Water disinfection by the UVA/electro-Fenton process under near neutral conditions: Performance and mechanisms

An efficient and thorough water disinfection is critical for human health. In this study, UVA-LEDs, nitrilotriacetic acid (NTA) and a boron-doped diamond anode were respectively used as the UVA source, the iron chelator and the anode for the UVA/electro-Fenton (E-Fenton) reaction to treat wastewater. The disinfection performance of the UVA/E-Fenton had been investigated. The mechanisms of the E. coli inactivation had been clarified. The results showed that complete disinfection (about 5.6-log removal) could be achieved within 50 min at a certain condition due to the synergistic effort of the UVA, anodic oxidation and the electro-Fenton. The quenching experiments and the electron paramagnetic resonance (EPR) detection indicated that center dot OH, center dot O2 and 1O2 play important roles for inactivating E. coli. The results of SEM images and genomic DNA electrophoresis suggested that both the cell structure and the DNA had been thoroughly destroyed during the UVA/E-Fenton process. Increasing the UVA irradiation, oxygen bubbling could improve the disinfection rate, while it also would increase the energy consumption. The appropriate Fe and NTA ratio was 1:2 to realize an efficient Fenton reaction under near neutral condition. Complete disinfection was also achieved within 50 min when it used for treating real wastewater. Thus, the UVA/E-Fenton process is a satisfied way for water disinfection.

Automated summary

Efficient and thorough water disinfection is crucial for protecting human health. This study investigated the use of UVA-LEDs, nitrilotriacetic acid (NTA), and a boron-doped diamond anode in the UVA/electro-Fenton (E-Fenton) process to treat wastewater. The research found that the synergistic effect of UVA, anodic oxidation, and electro-Fenton can achieve complete disinfection within 50 minutes, with important reactive species like •OH, •O2, and 1O2 playing key roles in E. coli inactivation. The UVA/E-Fenton process was also found to effectively destroy cell structure and DNA. The study concluded that this process is a satisfactory method for water disinfection.