Nanospike-enhanced synergistic disinfection of adsorption-puncture-oxidation for real wastewater reclamation

Current single-mechanism disinfection methods in wastewater reclamation process often fail to eliminate the broad-spectrum persisters (e.g., disinfection residual bacteria, DRB), posing latent public health risks. Integrating multiple disinfection methods has becoming a compelling strategy, yet the low-cost, high-efficiency and resilient disinfection methods are still lacking. Here, we synthesized the powerful CuO/ZnO nanospikes with positively charged surfaces and photocatalytically active heterojunctions, which can inactivate (pathogenic) DRB via the adsorption-puncture in dark-phase and synergistic adsorption-puncture-radical oxidation mechanisms in light-phase. The CuO/ZnO nanospikes achieved significant bacterial inactivation from low dosages (10–50 mg/L) under short contact time (7 log reduction within 3 min for Bacillus subtilis and Escherichia coli), and showed less interference in faced with organic nutrients and inorganic ions. The physical adsorption-puncture induced the rapid increase in cell membrane permeability. On this basis, CuO/ZnO generated singlet oxygen and superoxide radicals under visible light excitation, which induced significant oxidative stress and downregulated the genes associated with multi-targets, including energy metabolism, DNA replication and repair, and protein synthesis. Various DRB and antimicrobial resistance genes (ARGs) were simultaneously inactivated 1–2 log in actual reclaimed water. Specifically, Acinetobacter radioresistens that carries 15 ARGs, a representative disinfectant-resistant bacterium, was sufficiently removed by 2 log and lost all the ARGs after disinfection. The continuous-flow system sustained stable disinfection for 24 h and satisfied local reclaimed water standards. This study offers a promising point-of-use disinfection strategy for middle-and low-income regions.