Use of Clay Minerals to Control Radioactive Cesium Leaching from Municipal Solid Waste Incineration Ash in Fukushima Prefecture in Summer and Winter

Radioactive cesium (r-Cs) released from the 2011 Fukushima Daiichi Nuclear Power Plant attaches to vegetation/soil and is collected as municipal solid waste (MSW) for incineration, being concentrated in incineration ash (bottom ash [BA], fly ash [FA], and chelate-treated FA [TFA]). r-Cs in FA and TFA can easily leach upon contact with moisture. It is important to prevent further contamination, as r-Cs has negative effects on ecosystems and the human body. Naturally available clay minerals, considered effective for capturing r-Cs, are a good alternative. Here, we sampled ash from MSW incineration facilities in Fukushima in August 2016 and February 2017. We used energy dispersive X-ray fluorescence spectroscopy and Ge semiconductor detector to determine elemental composition and r-Cs concentration in the samples and conducted leaching tests. We also determined the extent of leaching suppression by zeolite, acidic clay, and vermiculite. Chloride contents and r-Cs leaching rates were higher in FA and TFA than in BA, regardless of the season. Prior direct addition and mixing of clay minerals (5 to 20 wt.%) effectively prevented r-Cs leaching. This study is the first to examine r-Cs leaching inhibition by clay mineral direct addition and mixing to MSW incineration ash

Use of Clay Minerals to Control Radioactive Cesium Leaching from Municipal Solid Waste Incineration Ash in Fukushima Prefecture in Summer and Winter

Radioactive cesium (r-Cs) released from the 2011 Fukushima Daiichi Nuclear Power Plant attaches to vegetation/soil and is collected as municipal solid waste (MSW) for incineration, being concentrated in incineration ash (bottom ash [BA], fly ash [FA], and chelate-treated FA [TFA]). r-Cs in FA and TFA can easily leach upon contact with moisture. It is important to prevent further contamination, as r-Cs has negative effects on ecosystems and the human body. Naturally available clay minerals, considered effective for capturing r-Cs, are a good alternative. Here, we sampled ash from MSW incineration facilities in Fukushima in August 2016 and February 2017. We used energy dispersive X-ray fluorescence spectroscopy and Ge semiconductor detector to determine elemental composition and r-Cs concentration in the samples and conducted leaching tests. We also determined the extent of leaching suppression by zeolite, acidic clay, and vermiculite. Chloride contents and r-Cs leaching rates were higher in FA and TFA than in BA, regardless of the season. Prior direct addition and mixing of clay minerals (5 to 20 wt.%) effectively prevented r-Cs leaching. This study is the first to examine r-Cs leaching inhibition by clay mineral direct addition and mixing to MSW incineration ash

Enhancement of dissolution rates of amorphous silica by interaction with amino acids in solution at pH 4

Amino acids are present in various geochemical environments and they interact with mineral surfaces. To evaluate the effects of amino acids on mineral dissolution at pH conditions less than their isoelectric points (pI), dissolution experiments of X-ray amorphous silica in solutions containing 10.0 mmol/L of various amino acids (cysteine, asparagine, serine, tryptophan, alanine, threonine, histidine, lysine, and arginine) at pH 4 were performed. The results confirmed that basic amino acids (histidine, lysine, and arginine) produce an 8- to 8.5-fold enhancement of the rate of dissolution of amorphous silica compared with an amino acid-free control. Neutral amino acids (cysteine, asparagine, serine, tryptophan, alanine, and threonine) enhanced rates of dissolution by a factor of ~3 to 3.5. The rate- enhancement effects of amino acids are controlled by concentrations of the amino acid's cationic species which interact with the negatively charged >SiO sites at the surface of the amorphous silica

Laboratory experiments on bacterial weathering of granite and its constituent minerals

This study focuses on weathering of granitic minerals by the bacteria Bacillus subtilis, specially how the ubiquitous soil bacterium Bacillus subtilis weathers granitic minerals through image analysis of mineral surface, and which mineral in the granite is the most vulnerable to weathering in a bacterial circumstance through comparison of using rock and single minerals analysis. Laboratory experiments reveal three basic conclusions: (i) Bacteria enhance weathering of granite and its constituent minerals by making pits on the mineral surface; (ii) The plagioclase is the most vulnerable mineral in bacteria-bearing granite. In the mineral experiments, albite (plagioclase group) is the most vulnerable in bacterial experiment; (iii) The orders of normalised pit-area ratio and pit density in bacteria-bearing granite are in accorded with the traditional weathering-series; this accordance suggests that bacterial weathering may have a large effect as biochemical weathering process.Cette étude s’intéresse à la météorisation bactérienne du granite et de ses minéraux par Bacillus subtilis. Une expérimentation en laboratoire pendant 30 jours a permis de répondre aux interrogations suivantes : de quelles manières la bactérie ubiquiste Bacillus subtilis altère-t-elle le granite et ses minéraux (analyse d’images exoscopiques) ? Quels minéraux du granite sont les plus vulnérables dans un environnement bactérien (modèle rocheux et mono-minéral) ? Les résultats obtenus à la suite de plusieurs protocoles expérimentaux sont : 1) les bactéries augmentent la météorisation du granite et de ses minéraux par formation de puits à la surface des minéraux ; 2) les plagioclases sont les minéraux les plus fragiles lorsque le granite est au contact de bactéries. Dans le protocole mono-minéral, l’albite (groupe des plagioclases) est le plus vulnérable ; 3) le classement normalisé du rapport puit/surface et la densité de puits dans le protocole bactérien est en accord avec l’ordre traditionnel de météorisation des minéraux, indiquant que la météorisation bactérienne contribue largement au processus d’altération