[in Japanese]

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Landfill methane emission will continue up to several decades after completion of landfilling. Since distribution of the surface methane flux will be highly biased and gas ventilation and leachate collection systems could work as shortcut path, it is difficult to set up enough and/or proper monitoring points to obtain the whole or representative emission at a site. Moreover there is no method which can meet available labor and cost for long-term monitoring. Therefore, there is few monitoring data on methane emission especially in Japan. We are developing monitoring methods for landfill methane emission with less labor. Applicability of the laser methane detector to the closed chamber method was demonstrated at landfills in Japan and Thailand. The monitoring method of methane emission through gas well was also monitored by the landfill gas analyzer at a Japanese site.

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We have proposed a convenient monitoring method for CH4 concentration in the ambient air at the landfill sites and investigated its reliability and utility. A portable open path analyzer(POMA) was used, together with a retroreflector.The reliability of the proposed monitoring method is apparently similar to that using the the flame ionization detector hydrocarbon analyzer. The proposed method is both a convenient and practical way of monitoring the change of average CH4 concentration in ambient landfill site air in order to know the influence of landfill gas on working condition at illegal dumping sites and the degree of landfill stabilization.

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[in Japanese]

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Safety and low-cost treatment technology of low-concentrated PCB kept in large quantities in Japan is required.We developed high-activity calcium oxide that is able to treat PCB usefully in hexane.We report some informations about the mechanism of PCB treating by the calcium oxide.

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[in Japanese]

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We had already reported the PCB ELISA which reacted fairly equally to Kanechlor 300/400/500, and pretreatment method for determination PCBs in insulating oil. In this study, we improved the sensitivity of this ELISA as well as the simplicity of pretreatment method to obtain better accuracy and precision results on determination of around 1 mg/kg levels of PCB oil samples.

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[in Japanese]

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Recently, biological method is expected as an alternative remediation technique for soil contaminated with dioxins. Pseudallescheria boydii (P.boydii), which we isolated from sludge in a leachate treatment facility, is able to degrade dioxins. Regarding to P.boydii's dioxin degradation, the fundamental characteristics involving a relationship between cell growth and dioxin-degradation, and an influence of dioxins on cell growth have not ever been investigated. Modeling based on the characteristics provides an estimation of an amount of treated dioxins per cell weight, nutrient demand for degrading dioxins and time for treatment, which are useful for designing a treatment reactor. There are two purposes in this study. One is to investigate the fundamental characteristics of 2,3,7,8-TCDD(TCDD) degradation by P.boydii. On the basis of the degradation characteristics, another is to investigate applicability of the existing mathematical model to TCDD degradation by P.boydii. As a result, P.boydii has degraded TCDD with glucose by a cometabolic process. P.boydii has not been inhibited by 10ng/mL TCDD during its growing. The existing mathematical model based on the degradation characteristics was able to apply to TCDD degradation by P.boydii. A statistically reasonable agreement was obtained between the experimental and calculated data.

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[in Japanese]

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[in Japanese]

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Safety and low-cost treatment technology of PCB waste oil and dioxin analysis waste is required.We developed the calcium oxide that is able to decompose almost dioxin standards in hexane.We report the result of treatment of a dioxin analysis waste (flyash and sediment) by the calcium oxide.

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[in Japanese]

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[in Japanese]

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Leaching characteristics of hydrophilic compounds in plastic waste were investigated by content test and serial-batch leaching test. BisphenolA leached from samples gradually and continuously. On the other hand, total amount of 1,4-dioxane leached from plastic with antistatic additives by single-batch leaching test.

