Chloride reinforces nanowire electrocatalytic peracetic acid filtration for inactivating oxidant-resistant bacteria: A sequential PAA reduction and chloride oxidation pathway.

Chlorination often fails to inactivate oxidant-resistant bacteria protected by extracellular polymeric substances (EPS) while generating disinfection by-products (DBPs). Although electrochemical activation of peracetic acid (PAA) provides a low-DBPs pathway with diverse reactive species for water disinfection, it is hindered by the persistence of residual organic acids. Herein, we reported a nanowire electrochemical strategy that leveraged ubiquitous chloride ions in water to integrate physical electroporation, reductive PAA activation, and oxidative chlorine production, enabling efficient and residue-controlled disinfection. Hydrogenated black TiO2 nanowire electrodes generated intense localized electric fields near nanowire tips, inducing cell electroporation that disrupted EPS layer and cell wall barriers for facilitating oxidant-induced cell lyses. Concurrently, the intense charge density near nanowire tips facilitated PAA reduction, Cl2 evolution, and organic acid mineralization, accompanied by singlet oxygen (1O2) production from PAA/H2O2-Cl2 reaction. Chloride reinforced nanowire electrocatalytic PAA process with a sequential PAA reduction and chloride oxidation pathway for inactivating various gram-negative/positive and oxidant-sensitive/resistant bacteria, particularly achieving 2-3 log higher removal of oxidant-resistant bacteria under comparable energy consumption to that in the absence of chloride. Mechanistic studies confirmed 1O2 as the dominant species, selectively targeting membrane components while suppressing Cl2 accumulation and the formation of common carbonaceous and nitrogenous DBPs. The robust disinfection efficiency demonstrated in complex lake water matrices underscored that electrochemical PAA disinfection in chloride-rich waters must explicitly account for the modulating role of chloride ions.