate. The nutrient medium of filtered water showed the effect equal with a nutrient medium on the standard KASUGAI liquid. In addition, this nutrient medium was suggested that there be an effect of the evasion medicine on the noxious insect.

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Recently, contamination of the road place-along-the-route atmosphere of a city part is aggravating. In this research, it considered that such a pollution area was the fixed generation source of toxic substance, and the purification system using water absorption of NOx, SPM was examined. As the result of an experiment, as for NO_2,75% of rate of removal, and, as for SPM, 90% of that was checked. From this result, although this system had the removal performance equivalent to the existing removal system, it was checked that it is necessary to raise processing efficiency towards utilization.

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We experimentally evaluate a performance and exhaust emissions of a single-cylinder, four stroke direct injection diesel engine operating on diesel fuel containing 50% volume waste food-oil (Blend 50), waste food-oil containing 50% waste polystyrene pyrolysis oil (Blend PS), diesel fuel containing 30% and 40% volume waste polystyrene pyrolysis oil (Blend3P, 4P), soybean oil methyl ester (VDF) and Low Sulfur Diesel fuel (LS Diesel fuel). The combustion characteristics, emissions such as NOx, CO, HC, HCHO, O_2,CO_2,smoke, particle size distribution and first stage durability test are compared with the case of JIS#2 diesel fuel. Experimental results indicate that the Blend 50 and VDF are usable as alternative fuel for diesel engine and the manufactures of VDF and Blend 50 are available for a treatment process of the waste food-oil. The Blend PS is unsuitable for the diesel engine because carbon deposit heaped up combustion chamber with the progress of operating hours. So, The Blend PS need to reduce the waste polystyrene pyrolysis oil.

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Combustibility of petroleum was investigated with high temperature air combustion technology. Ultra low NOx emission (∿10ppm) was achieved both for the kerosene and heavy oil A as fuels using a 0.4MW class test furnace. Thermal NOx was extremely reduced as decreasing the air ratio and fuel NOx was also reduced when the combustion was conducted at low oxygen concentration. Introducing the high temperature (∿1000℃) steam could decrease the NOx emission. As decreasing the air ratio, the flame was enlarged and flameless oxidation was observed. Under the low NOx combustion condition uniform distribution of temperature and chemical species were confirmed.

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PAH production of counterflow diffusion flame has been investigated experimentally. In particular, effect of variation of flame characteristics such as flow stretch, stoichiometric mixture fraction, and molar stoichiometry, on PAH production is discussed in the present study. PAH production is strongly correlated with the flow stretch. For larger flow stretch condition, PAH production is clearly enhanced. Effect of stoichiometric mixture fraction variation is also clarified. To increase the stoichiometric mixture fraction reduces PAH formation. A simple numerical analysis for counterflow diffusion flame with GRI-Mech shows that those results are reasonably explained based on the laminar flamelet concept. Concerning the formation mechanism of measured PAH, reaction path of benzene and PAH via propargyl has a key roll in the present experimental condition.

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This paper describes the result of field measurements of nitrous oxide (N_2O) emission from fluidized bed sewage sludge incinerators. Continuous monitoring of N_2O were done for 4 incinerators in 7∿14 days for each incinerator. N_2O emission was much changed with operation condition of incinerator. This results suggest that determination of N_2O emission factor by grab sampling or short term measurement may have low certainty. N_2O emission was almost determined by the free board temperature in the incinerator. It is possible to estimate the N_2O emission by the record of temperatures of incinerators. Seasonal difference in N_2O emission was observed in small capacity incinerator due to the change in free board temperature. Incinerators with the higher incineration capacity showed the higher N_2O emission factors. Emission factors obtained laid between 3700∿6400 g-N_2O/t- dry sludge. This value was much larger than the value published on "Good Practice Guidance and Uncertainty Management in National Greenhouse Gas Inventories" by IPCC.

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Combustion experiments in a laboratory-scale fluidized-bed reactor were performed to elucidate the effects of combustion temperature on PCDD/Fs formation during incineration of model wastes with polyvinyl chloride or sodium chloride as a chlorine source and copper chloride as a catalyst. Each temperature of primary and secondary combustion zones in the reactor was set independently to 700℃, 800℃, and 900℃ using external electric heaters. The PCDD/Fs concentration is reduced as the temperature of the secondary combustion zone increases. It is effective to keep the temperature of the secondary combustion zone high enough to reduce their release during the waste incineration. On the other hand, as the temperature of the primary combustion zone rises, the PCDD/Fs concentration also increases. Lower temperature of the primary combustion zone results in less PCDD/Fs concentration in these experimental conditions. This result is probably related to the devolatilization rate of the solid waste in the primary combustion zone. The temperature decrease slows the devolatilization rate and promotes mixing of oxygen and volatile matters from the solid waste. This contributes to completing combustion reactions, resulting in reducing the PCDD/Fs concentration.

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Activated carbon for dioxins removal from flue gas of municipal solid waste (MSW) incineration plants contains high concentration dioxins. We investigated the dechlorination treatment of dioxins in the activated carbon using superheated steam which can be gotten easily in MSW incineration plants. Laboratory scale experiments on the treatment of dioxins in activated carbon using superheated steam were performed. The following points have become clear from the experiments. Superheated steam can dechlorinated dioxins at over 350℃. Treatment efficiency depended on treatment time and temperature. The efficiency of TEQ value treatment were 22% for 15 min. and 55% for 40 min. at 350℃.

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