Inactivation of antibiotic resistant bacteria from stormwater runoff using UVA/LED and its potential risks

Recently, increasing attention has been paid to antibiotic resistance in stormwater runoff. However, there is no available literature about the control of antibiotic resistant bacteria (ARB) through 365 nm ultraviolet light-emitting diode (UVA/LED). In this study, batch experiments were conducted to investigate ARB inactivation kinetics, effects of light intensity and water matrix (including suspended solid (SS) concentration, initial pH and bacteria concentration), and potential transmission risks after UVA/LED irradiation. Results showed that ARB inactivation efficiencies reached 6.31 log reduction at 8 mW/cm(2) (86 J/cm(2)) of UVA/LED for 180 min. ARB inactivation efficiencies increased with the increase of light intensity, and showed a linear relationship. ARB inactivation decreased with increasing SS levels, and the largest inactivation efficien-cies was 3.56 log reduction at 50 mg/L of SS. Initial pH had slight effect on ARB inactivation through UVA/LED irradiation. A low initial bacteria concentration (10(5) CFU/mL) was not necessarily associated with good ARB inactivation (3.59 log reduction). After UVA/LED irradiation, ARB was hardly detected during 12 hr of dark repair, and the transfer frequency of kanamycin resistance gene was increased to 5.43 x 10(-4). These suggested that the application of UVA/LED to inactivate ARB in stormwater runoff was feasible and desirable in this study.

Automated summary

This study investigated the use of 365 nm ultraviolet light-emitting diode (UVA/LED) to control antibiotic resistant bacteria (ARB) in stormwater runoff. The results showed that UVA/LED irradiation effectively reduced ARB levels, and the inactivation efficiency was influenced by light intensity and suspended solid (SS) concentration. Initial pH had minimal impact on ARB inactivation. Additionally, the study found that after UVA/LED irradiation, ARB was hardly detected during a 12-hour dark repair period, and the transfer frequency of kanamycin resistance gene increased.