Removal of antibiotic resistant bacteria and genes by nanoscale zero-valent iron activated persulfate: Implication...

Area of Science:

• Environmental Science
• Water Treatment
• Microbiology

Background:

• Persulfate activation typically relies on reactive oxygen species (ROS) for removing antibiotic resistant bacteria (ARB) and genes (ARGs).
• The role of pH changes in persulfate-based systems for ARB and ARGs removal remains under-investigated.

Purpose of the Study:

• To investigate the efficiency and mechanism of removing ARB and ARGs using nanoscale zero-valent iron activated persulfate (nZVI/PS).
• To evaluate the contribution of decreased pH to the removal of ARB and ARGs in the nZVI/PS system.

Main Methods:

• Utilized nanoscale zero-valent iron (nZVI) to activate persulfate (PS) for water treatment.
• Quantified removal efficiencies of ARB, sul1, and intI1 genes using nZVI/PS.
• Investigated the dominant ROS and analyzed the impact of pH reduction on ARB and ARGs removal.

Main Results:

• Complete inactivation of ARB (2 × 10^8 CFU/mL) within 5 min and high removal efficiencies for sul1 (98.95%) and intI1 (99.64%) were achieved with nZVI/20 mM PS.
• Hydroxyl radicals were identified as the primary ROS responsible for ARB and ARGs removal.
• The nZVI/PS system significantly decreased pH to 2.9, which independently contributed to substantial ARB (60.33%), sul1 (73.76%), and intI1 (71.51%) removal.

Conclusions:

• nZVI/PS is highly effective for removing ARB and ARGs, primarily through hydroxyl radical generation.
• The significant pH decrease in the nZVI/PS system is a crucial, previously underappreciated factor contributing to ARB and ARGs removal.
• This research highlights the dual mechanism of ROS and pH reduction in advanced oxidation processes for combating antibiotic resistance.