Biofilm bacteria inactivation by citric acid and resuspension evaluations for drinking water production systems.

The study investigates the inactivation of biofilm bacteria colonized on the surface of polyvinyl chloride (PVC) pipes delivering either groundwater or treated wastewater. It does so using a citric acid (C6H8O7) solution. The results of the study showed that the optimal conditions of the biofilm bacteria inactivation were over 10,000 mg/L citric acid concentration and 60 minutes of contact time at least. Under these conditions, the removal efficiency could reach above 99.999% for heterotrophic plate count (HPC) bacteria and 99.95% for coliform bacteria. The study also showed that the biofilm bacteria were the major sources of planktonic bacteria resuspended into water purified by drinking water production systems (DWPS).