Real-Time Monitoring of Dose Distribution and Simplified Indicators of Ultraviolet Reactors with a Buckingham-π Theorem-Based Dual MFSD System.

Real-time monitoring of dose delivery is critical for ensuring reliable and energy-efficient ultraviolet (UV) disinfection. However, conventional methods are limited by high cost and inability to capture full dose distribution information. This study presents a novel, cost-effective approach for real-time monitoring of UV dose delivery (including dose distribution and simplified indicators) by integrating a dual microfluorescent silica detector (dual-MFSD) system with Buckingham-π theorem-based scaling. The dual-MFSD system enabled simultaneous and convenient monitoring of real-time water UV transmittance (TRT), as well as a correction factor (CFRT) accounting for lamp output attenuation and sleeve fouling, with an effective optical path-length difference calibrated as 1.01 cm. A dimensionless scaling method based on the Buckingham-π theorem was developed to predict full information of the UV dose distribution using real-time operating parameters (i.e., TRT, flow rate (QRT), and CFRT), allowing rapid calculation of simplified indicators. The predicted doses were validated by computational fluid dynamic (CFD) simulation and biodosimetry at various TRT values (97% and 90%) and QRT values (40, 50, and 60 L min-1) with a measured CFRT (0.754). Additionally, a four-month field test was conducted in a secondary water supply system, demonstrating the practical applicability of this method. This study provides a real-time approach for UV dose monitoring, supporting reliable and energy-efficient UV disinfection.