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In Japan, There is Law on Promoting Green procurement Purchasing and recycled materials are authorized for construction materials. In local division, there are many authorized systems for recycled material by local governments. There is no regulation for environmental impact to use recycled material for construction and usually we use judgment methods for contaminated soil (Leaching test: Japan Legal leaching Test (JLT46)). In soil environmental standards, there are 2 methods for judgment. These are leaching test (JLT46) and soil extraction test (JLT19). Soil and alternative material are similar at physical characteristics but are different at chemical characteristics. In this research, we try to test the recycled fill up material made from inorganic sludge. Recently we find that this materials release Cr(VI) and start to recovery from used site. We investigated characteristics of this material and mechanism of leaching Cr(VI) in site. In our experiment, we tried characterization tests and Dry-Wet repetition test (Environmental exposure test). This materials include much T-Cr and a part of Cr existed as Cr(VI). Cr(VI) concentration was increased by dry wet repetition. Characteristics of leaching Cr(VI) were influenced by pH.

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Melting treatment of asbestos wastes will be promoted as a matter of national policy, but a testing method for asbestos in melting treatment material is not available. Dispersion staining and X-ray diffraction method, which are applied to building materials, are difficult to apply to melting materials, because the former cannot detect very thin fibers and the latter has insufficient limit of quantitation (0.1 to 1%). Since transmission electron microscopy (TEM) can detect small and narrow fibers and identify asbestos by crystal structures and elemental compositions obtained by electron diffraction and energy dispersive X-ray analysis, it is very useful to determine asbestos fibers in melting treatment materials. Therefore, we propose and evaluate a testing method consisted of water elution of fibers from melting treatment materials and TEM determination.

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[in Japanese]

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Recently, chemical oxidation method for landfill sites has been being developed, but by-products that are hard to be detected by chemical analysis can be produced by this method. Thus, toxicity tests can be useful tools for detecting the changes. This time, acute toxicity changes of the leachate for the early-stabilization of the model landfill were monitored by Microtox™, ToxScreen-II, and DaphTox. During the test periods, leachate quality was improved and its toxicities were also reduced. Though ToxScreen-II (pro-organic buffer) was the most sensitive to the changes in the leachate quality, toxic responses of each organism to each leachate were similar except for that in PM buffer (ToxScreen-II). Combination of H2O2 and air supply to the landfill was helpful for the early-stabilization, reducing its leachate toxicity the fastest. Thus, it was concluded that the toxicity tests were effective tool for monitoring the leachate quality after the application of the chemical oxidation method for landfill stabilization and its incorporation to set up the criteria for early- stabilization of landfills needs to be considered.

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[in Japanese]

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[in Japanese]

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Heavy metals such as cadmium were removed from midgut waste of scallops by means of leaching with dilute sulfuric acid solution. After removing large amount of organic materials such as proteins were removed from the leach liquor by means of coagulation with astringent persimmon juice as floc, heavy metals were quantitatively removed by passing the leach liquor through the column packed with apple juice residue gel.

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[in Japanese]

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Organotin compounds(TBT,TPT) assumed for the suspected endocrine disrupting chemicals.They have been detected from seawater and sediment still in high concentration. Moreover, it is a problem that the detoxifying treatment doesn't exist.Then,we are aiming at making of the polluted seawater and sediment quality harmless by using amorphous magnetite that the removal is effective in the heavy metal etc.When amorphous magnetite was added to the polluted seawater, showing the removal by physical adsorption against TBT and the removal by irreversible chemical reaction against TPT in 20degC reactive temperature.Moreover, when a reactive temperature was heated to 60degC, it came to show TBT irreversible chemical reaction.In a word,amorphous magnetite is different from other absorbents, it was a valuable reagent that is able to decompose organotin compounds by irreversible chemical reaction.However, because the contact efficiency is low, the elimination of organotin compounds is poor in sediment.The treatment of sediment will be examined in the future.

