Fundamental Study of Adsorption Thin Layers for Safe Storage of Heavy Metal Contaminated Soil

In Japan, arsenic is contained in excavated muck. Arsenic is both highly toxic and soluble, and the Japanese government has set environmental standards to prevent arsenic from penetrating groundwater. Industries are obliged to take countermeasures to prevent the permeation of excavated muck containing arsenic into groundwater. Arsenic levels should not exceed values established in environmental standards, regardless of whether the pollution is from human or natural sources. Currently, countermeasures such as the use of adsorption layers are applied to prevent heavy metals from penetrating groundwater. The adsorption layer method involves mixing chemical reagents that adsorb heavy metals, with non-contaminated soil on site to build an adsorption layer. The contaminated soil is then embanked on the adsorption layer. If leachate containing arsenic is generated, it adheres to the adsorption layer when it flows out of the soil, preventing it from penetrating groundwater. The arsenic adsorption effect is diminished if the on-site mixing of chemicals and non-contaminated soil is incomplete. Therefore, to ensure optimal performance of the adsorption layer, the use of high-quality “pre-made adsorbent layers” is considered. It is difficult to construct pre-made adsorbent layers in a manner that corresponds to the landform. Newly developed pre-made adsorbing layers can be adapted to the shape of the landform, which reduces the material disposal rate and subsequent environmental impact. The adsorption thin layer was manufactured and exposed to hot air welding tests and construction tests. It can be easily arranged, both on flat surfaces and slopes.