Precasters take biology lessons to increase the life of concrete sewer systems.
About 40% of the more than 20,000 wastewater systems in the United States are concrete. Corrosion severely compromises the structural integrity of these concrete components, costing millions in repairs.
Six decades after C.D. Parker discovered Microbial Induced Corrosion (MIC), many continue to incorrectly refer to the deterioration of sewer pipe as “a corrosive gas problem.” But the real culprit for concrete is MIC, a process by which sulfuric acid is produced in sewer systems when hydrogen sulfide gas and Thiobacillus bacteria interact.
Anaerobic (non-air breathing) bacteria form in raw sewage and naturally produce hydrogen sulfide gas (H2S) in sewer effluent. Factors contributing to rapid bacterial growth are temperature, retention time, high biological oxygen demand levels, and turbulence.
The more turbulent the effluent, the more hydrogen sulfide is released.