Corrosion Control Using Regenerative Biofilms (CCURB): An update

Corrosion Control Using Regenerative Biofilms (Corrosion CURB or, simply, CCURB), a phenomenon that has only recently been studied to any significant degree, involves the formation of protective surface films by bacteria. One advantage of these biofilms is that they repair themselves when damaged. Aerobic bacteria have been studied that can form protective biofilms on the iron, copper, and aluminum alloys used in power plants, giving rise to quite significant decreases in corrosion rate. One reason for the reduced corrosion rates is that the aerobic bacteria in the surface of the biofilm consume oxygen in the water before it can reach the metal surface and participate in the corrosion reaction. In addition, the beneficial aerobic bacteria can be genetically engineered to produce and release corrosion-inhibiting compounds or antimicrobial compounds. The latter kills potentially deleterious anaerobic bacteria, such as sulfate reducing bacteria (SRB). Concurrent field testing is underway in several power pl ant service water systems. Biofilm samples from these plants are being examined to determine the nature and abundance of naturally occurring bacteria. One or more of these bacteria will be chosen as "hosts" that will be engineered to provide corrosion protection to metals and alloys, first in an adjacent instrumented closed-loop sidestream, but eventually in the service water system itself.