Removal of pathogenic indicator microorganisms during partial nitrification: the role of free nitrous acid

Digested wastewater contains pathogenic microorganisms and high ammonia concentrations, which can pose a potential risk to public health. Effective removal of pathogens and nitrogen is crucial for the post-treatment of digested wastewater. Partial nitrification-anammox is an energy-saving nitrogen removal process. Free nitrous acid (FNA), an intermediate product of partial nitrification, has the potential to inactivate microorganisms. However, the efficiency and mechanisms of FNA-related inactivation in pathogens during partial nitrification remains unclear. In this study, Enterococcus and Escherichia coli (E. coli) were selected to investigate the efficiency and mechanisms of FNA-related inactivation in partial nitrification process. The results revealed that 83