Antibiotic resistance has become
a global crisis in recent years,
while wastewater treatment plants (WWTPs) have been identified as
a significant source of both antibiotic resistant bacteria (ARB) and
antibiotic resistance genes (ARGs). However, commonly used disinfectants
have been shown to be ineffective for the elimination of ARGs. With
the goal of upgrading the conventional UV disinfection unit with stronger
capability to combat ARB and ARGs, we developed a UV-assisted electrochemical
oxidation (UV-EO) process that employs blue TiO2 nanotube
arrays (BNTAs) as photoanodes. Inactivation of tetracycline- and sulfamethoxazole-resistant E. coli along with degradation of the corresponding plasmid
coded genes (tetA and sul1) is measured
by plate counting on selective agar and qPCR, respectively. In comparison
with UV254 irradiation alone, enhanced ARB inactivation
and ARG degradation is achieved by UV-EO. Chloride significantly promotes
the inactivation efficiency due to the electrochemical production
of free chlorine and the subsequent UV/chlorine photoreactions. The
fluence-based first-order kinetic rate coefficients of UV-EO in Cl– are larger than those of UV254 irradiation
alone by a factor of 2.1–2.3 and 1.3–1.8 for the long
and short target genes, respectively. The mechanism of plasmid DNA
damage by different radical species is further explored using gel
electrophoresis and computational kinetic modeling. The process can
effectively eliminate ARB and ARGs in latrine wastewater, though the
kinetics were retarded.