Removal of Arsenic from Geothermal Water

Abstract

The coprecipitation techniques using respectively iron(111) hydroxide and salt followed by hydrolysis was employed to remove the arsenic from geothermal water in the Ohtake area, Kyushu, Japan. For both methods, the optimum were found to be about 3. The Fe requirements to lower the residual arsenic concentration to environmental standard(0.05 ppm) were at least 45 method), and 25 method). In case of the method, the time did not influence the arsenic removal. While for the method, the effect of arsenic removal was influenced by stirring time. Effect of treatment temperature was also examined. In the range of 3 was the optimum and at temperature, 5 was the optimum on arsenic removal. Silicic acid in geothermal water is said to interfere the arsenic removal, but present study showed that it was true in acidic state, but in the alkaline state, the existence of the colloidal silica on hydroxide prevented the desorption and/or elution of arsenic.