Investigation of a new UVC LEDs array continuous type water disinfection system for inactivating Escherichia coli O157:H7 according to flow rate and electrical energy efficiency analysis

Abstract

Abstract UVC LEDs are gaining popularity for its advantages which compensate for the limitations of low-pressure mercury UV lamps. In order to investigate the efficacy of UVC LEDs-based continuous water disinfection system, various numbers of UVC LEDs chips were introduced to inactivate Escherichia coli O157:H7 in water. Also, the effect of an aluminum reflector in the irradiation system was investigated in order to enhance bacterial inactivation. Without the reflector, the pathogen inactivation profile showed a sigmoidal curve, while linear fitting was shown for the treatment with the reflector, and there was a 1.5 times greater bactericidal effect when the reflector was installed. Based on the inactivation rate constant, no significant differences were revealed among the UVC LEDs chip arrays. Electrical energy efficiency necessary for 3- and 5-log reductions were calculated and the 18 UVC LEDs chip array consumed 30% less energy compared to the 33 UVC LEDs array. In this study, kinetic profiles of E. coli O157:H7 in a continuous water disinfection system using UVC LEDs irradiation with or without a reflector under various operational currents were obtained. Electrical energy consumption was considered in order to optimize the efficacy of this disinfection system. These results can be used as practical database to develop a water disinfection system using UVC LEDs and attributed to water and food safety.