Field Assessment of Biogenic Acid Attack in Concrete Structures

Biogenic sulfuric acid attack (BSA) is a biodegradation mechanism that causes accelerated deterioration of concrete sewer systems and wastewater treatment structures. BSA is a multi-stage biological process that deposits sulfuric acid over concrete surfaces. Due to its complex nature, there are no current standards to evaluate the presence, extent, and severity of BSA in concrete structures during service. The authors evaluated the chemical and biological conditions in an operational digester where BSA activity was suspected. The evaluation included microbial culture testing, quantitative polymerase chain reaction (qPCR) analysis of biofilm samples, pH measurements, and petrographic assessment of extracted samples. To evaluate the effect of oxygen on BSA activity, evaluations were performed in strictly anaerobic and oxygen-rich environments inside the same digester. The investigation determined that oxygen injection caused significant changes in the biological and chemical conditions inside the digester. The addition of oxygen promoted BSA activity and the associated production of sulfuric acid, and therefore accelerated concrete deterioration.

Automated summary

Biogenic sulfuric acid attack (BSA) is a biodegradation mechanism that leads to accelerated deterioration of concrete structures. There are currently no standards to evaluate the presence, extent, and severity of BSA in concrete. By evaluating the chemical and biological conditions in a digester, the study found that oxygen injection promotes BSA activity and accelerates concrete deterioration.