Media Release

Ohio Sanitation Sewer System Beats the MIC Threat with Penetron Antimicrobial Admixture


Construction work at the Orchard Island sanitation sewer system in Bellefontaine, Ohio, was completed by October 2023. The repair and upgrade project helped the Logan County Water Pollution Control District meet the Compliance Schedule issued by the Ohio EPA. Penetron’s antimicrobial concrete admixture provided the crucial permanent concrete protection for the new sanitary sewer lines, lift stations, and a pressure sewer from microbially-induced corrosion, which can rapidly compromise and disable concrete structures.

The Logan County Water Pollution Control District provides service to the residents of the Orchard Island and Wolfe Island areas in central western Ohio.

“By 2020, the repair of the Orchard Island infrastructure became urgent. The District’s sanitary sewers were at the end of their service life and had begun to fail. This allowed significant amounts of clean water to enter the system through joints, cracks sump pump connections, and other sources, bypassing the wastewater treatment plant,” explains Christopher Chen, Director of The Penetron Group. “As a result, the Ohio EPA issued a Compliance Schedule to the District to remove clean water from the sanitary sewer system and prevent any further sanitary sewer overflows.”

However, before construction could begin, the Orchard Island project engineer at Choice One Engineering needed a proven and durable solution to avoid the threat of microbially induced corrosion (MIC) to both the new and repaired concrete structures that were part of the project.

For the construction industry, MIC is a serious challenge that causes billions of dollars in damage to wastewater and sewage-related concrete structures every year. The root cause is the thiobacillus bacteria found in sewage and septic environments, which converts hydrogen sulfide gas (H2S) into biogenic sulfuric acid (H2SO4). The presence of sulfuric acid on concrete surfaces can unleash highly localized and rapid corrosion processes that eat away the cement paste of the concrete matrix. This, in turn, can quickly expose the embedded reinforcement steel of underground concrete sewage systems to water, oxygen, CO2, and chlorides – resulting in catastrophic corrosion-related failures in the concrete.

“Initially, a competitive antimicrobial product was specified for the Orchard Island project. After Choice One Engineering saw how our antimicrobial concrete admixture had performed in many similar projects across the country, Penetron won the job,” says Christopher Chen.

Penetron’s antimicrobial admixture prevents microbial-induced corrosion (MIC) by using an electro-physical mechanism to destroy the cell walls of the thiobacillus bacteria, also known as acid-producing bacteria. Eliminating the bacterial growth on and in concrete consistently stops the formation of biogenic sulfuric acid, avoiding the damage caused by MIC.

Bluffton Precast added Penetron’s antimicrobial admixture to the concrete mix for all precast elements. Identical to the well-known PENETRON ADMIX, a crystalline concrete waterproofing admixture, the antimicrobial properties of the admixture are permanent; it becomes part of the concrete matrix and is leach resistant, even repeated contact with bacteria does not lessen the effectiveness of the admixture.

The ensuing renovation work for Orchard Island replaced all main sewer lines (including residential connections in the rights-of-way), added new pump stations and a pressure sewer connected to the Logan County Water Pollution Control District’s sanitary sewer system.

“Thanks to an effective antimicrobial technology and attractive cost, Penetron’s antimicrobial concrete admixture will provide the long-term protection from MIC that the Orchard Island project required,” adds Christopher Chen. “The enhanced durability will minimize the need for future repairs of the treated concrete structures.”