How do I find the biofilm aggressiveness value?
This value is like the rate constant in a chemical reaction. It reflects the ability of the biofilm to catalyze sulfate reduction. You can use a pit depth data point to calibrate it. Fortunately, biofilm aggressiveness is a sensitive parameter for deep (several mm) pit growth because mass transfer is in control. This means cathodic sulfate reduction is limited by the ability of sulfate to diffuse through mass transfer barriers to get to the metal surface, regardless how aggressive an SRB biofilm is. In such a case, you can use a typical value (say -10). Remember, you can always use different biofilm aggressiveness value to test its sensitivity! We have seen published pit data in NACE papers for SRB indicate pit depth of up to 10 microns in the first 24 hours at 37oC. Some reported only 20 microns in 7 days. These lab pit data give biofilm aggressiveness between -9.5 to -12.3 When using MICORP to calibrate such shallow pits, mass transfer parameters are not sensitive at all because char
