Comprehensive assessment of electrochemical disinfection for real secondary effluent: more efficient with reduced...

Reliable disinfection of secondary effluent is essential to ensure the safe reuse of reclaimed water. However, while conventional free chlorine (FC) disinfection effectively inactivates pathogens, it concurrently introduces considerable secondary chemical risks. Electrochemical (EC) disinfection has emerged as a promising alternative, yet its performance in real secondary effluent and comprehensive comparison with FC remains to be fully evaluated. In this study, we systematically assessed the disinfection efficacy and disinfection by-product (DBP) formation of EC disinfection using real secondary effluent. A comparative framework based on effective chlorine equivalent dose was established to enable a fair comparison between EC and FC. The results demonstrated that EC disinfection outperformed FC by achieving more efficient, thorough, and readily monitored inactivation of endogenous microbial indicators and pathogens, underscoring its enhanced capability for microbial risk control. Regarding secondary chemical risks, even though EC treatment unexpectedly produced a higher total concentration of DBPs, the overall toxicity assessed by both computational and experimental methods was comparable to or even lower than that of FC. Moreover, a straightforward electrode inversion strategy was implemented, which significantly reduced DBP formation and associated toxicity without compromising disinfection performance, thus enabling synergistic control of microbial and secondary chemical risks. This study enhances the understanding of EC disinfection and its secondary chemical risks in real-world applications, laying a foundation for the development of advanced EC disinfection systems with dual-risk control capabilities and strong potential for engineering applications.