Yasushi Matsufuji

Influence of soil properties on the biodegradation of 1,3,6,8-tetrachlorodibenzo-p-dioxin and fungal treatment of contaminated paddy soil by white rot fungus Phlebia brevispora.

To examine the bioremediation potential of Phlebia brevispora in dioxin-contaminated soil, the fungus was inoculated into autoclaved soil that was contaminated with 2,7-dichlorodibenzo-p-dioxin (2,7-DCDD) or 1,3,6,8-tetrachlorodibenzo-p-dioxin (1,3,6,8-TCDD). Three types of soils, organic-rich soil (Andosol), organic-poor soil (Granitic Regosols), and paddy soil, were used for the construction of artificially contaminated soil to understand the influence of the soil property on fungal growth and dioxin degradation ability. Under a solid-state condition, although the growth of the fungus improved in organic-rich soil, the degradation of 2,7-DCDD was inhibited. Although the degradation of 1,3,6,8-TCDD under a solid-state condition was inhibited severely, 1,3,6,8-TCDD degradation was observed under a slurry-state condition in organic-poor soil. In the case of organic-rich soil, an increase in water content improved the 1,3,6,8-TCDD degradation efficiency. When the historically contaminated paddy soil was treated with P. brevispora under a slurry-state condition, 1,3,6,8-TCDD as the main contaminant degraded 50% after 90d incubation.

Generation of greenhouse effect gases from different landfill types

Abstract Recently much attention is focussed on the problems of global warming due to greenhouse effect gases, notably carbon dioxide and methane. Because these gases cause important problems to the global environment, their generation from landfill sites containing solid wastes has drawn attention and their environmental impact is causing concern. Generally, the gases associated with a greenhouse effect include carbon dioxide, methane and nitrous oxide. However, there are no general basic data available concerning gases generated from biodegradation of solid wastes in landfill sites. Specifically, no assessment has been made concerning greenhouse effect gases from different landfill types. This paper proposes a quantitative model for estimating the gasification rate by different landfill types. The model is based on measurement data for a long-term material balance for an aerobic landfill and an anaerobic landfill, obtained with two types of large-scale lysimeters. This paper will also give an estimate for the amount of greenhouse effect gases by for different types of landfill and propose countermeasures for their reduction.

Leaching of brominated flame retardants from mixed wastes in lysimeters under conditions simulating landfills in developing countries.

In developing countries, wastes are usually not separated before being disposed of in solid-waste landfills, most of which are open dumps without adequate measures to prevent environmental pollution. To understand the leaching behavior of brominated flame retardants (BFRs) from waste consumer products in landfills, we have been conducting a long-term landfill lysimeter experiment since 2006 under conditions designed to mimic three types of landfill conditions in developing countries: aerobic, semi-aerobic, and anaerobic. Pilot-scale lysimeters (60-cm i.d.) were filled with a 400-cm layer of mixed wastes consisting of 35 wt% food, 20 wt% paper, 20 wt% paper pulp, 13 wt% plastic, 10 wt% wood chips, 1 wt% glass, and 1 wt% metals, proportions that are typical of unsorted municipal solid waste in Asian developing countries. In the present study, we determined the concentrations of polybrominated diphenyl ethers, tetrabromobisphenol A, tribromophenols, and hexabromocyclododecanes in leachate samples collected from the lysimeters during the first 3.5 years of the experiment, to evaluate BFR elution behavior in early-stage landfills. Under all three conditions, BFR elution started at the beginning of the experiment. The BFR concentrations in the leachates from the aerobic lysimeter tended to be lower than those from the anaerobic lysimeter, suggesting that the presence of air inside landfills considerably reduces BFR elution to the surrounding environment. During the 3.5-year experiment, BFR outflow from the lysimeters was only 0.001-0.58% of the total BFRs in the loaded waste; that is, most of the BFRs in the waste remained in the lysimeters.

Pollutant transformations in landfill layers

Abstract The behaviour of pollutants, in particular organic carbon and nitrogen, in solid waste landfill layers and factors affecting their decomposition have been studied using four large scale simulated lysimeters in four landfill thicknesses, and operated under semi-aerobic conditions. This paper presents about 800 days of data through November 1991. Data in this study indicate that the thicker solid waste layer has lower production rates of Total Organic Carbon (TOC) and Total Nitrogen (T-N) than does the thinner layer. If the layer, however, becomes too thick, no significant increase in the removal rate of T-N is observed, as nitrogen is leached out in the form of NO 3 − -N without being demitrified at the bottom of the landfill layer. It is also assumed that temperature and pH in the landfill layer play important roles not only in microbial degradation, but also in dissolution of organic carbon and nitrogen.

