Abstract
At geothermal plant, the geothermal water after separation contains high level of As over Japanese effluent standard level and much silica to cause silica scale. In order to establish the effective utilization system for geothermal resources, we tried to remove As and silica from geothermal water, simultaneously, using inorganic anion exchanger, hydrotalcite. The treatment of geothermal water with hydrotalcite could remove As and silica, simultaneously, and As and silica concentrations dropped to below Japanese effluent standard level (0.1mg/l) and the level to prevent silica scale (100mg/l), respectively, in the range of temperature between 25°C and 80°C. Calcined hydrotalcite indicated more effective removals of As and silica than non-calcined hydrotalcite. The residue after the treatment mostly retained As and silica, which was removed from geothermal water, by heating at 60°C.
