A Study on the water purification mechanism in the mill tailings pond in Ningyo-toge Environmental Engineering Center

Masunaga, Kosuke; Tokoro, Chiharu*; Ohara, Yoshiyuki

In Ningyo-toge Environmental Engineering Center, water level of mill tailings pond is planned to be lowered to reduce overflow risks caused by heavy rain etc., as a part of remediation activities of the Uranium Mine. It is known that the concentration of Fe and As and other elements in the mine drainage are decreased by retaining in the pond. The aims of this study are to reduce the load of water treatment facility and to determine the efficient countermeasure method for remediation of the mill tailings pond. To accomplish these, purification mechanisms of Fe and As in the pond were investigated, referring other studies. Chemical composition of water drainage in the pond was estimated by the chemical equilibrium analysis with advection using PHREEQC. The result of the simulation was almost reproducible for Fe. For As, it was reproducible when taking into account of surface complexation to ferrihydrite in sediment in the bottom of the pond.