Optimizing Uvc-Disinfection Using Leds as an Energy Efficient Pre-Treatment for Biofouling Control in Spiral Wound Membrane Systems
28 Pages Posted: 17 Jan 2023
Abstract
Biofouling remains a major challenge for reverse osmosis (RO) systems. Pulsed ultraviolet (UV) pre-treatment have been proposed as a mitigation strategy for biofouling control of RO membranes. This study investigated whether increasing fluence rate during pulsed UV disinfection leads to enhanced inactivation. Further, UV irradiation from 1.5 to 61.3 mJ cm-2 was tested for optimal biofouling control. Therefore, an UVC-LED flow-through reactor was characterized by using actinometry. The inactivation of microorganisms was compared in flow-through biodosimetry experiments in pulsed and continuous irradiation. Finally, several settings were applied as pre-treatment in lab-scale biofouling experiments, and membrane performance and biofilm removability elucidated. Whereas no enhanced inactivation was observed during biodosimetry experiments, pulsed UV disinfection resulted in an average of 20.6% increased delay of biofilm formation compared to continuous irradiation. On the contrary, for pulsed UV disinfection, biofilm hydraulic resistance was higher than continuous equivalents. Overall, saving of operational expenditures per power used for LED probably is highest in the range of 4 to 28 mJ cm-2 and the pulsed setting at 1.4% duty cycle was 24.6% more efficient than the equivalent continuous setting. UV pre-treated biofilms showed no enhanced removability, but delay in biofilm formation was noticeable in two of three experiments.
Keywords: Ultraviolet irradiation, Chemical actinometry, biodosimetry, Biofouling, Reverse osmosis
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