Bacteriological challenges to asbestos cement water distribution pipelines

Area of Science:

• Microbiology
• Environmental Science
• Materials Science

Background:

• Asbestos cement (AC) pipes were widely used in drinking water systems from the 1920s to the 1980s.
• Increased water main breaks in AC pipes are linked to aging and corrosion.
• The role of microorganisms in AC pipe degradation requires further investigation.

Purpose of the Study:

• To evaluate the potential role of microorganisms in the degeneration and failure of AC pipes.
• To identify microbial populations associated with AC pipe surfaces.
• To assess the impact of specific bacteria on AC pipe integrity.

Main Methods:

• Collected AC pipe samples from a drinking water distribution network.
• Examined pipe surfaces for microbial growth and patina formation.
• Utilized BART testers to identify microbial populations.
• Conducted microbial challenge assays under aerobic and anaerobic conditions.

Main Results:

• Observed black slime bacterial growths and iron oxide-rich patina on inner pipe surfaces.
• Identified dominant microbial groups including Heterotrophic Aerobic Bacteria (HAB) and Slime Forming Bacteria (SLYM).
• Found that acid-producing bacteria, SLYM, and HAB accelerated pipe weight loss under anaerobic conditions.

Conclusions:

• Microbial activity significantly contributes to AC pipe deterioration.
• Specific bacterial groups play a key role in the corrosion and failure of AC pipes.
• Understanding microbial impacts is crucial for managing aging water distribution infrastructure.