Removal of Arsenic from Geothermal Water by using High Intensity Field and High Gradient Magnetic Separation

We have developed a High Gradient Magnetic Separation (HGMS) system to remove arsenic from geothermal water by using a superconducting magnet. We attained the reduction of arsenic concentration less than the effluent standard of 0.1 mg/L and slightly larger than the environmental standard of 0.01 mg/L in Japan. The system consists of a pretreatment process that adds extra magnetization to arsenic by chemical reaction, and a reciprocating HGMS filter using a superconducting magnet that extracts magnetized arsenic from the geothermal water. We improved efficiency of the pretreatment process with reusing the deposition and optimiizing chemical conditions. The reciprocating HGMS filter can reduce the time for rinsing the filter. We present the experimental results of the removal system and an estimate of a practical plant to supply hot water for public use on the basis of them.