Ozone-based pipeline disinfection in Water Supply Systems: A pilot study on secondary microbiological risk reduction

Secondary water contamination in the distribution subsystem causes interruptions in its supply due to the necessity of undertaking corrective actions such as flushing and disinfecting the water supply network. Preventing events that generate secondary contamination of water, as well as implementing effective flushing and disinfecting procedures, remains a key challenge for water suppliers, as it directly contributes to increasing the security of drinking water provision. A promising solution to this problem is the application of a mobile F&DS (Flushing and Disinfection System), which produces degassed, highly ozonated water and injects it into the pipeline under conditions of microbiological contamination. The research was conducted on a fractional-technical scale using two model systems: a test stand with an operated steel section of the distribution network with sediment deposits, and a test stand with a new PE water pipe free from deposits. In the experiments, the influence of water pH, chloride concentration and water temperature on the effectiveness of ozone-based disinfection was assessed. The results confirmed that ozone enables effective inactivation of the tested microorganisms within a few minutes, thereby allowing water supply to consumers to be safely restored within just a few hours.