Detail study on effective removal of Cesium from ash samples generated from wood bark, household garbage and municipal sewage sludge was performed. For wood ash and garbage ash, washing only with water at ambient conditions removed radioactivity due to 134Cs and 137Cs, retaining most of the components other than the alkali metals with the residue. However, removing Cesium from sludge ash needed acid treatment at high temperature. This difference in Cesium solubility is due to the presence of soil particle originated clay minerals in the sludge ash. Because only removing the contaminated vegetation is found to sharply decrease the environmental radioactivity, volume reduction of contaminated biomass by incineration makes great sense.
In addition, long term need of leachate monitoring system in the landfill can be avoided by washing the ash with water. Once the Cesium in solids is extracted to the solution, it can be loaded to Cesium selective adsorbents like Prussian blue and safely stored in a small volume.
Abstract of the paper by Durga Parajuli , Hisashi Tanaka , Yukiya Hakuta , Kimitaka Minami , Tohru Kawamoto , and Shigeharu Fukuda
March 13, 2013