Analysis of the impact of the advanced oxidation processes on reclaimed water microbiological safety

The ReNutriWater project (Interreg Baltic Sea) evaluated the feasibility of reusing treated municipal wastewater for urban applications, with a particular focus on the irrigation of green areas [1]. As part of this initiative, a pilot-scale water reclamation system was implemented at the Savonia University of Applied Sciences in Kuopio, Finland. The system was designed to treat effluent from two municipal wastewater treatment plants, both of which produce effluent compliant with EU regulatory standards. This study investigates the microbiological safety and overall performance of the pilot system, with an emphasis on Escherichia coli ( E. coli ) as an indicator of fecal contamination. The reclaimed water was assessed against multiple regulatory benchmarks, primarily EU Regulation 2020/741. Results revealed considerable fluctuations in E. coli concentrations, indicating that a single-stage disinfection process may be inadequate to ensure microbiological safety under all conditions. In addition, the influence of operational and environmental parameters, especially temperature, on treatment efficiency was analyzed. The findings highlight the critical role of temperature in determining reclamation performance and suggest that seasonal and site-specific factors must be considered when designing systems for urban water reuse. Overall, the study contributes valuable insights into optimizing water reclamation processes to support safe and sustainable urban applications. • ReNutriWater project results show that water recovery on a small scale is possible. • It is necessary to control the microbiology in the reclaimed water, especially E.coli. • Weather conditions affect the effectiveness of disinfection. • One type of disinfection may not be enough to achieve appropriate water safety.