Experimental and computational evaluation of a flow-through UV-LED reactor for MS2 and adenovirus inactivation

Abstract

The design of efficient ultraviolet light emitting diode (UV-LED) reactors is of paramount importance for delivering a high UV dose (fluence). This is particularly critical to the disinfection of UV-resistant organisms, such as adenovirus, in continuous UV systems, given the low wall plug efficiency of UV-LEDs. The UV-LED offers reactor design flexibility, allowing to conform the reactor fluence rate to its hydrodynamics to a high degree, leading to improved design efficiency. In this study, we designed and fabricated a flow-through multi-baffle UV-LED reactor containing 18 UV-LEDs for delivering high UV fluence to a flow of water. Further, we developed a computational model for simulating the reactor performance, to fine-tune the fluence rate and hydrodynamics conformity through exploring several design concepts. The model was evaluated by experimental studies using male-specific-2 (MS2) bacteriophage and adenovirus as the model UV resistance microorganisms. The radiant field was adjusted through the LED arrangement and radiation profile modification. The reactor performance was studied under six different LED arrangements, three irradiation modes, and flow rates of 0.75, 1, and 2 L min−1. Adenovirus inactivation at 1 L min−1 from 1.6 logs increased to 4.1 logs through radiant field modification and enhancing the design efficiency. It was observed that the flexibility offered by UV-LEDs in adjusting the radiation pattern and hydrodynamics could lead to the design of highly-efficient reactors through positively correlating the UV fluence rate profile with the velocity filed. This study presents a detailed discussion concerning irradiation methods and provides insights applicable to UV-LED reactor design.