IS METABOLIC-ACTIVITY BY BIOFILMS WITH SULFATE-REDUCING BACTERIAL CONSORTIA ESSENTIAL FOR LONG-TERM PROPAGATION OF PITTING CORROSION OF STAINLESS-STEEL

Concentric electrodes have been fabricated from 304 stainless steel in which a small anode (0.031 cm(2)) and large cathode (4.87 cm(2)) are induced by the application of a current density of 11 mu A cm(-2) at the anode. It has previously been shown that reproducible pitting and maintenance of a galvanic current occurs only in the presence of a censortium of bacteria containing sulphate-reducing bacteria (SRB). Actively corroding systems that had maintained a galvanic current for at least 24 h after the applied current was removed were treated with inhibitors of the SRB. The only inhibitor tested which had any marked effect on the galvanic current was sodium molybdate which is a known inhibitor of corrosion as well as SRB.