The Removal of Arsenic and Silica from Geothermal Fluids by Electrocoagulation

Abstract

Electrocoagulation treatment offers a simpler and more cost-effective method of removing arsenic from separated geothermal water than the traditional treatment methods of coagulation and flocculation. It is an electrochemical process that uses direct current to remove a wide range of contaminants. This method has the potential to allow efficient downstream utilization of heat in low enthalpy fluids through cascaded direct use applications and provides a more cost effective disposal option than reinjection. Laboratory scale experiments showed that the process was capable of rapidly removing both silica and arsenic from aged solutions leaving a floc which readily settled on standing. In a full scale process the silica and arsenic can be removed as two separate components allowing an arsenic free silica sludge to be disposed of to a landfill and thereby leaving a much smaller arsenic/iron fraction to be disposed of by reinjection.