Abstract
At Sumikawa geothermal plant in Akita prefecture, the geothermal water after separator is directed back underground through a re-injection well because it contains high level of As (ca. 13mg/l). In order to establish the effective system for the removal of As from geothermal water using H2S gas included in exhausted gas, we examined the basic reaction of As removal from geothermal water by artificial H2S gas. In the case of less than pH 4 of geothermal water, As concentration of the water dropped to below 0.1mg/l after passing through H2S gas. This process can be combined with removal method of supersaturated silica by using Al ion.
