Latest Decon Technology from Japan: Coffee Filter

This one may actually work, if they can do it on a large scale. But I just can't visualize how.

A university researcher and his friend have come up with a cesium removal system from fallen leaves using a coffee filter.

From Mainichi Shinbun (12/15/2011):

落ち葉のセシウム　完全除去法を開発

A system to completely remove radioactive cesium from fallen leaves developed

　落ち葉や雑草などから放射性セシウムを完全に除去する方法を、千葉大工学部の片山栄作特別研究員（６２）＝元東大医科学研究所教授＝と群馬県渋川市の阿藤工務店専務、川上勇さん（６３）が開発した。セシウムが葉や茎に含まれる「プラントオパール」（植物石）と呼ばれる粒子に結合していることを突き止め、プラントオパールを分離することでセシウム除去に成功。片山さんは「さまざまな除染に応用できる」と期待している。

Eisaku Katayama, 62-year-old researcher at the Engineering Department of Chiba University and former Professor of Tokyo University Medical Research Institute, and Isamu Kawakami, 63-year-old executive at a building firm in Shibukawa City in Gunma Prefecture have come up with a system to completely remove radioactive cesium from fallen leaves and weeds. They discovered that cesium binds to "plant opals" in leaves and stems of plants, and succeeded in removing cesium by removing the plant opals. Katayama is hopeful that their system "can be used in a variety of decontamination work".

　２人は放射性セシウムに、雲母などケイ酸化合物を主成分とする鉱物と強く結合する性質があることに着目。同じ主成分のプラントオパールにも同様の現象が起きるとの仮説を立てて実験した。

The two focused on the characteristics of radioactive cesium which strongly binds with minerals whose main ingredient is silicon compound such as mica. Since plant opals contain the silicon compound, they hypothesized that the similar phenomenon may happen with the plant opals and conducted the experiment.

　福島県南相馬市で１１月中旬、刈り取られた雑草５７０グラムを水分が蒸発しないよう密封。どろどろの液状に腐らせた後の１２月１０日に測定すると、１キロあたり２万８９２４ベクレルの放射性セシウムが計測された。これに水を加えてコーヒーフィルターでろ過すると、ろ過後の液体からは検出されなかった。フィルターに残ったかすを顕微鏡で観察すると、多数のプラントオパールを確認。セシウムがプラントオパールと化学的に結合し、フィルターに引っかかったとみられる。

First, they put 570 grams of weeds from Minami Soma City, Fukushima Prefecture in a sealed container in mid November. After letting it rot until liquefied, they measured the density of radioactive cesium on December 10. The result was 28,924 becquerels/kg. They added water to this weed sludge, and filtered it using a coffee filter. They found that radioactive cesium was not detected from the filtered water. Upon close inspection of what remained on the coffee filter using a microscope, they identified numerous plant opals. They concluded that radioactive cesium had chemically bound with plant opals, and didn't go through the filter.

　かすの容積は元の雑草の約１０分の１になった。かすにはセシウムが濃縮されるが、置き場探しが課題の落ち葉や雑草の容積を減らせるとみて、２人は大量に処理できる装置を開発したい考えだ。

The dreg left on the filter was about one-tenths of the weeds. It contains concentrated level of radioactive cesium, but they want to develop a system to process a large amount of fallen leaves and weeds, as the system may be able to reduce the bulk of the leaves and weeds that takes up storage space.

　プラントオパールは数マイクロメートル～１００マイクロメートルほどの粒子。枯れた葉からはがれて飛散することから、片山さんらは▽落ち葉や雑草は野積みせず閉鎖された所に保管する▽植物の多い汚染地域ではマスクをする－－などの対策が必要と指摘している。

A plant opal is a particle between several and 100 micrometer in diameter. It gets detached from fallen leaves and scatter. Katayama points out that it is necessary to store fallen leaves and weeds in an enclosed area and not in the open, and to wear masks in the contaminated areas with many plants.

　片山さんと川上さんは趣味の天文観測仲間。福島県の友人から除染の相談を受けた川上さんが研究を進め、片山さんが協力した。片山さんは「本来なら論文にして発表するところですが、被災地のために実用化を優先します」と話している。

Katayama and Kawakami became friends through their common hobby, astronomical observation. After being consulted by his friend in Fukushima Prefecture on decontamination, Kawakami did the research, with the help of Katayama. Katayama says, "It should have been written up and published as a research paper, but for the sake of the disaster-affected areas we'll put developing the practical application first."

If only radioactive cesium were the only nuclide that fell.

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