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[in Japanese]

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A sulfate pitch has been treated by neutralization-incineration, where neutralization product (calcium sulfate) is generated. The advantage was proven in experiments of laboratory and actual incinerator. Furthermore, characteristics of thermal decomposition of calcium sulfate in organic substance were verified and it was confirmed that reductive decomposition accelerated the thermal decomposition. Successively, experiments of decomposition of calcium sulfate in inorganic salts were recently carried out by quartz-tube combustion method to investigate a variation of thermal decomposition.And it is confirmed that eutectic of calcium sulfate and calcium oxide accelerated thermal decomposition, which means that excess neutralization agent, lime, causes acceleration of thermal decomposition of calcium sulfate. Then it is required to control the amount of lime adequately so as to reduce thermal decomposition of calcium sulfate in the subsequent operation.

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[in Japanese]

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In this study, potassium iodide (KI) was found capable of reducing selenium(VI) to selenium(IV). When KI was added to Se(VI) solution, the Se(VI) concentration dropped rapidly, as the KI/Se(VI) molar ratio increased. Using the potential-pH equilibrium diagram for the selenium/water system, we confirmed that the Se(VI) was reduced to Se(IV) because the potential of the solution shifted to the stable Se(IV) region on the addition of KI. This reduction accompanies the oxidation of I– to I3–. The reduction of Se(VI) by KI was found to be effective for concentrated Se(VI) solutions.

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[in Japanese]

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[in Japanese]

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Environmental risk reduction methods for illegal dumping sites of industrial wastes are described. When storing the industrial wastes in the illegal dumping sites for a relatively long period, diffusion of hazardous materials from the wastes should be prevented in a various ways. The outline of techniques for preventing the diffusion is reported such as sheet capping, wall barrier, leachate treatment, bioremediation and flushing.

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Recently, a problem on large-sized illegal dumping sites has been serious. The dumped waste has been often removed and treated thermally. But because of limitation of capacity of treatment facilities and cost, dumped wastes removal planning considering pretreatment is important to remedy the illegal dumping sites. In this study, a waste removal simulation model was developed considering pretreatment of hazardous wastes to reduce risk. In special, simulation of waste removal was conducted to predict amounts of hazardous and non hazardous wastes to be treated a day, and period for removal of all dumped wastes. As a result, pretreatment of hazardous wastes decreased the amount of hazardous wastes to be treated, and it contributed stable operation of waste removal, which decreased period required for remediation of site.

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Recently, soil and groundwater contamination has been becoming a serious social problem in illegal dumping sites and improper final disposal sites. In addition, a large-sized illegal dumping sites are newly found one after another. The cost effective methods for remediation of such contaminated sites are necessary. In this study, to apply in-situ bioremediation has been investigated as a pretreatment (detoxification) method in order to reduction treatment cost of removed wastes. As the first step, in this study, we carried out a feasibility study on anaerobic bioremediation.To develop numerical model for anaerobic bioremediation, biodegradation term was introduced to the general convection-dispersion equation. To obtain detradation rate constant, vial tests were conducted, whence dechlorination process of PCE was observed. In addition, column tests provided dispersivity, porosity and retardation factor of PCE. Next, the developed numerical model was applied to hypothetical field to predict effectiveness of anaerobic bioremediation. As a result, distribution and time course of concentration of PCE and its by-products were estimated.

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Nowadays, problem on soil and groundwater pollution caused by waste materials has been serious. It is very important to conduct pretreatment to reduce contaminant level for safety work of removal and cost effective treatment of waste. Bioremediation technology is one of the methods. However, bioremediation technology has not been applied to contaminants within waste layers. Therefore, in this study, applicability of bioremediation technology to illegal dumping sites was examined by a biodegradation experiment for benzene in waste like burk compost. At first, benzene was added into the vial including the waste sample obtained from the site. Concentration of benzene in a headspace was measured periodically. As a result, in the both cases of saturated and unsaturated zones, benzene was almost degraded for about one month. In other words, as long as waste layers are controlled under aerobic condition, benzene is degraded by indigenous aerobic bacteria. In addition, toluene and xylene which are analogous compounds as benzene, were degraded under the same conditions.

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[in Japanese]

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[in Japanese]

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