Modeling the fate and end-of-life phase of engineered nanomaterials in the Japanese construction sector

To date construction materials that contain engineered nanomaterials (ENMs) are available at the markets, but at the same time very little is known about their environmental fate. Therefore, this study aimed at modeling the potential fate of ENMs by using the example of the Japanese construction sector and by conducting a dynamic material flow analysis. Expert interviews and national reports revealed that about 3920-4660 tons of ENMs are annually used for construction materials in Japan. Nanoscale TiO2, SiO2, Al2O3 and carbon black have already been applied for decades to wall paints, road markings or concrete. The dynamic material flow model indicates that in 2016 about 95% of ENMs, which have been used since their year of market penetration, remained in buildings, whereas only 5% ended up in the Japanese waste management system or were diffusely released into the environment. Considering the current Japanese waste management system, ENMs were predicted to end up in recycled materials (40-47%) or in landfills (36-41%). It was estimated that only a small proportion was used in agriculture (5-7%, as ENM-containing sewage sludges) or was diffusely released into soils, surface waters or the atmosphere (5-19%). The results indicate that ENM release predominantly depend on their specific applications and characteristics. The model also highlights the importance of adequate collection and treatment of ENM-containing wastes. In future, similar dynamic flow models for other countries should consider, inasmuch as available, historical data on ENM production (e.g. like declaration reports that are annually published by relevant public authorities or associations), as such input data is very important regarding data reliability in order to decrease uncertainties and to continuously improve model accuracy. In addition, more environmental monitoring studies that aim at the quantification of ENM release and inadvertent transfer, particularly triggered by waste treatment processes, would be needed in order to validate such models.

Production Process of Mutagens in Landfill Site received Incineration Residue

筆者らは有害化学物質による埋立地のリスクを軽減することを目的として, バイオアッセイ, 特に変異原性試験による有害性の評価に注目し, 埋立廃棄物および浸出水の変異原性の調査を行っている。これまでに, 埋立地浸出水を用いて最適な変異原物質の濃縮・変異原性試験の方法について検討した。また, 実埋立地浸出水の調査を通して, 浸出水の生物的酸化処理によって変異原物質が生成されることを明らかにした。そこで本研究では, 埋立模型槽を用いて廃棄物の種類および埋立条件と変異原性の関係を調査し, 浸出水中に主に検出されるフレームシフト型の直接変異原物質の生成機構とその要因について検討した。さらに, この結果を基に, 変異原物質の生成実験を行い, 生成機構の検証を行った。その結果, (1) 好気的な埋立構造ほど変異原性の出現が早いこと, (2) 焼却灰と窒素化合物を含む廃棄物を埋め立てた場合, 生物的硝化過程および硝酸塩の化学的還元過程におけるNO-2およびN2Oの生成初期に変異原物質が生成されること, (3) 硝酸塩の還元過程において検出される変異原物質に多環芳香族炭化水素のニトロ誘導体や芳香族アミンが含まれていること等が明らかになった。

Biological Treatability Studies of tetrachloroethylene-Contaminated Soil

土壌中のテトラクロロエチレン (PCE) の嫌気的脱塩素化処理を目的として, 汚染土壌を詰めたカラムを用いて実験した。脱塩素化菌群の集積培養液を植種源として, また豆腐製造廃液を電子供与体として用い, 29ヵ月間, 汚染土壌を浸漬したところ, 土壌中のPCEの約35%および間隙水中の88%以上がジクロロエチレン (DCE) まで脱塩素された。しかし, エチレンまでの完全脱塩素化は進行しなかった。一方, 汚染土壌の上部に電子供与体となるウッドチップを詰めて, 下部から溶出液を採取する半連続カラム実験を行ったところ, 25日後の溶出液中には, DCEだけが検出された。それとともに, DCEの溶出量が増加し, 計算では, 汚染土壌中のPCEの完全溶出年数は11.7年から4.5年に減少した。このカラム実験でも, 完全脱塩素化は困難であったことから, カラム溶出液中のDCEの好気的分解を検討した。その結果, トルエンまたはフェノールを添加した場合にDCEの分解が認められた。また, 遺伝子組換え菌の静止菌体の利用が特に有効であった。