Effects of Ferrous Ions on the Metabolism of Sulfate-reducing Bacteria

Abstract

Effects of ferrous ions on the growth and activity of sulfate-reducing bacteria (SRB) have been investigated using biological and analytical techniques for a better understanding of its metabolism in corrosive media with high contents of metal ions. In-situ gravimetry by the quartz crystal microbalance (QCM) technique was also applied to examine the sulfide-producing process in the medium. The growth of SRB increased with increasing ferrous ion concentration up to 0.01M and retarded above 0.01M. In the low concentration region (0.00036M-0.01M) ferrous ions enhanced the growth of SRB, whereas in the high concetration region (0.03M-0.7M) ferrous ions gave the opposite effect due to high osmotic pressure. The FeS producing ability was closely related to the growth of bacteria, therefore it seems that SRB accelerates the corrosion of metal in the medium including 0.01M ferrous ions. QCM technique was able to detect sensitively the amount of FeS attached on the electrode surface, which was proportional to the total amount of FeS in the medium. Thus it was found that QCM technique is powerful for monitoring the FeS producing process.