Evaluating the efficacy of antimicrobial additives against biogenic acidification in simulated wastewater exposure solutions

Microbially Induced Corrosion of Concrete (MICC) is a progressive three-stage deterioration process that is primarily associated with sulfur-oxidizing bacteria (SOB). One strategy for mitigating MICC is the use of antimicrobial additives. It is hypothesized that the performance of antimicrobial products is influenced by the pH of the environment, the bacterial population, and the level of bacterial activity. To test this hypothesis, three bacterial activity-population levels were tested in environments with different pH levels to evaluate the efficacy of a typical antimicrobial product against planktonic SOB. The ability of the antimicrobial product to prevent or delay the biogenic acidification was considered as the criterion for its efficacy. The tested antimicrobial product was successful in delaying or preventing MICC with low and moderate bacterial populations and activity for all pH levels greater than 4. Lower pH levels were not tested in this investigation.  Antimicrobial products were successful in delaying or preventing MICC with severe bacterial populations and activity for all pH levels tested greater than 6. The results support the main hypothesis of the research; therefore, the selection of whether to utilize an antimicrobial product requires an understanding of the operational pH of the environment as well as knowledge on the target bacterial population and activity.