Monitoring and optimization of wastewater disinfection processes for ecosystem preservation

A year-long monitoring initiative in northern Italy evaluated wastewater disinfection efficiency on E. coli and its impacts on the aquatic environment of the surface recipients, in terms of microbiological quality and ecotoxicity. Results showed significant differences in E. coli concentration between the effluent and the surface water upstream the discharge point, with most WWTPs having better quality compared to the recipients. Residual disinfectants, particularly sodium hypochlorite, exhibited higher dosed concentrations and eco-toxicity compared to peracetic acid. Finally, a mass balance and decay model approach have been formulated to support in setting discharge limits to mitigate ecotoxicity and by-product formation, crucial for public health and environmental integrity.