Erosion and sloughing off of biofilms causes the detachment of biomass from surfaces, and their transport to sedimentation and entrapment points within the distribution system. This results in the blockage of filter traps, pumps, dead-legs, valves, etc. In addition, customer complaints may increase due to blockage of service lines, water meters and faucet screens.
This is caused by sessile anaerobic bacteria such as sulfate reducing bacteria, growing under a biofilm. This results into a greatly reduced pH at the metal surface causing localized corrosion, similar to pitting. Pitting is understood to be a more damaging form of corrosion when compared to general corrosion, within a distribution system.
Adsorption of Corrosion Inhibitors
Biofilms prevent inhibitors, such as blended phosphates based products, from adsorbing onto the system metal surfaces. This in turn blocks the corrosion inhibitor’s ability to provide protection. In addition to this, the biofilms may cause a higher chlorine or disinfectant feedrate increasing the overall system corrosivity.