| Abstract: | The effects of goethite on the anaerobic bio-decomposition of sulfate minerals were investigated by using the beef extract
as a carbon source and the activated sludge as the source of mixed bacteria. Solution pH, sulfate concentration, total iron
ion concentration and the solid products of four different batch tests were monitored and analyzed. Experimental results showed
that the presence of iron oxide can improve the alkalinity of the reaction system which results in the increase of pH value.
Moreover, the added goethite consumed a large amount of H2S generated from the sulfate minerals by SRB, thereby significantly enhancing the decomposition of gypsum and anhydrite compared
with the control batch tests. In addition, the SEM observation and the EDS spectra showed that there were some rod-shaped
microorganisms and new generated minerals, such as iron sulfide, calcium carbonate crystals, and elemental sulfur. Both of
the proliferation of new minerals (iron sulfide and calcium carbonate crystals) and the complete disappearance of sulfate
minerals indicated that iron oxide can play the role in fixing the S element through the metabolism of SRB and hence improve
the bio-decomposition of sulfate minerals. |
