| Abstract |
Geothermal solid wastes such as scale and sludge from the Philippines and Mexico containing Cu, Zn,and Pb at levels above earth's crustal abundance were studied for their acidification potential if disposed in a landfill. A batch reactor technique using the iron and sulfur oxidizing bacteria Thiobacillus ferrooxidans was developed for geothermal wastes to predict their acid mine drainage and bioleaching potential. It was observed that almost 100% of Cu and Zn in the Mexican scale and less than 2% in the Philippine scale and sludge were released while Pb, the regulated element, was not found in the leachate which probably precipitated as PbSO. This indicates that these geothermal residues likely will not be a threat to the environment due to their silicate nature and can safely be disposed in a landfill. |