Optimizing energy budget for UV driven biofilm prevention using response surface methodology

Biofouling presents significant challenges in engineered surfaces, including reduced optical clarity of transparent surfaces, increased surface roughness, and compromised functionality of underwater sensors, observation windows, and cameras. UV-emitting glass (UEG) technology provides an innovative solution to biofouling by targeting the attachment surface, effectively disrupting microbial adhesion and growth. However, UEGs performance is highly dependent on design choices and operational parameters. This study uses Response Surface Methodology (RSM) to optimize UEG performance in fouling control, enabling a deeper understanding of how UV irradiance and daily exposure time affect biofilm formation for submersion durations between 5 and 30 days. Although energy budget (EB) generally increases with Log reduction Value (LRV), there is no significant relationship between the two. Therefore, it is important to select the exposure time and UV irradiance that results in the lowest energy budget for a given submersion duration and goal LRV. The UV irradiance and exposure time resulting in lowest energy budget for LRV > 2 is reported for submersions of 1 – 3 weeks. A feasible range of parameters yielding LRV > 2 at minimum EB was identified. For two weeks, a 63 Wh/day/m 2 (34.4 Wh/day/m 2 /N log) was achieved for 2.2 LRV at a UV irradiance of 23 µW/cm² for 840 minutes per day. The LRV and EB were validated for these conditions and both biofilm coverage and morphology were characterized. Interestingly, although LRV and coverage decreased as expected, the biofilm thickness of the control and UV units were statistically the same illustrating that UV light prevents initial attachment but not subsequent growth. Visualization of optimal parameter space for LRV > 2 within the target EB n range. The white region denotes combinations of the studied variables that yield LRV > 2 while maintaining EB n within 18.5 – 40 Wh/day/m². • RSM framework optimizes UV biofilm control while minimizing energy budget • Weak EB-LRV correlation (R²=0.52) challenges simple dose-response models • Optimized conditions achieved >99% coverage reduction at 63 Wh/day/m² • UV disrupts attachment but not growth of established biofilm clusters • Biofilm prevention peaks at 18 days and longer submersion reduces efficacy