Multi-technique approach to assess the effects of microbial biofilms involved in copper plumbing corrosion

Microbially influenced corrosion (MIC) is recognized as an unusual and severe type of corrosion that causes costly failures around the world. A microbial biofilm could enhance the copper release from copper plumbing into the water by forming a reactive interface. The biofilm increases the corrosion rate, the mobility of labile copper from its matrix and the detachment of particles enriched with copper under variable shear stress due to flow conditions. MIC is currently considered as a series of interdependent processes occurring at the metal-liquid interface. The presence of a biofilm results in the following effects: (a) the formation of localized microenvironments with distinct pH, dissolved oxygen concentrations, and redox conditions; (b) sorption and desorption of labile copper bonded to organic compounds under changing water chemistry conditions; (c) change in morphology by deposition of solid corrosion by-products; (d) diffusive transport of reactive chemical species from or towards the metal surface; and (e) detachment of scale particles under flow conditions. Using a multi-technique approach that combines pipe and coupon experiments this paper reviews the effects of microbial biofilms on the corrosion of copper plumbing systems, and proposes an integrated conceptual model for this phenomenon supported by new experimental data.