In the present study, the influence of residual O₂ concentration on the concentration of dioxin formation has been investigated through combustion experiments at 1073K with polyvinyl chloride (PVC) powder. The residual O₂ concentration was changed widely from 0.1vol% to 35vol% by setting the mixture ratio of O₂-N₂ gas composition and the PVC feed rate to various values.
Maximum dioxin concentration occurres at a residual O₂ of about 3vol%, and its concentration sharply decreases in proportion to the rise in the residual O₂ concentration, but the decrease in dioxin concentration becomes very gradual after the residual O₂ concentration exceeds 10vol%. On the other hand, dioxin concentration decreases in a reducing atmosphere with residual O₂ of 0.1vol% and a high CO concentration.
Under a complete combustion condition, a PCDFs finger pattern for short residence time of combustion gas at high temperature zone tends to be high concentration with increasing chlorine numbers. On the other hand, that for long residence time shows an inverse tendency to have a high concentration with decreasing chlorine numbers. In addition, under incomplete combustion condition, the PCDFs finger pattern has no special tendency for chlorine number differences. Although a long residence time of combustion gas in a high temperature zone causes to decrease in total dioxin concentration, sometimes TEQ-dioxin concentration not only does not decrease but also increases because of the increase in less chlorinated homologues by the dechlorination of more chlorinated dioxins.

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To evaluate the durability of nickel-supported commercial catalyst for use in organic waste gasification, steam-reforming experiments were conducted at 750°C by using benzene, toluene, and xylenes (BTX) as representative aromatic hydrocarbons, and then using waste wood scraps from a construction site. The catalyst characteristics were investigated based on temporal changes in BTX decomposition behavior and the composition of gases produced from waste wood.
Regarding BTX decomposition properties, the catalytic activity duration and the decomposition rate of BTX increased in order of benzene, toluene, and xylene. Moreover, results showed that the decomposition rate of BTX improves considerably when calcium oxide is located upstream of the reforming catalyst. For waste wood gasification and reforming, the produced hydrogen maintained a roughly constant concentration around 50-60 vol.%. However, about 10 h after the experiment began, the amount of produced hydrogen per unit mass of waste wood showed a slight decrease. Simultaneously, the concentrations of low hydrocarbons, aromatic hydrocarbons, and hydrogen sulfide increased gradually.

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For the development of effective utilization techniques for sugi (Cryptomeria Japonica) resources, as a novel reaction medium, superheated steam was used to extract organic substances from sugi leaves in a pressure range below saturated vapor pressure at 100~200°C. The yield with superheated steam at 170°C was about five times as high as that obtained at 100°C, and the yield also increased as extraction time and steam pressure increased. Steam with higher temperature and higher pressure contributed to enhancing the oil yield and extracting more high-molecular-weight compounds such as sesquiterpenes and diterpenes. In addition, to examine the effectiveness of the extracts obtained by superheated steam, their antimicrobial activities against 18 soil microorganisms were examined using the disk-diffusion method. Extracts obtained by superheated steam exhibited significant antimicrobial activity, especially against fungi and actinomycetes. The analysis of the chemical compositions of the extracts by GC-MS and GC-FID suggested that one or more of the monoterpenes and sesquiterpenes were the substances that were potentially responsible for such antimicrobial activity. Superheated steam exhibited some advantages in selectively extracting active antifungal ingredients from natural materials.

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This paper estimates disposal amounts and potential substance volume of video recorders, DVD recorders, video cameras, audio players (flash memory and HDD types), video games and mobile phones. It is estimated that approximately 60000tons of these types of wastes are being disposed of annually. When estimated per capita, at approximately 0.4kg/yr per capita for these waste items, the amount is relatively small in comparison to an estimation of 6.7kg/yr per capita for CRT TVs, air conditioners, washing machines and refrigerators. Waste from these small devices and equipment is estimated to contain a total of four tons of gold and three tons of palladium.
Results indicate that there is a high potential for precious metal recycling from small electrical devices and other electronic equipment. Excluding reuse, more than half of these types of equipment are being disposed of as household waste (through the municipal government). Based on a public questionnaire, about 80% of Japan’s municipal gove rnments recycle some kind of resources : approximately 90% are recycling iron and approximately 60% are recycling aluminum. It appears that precious metals are not being recycled. This paper gives several suggestions regarding what needs to be considered in order to establish recycling small electrical and electronic equipment. Hidden flow, according to the Ecological Rucksack concept, may be an important aspect to incorporate into this recycling process. E-waste is another perspective to be examined.

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A simple measurement method for medium and low volatile organic halogens (MLVOX) in flue gas at municipal waste incinerators (MWIs) and its utilization are described. 10~40L amounts of flue gas were sampled at 11 stoker-type MWIs and concentrations of organic chlorine and organic bromine were measured with barrier-discharge radiofrequency helium plasma. It was found that LVOCl gave a higher correlation to total dioxins than MVOCl. However, memory effect is thought to explain the difference in the correlating equation. Moreover, LVOCl-TEQ correlated less than LVOCl-total dioxins, because LVOCl quantified the amount of organic chlorine independent from the structure-governed toxicity. In addition, this method can be utilized to facilitate monitoring the concentrations of organic halogen in flue gas, operating gas treatment devices and observing the status of de novo synthesis.

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In the development of soil deodorization equipment, it is necessary to measure the air permeability coefficient that describes fluid flow in soil. The air permeability coefficient is an important parameter in gas advection in soil. We proposed a new test apparatus to measure air permeability accurately. In this study, three sandy soils (Toyoura sand, Silica sand, Masa soil) were used to measure air permeability. The proposed apparatus has the following advantages compared to those proposed by others before. 1) It can stop side flow by applying confined compression to a rubber cover from the side. 2) A change in the sample volume can be measured simultaneously. Although the results with Toyoura sand show that air permeability obtained using the proposed apparatus was slightly lower over the range of the suction than that measured by Kamiya et al. (2006), the proposed apparatus can be used not only for designing effective soil deodorizing equipment but also for other purposes.

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