PRINCIPAL FACTORS AFFECTING MICROBIOLOGICALLY INFLUENCED CORROSION OF CARBON-STEEL

Laboratory-scale batch experiments (semicontinuously fed) were conducted using a two-level factorial experimental design to investigate principal factors and interactions affecting microbiologically influenced corrosion (MIC) of carbon (C) steel. Factors considered included the C source as chemical oxygen demand (COD), sulfate (SO42-) concentration, calcium carbonate (CaCO3) precipitation, and bacteria inoculation at 20 degrees C. Yates' algorithm was applied to calculate main and interaction effects, and an empirical model indicating major trends was obtained. Experimental results showed CaCO3 precipitation played a significant role in influencing the biocorrosion tendency of steel. In the supersaturated condition, SO42- concentration and bacterial inoculation had no appreciable effects on corrosion. In the undersaturated condition, the corrosion rate was affected significantly by SO42- concentration and bacterial inoculation. The effect of each factor on corrosion rate was explored.