Biofilms That Prevent Corrosion

摘要

Corrosion control using regenerative biofilms (CCURB) was shown to occur on mild steel, 304 stainless steel, cartridge brass, red brass and an aluminum alloy in laboratory environments. Mechanisms of protection by CCURB were hypothesized and discussed. For instance, aerobic bacteria in the protective biofilm may consume oxygen dissolved in the water, thereby preventing it from reaching the metal surface and taking part in the corrosion reaction. Bacteria may also secrete corrosion inhibiting compounds that modify the local environment within the biofilm. Also, beneficial bacteria may secrete antimicrobial compounds that kill otherwise harmful sulfate reducing bacteria. Evidence for these mechanisms is presented but no single mechanism explains all observations. Preliminary tests on mild steel in the service water taken from Amergen's Three Mile Island Nuclear Station show that CCURB is possible in real plant environments―not just in carefully controlled laboratory environments.