Optical fluence modelling for ultraviolet light emitting diode-based water treatment systems

Area of Science:

• Optics
• Environmental Engineering
• Microbiology

Background:

• Ultraviolet light-emitting diodes (UV-LEDs) offer versatile solutions for water treatment due to their tunable wavelengths and source geometries.
• Accurate modeling of optical fluence rate is crucial for optimizing UV-LED water disinfection systems.
• Existing models may not fully account for complex optical phenomena within treatment chambers.

Purpose of the Study:

• To develop and validate a robust optical fluence rate model for UV-LED water treatment units.
• To incorporate factors like reflections, scattering, and varying chamber designs into the model.
• To assess the model's predictive capability using experimental data.

Main Methods:

• Utilized a Monte Carlo approach with an incremental ray-tracing algorithm.
• Calculated local volumetric rate of energy absorption and converted it to local fluence rate distribution.
• Included optical reflections from chamber walls and scattering from particulates/microorganisms.
• Validated the model using biodosimetry with MS-2 bacteriophage and inactivation data for E. coli at 254 nm.

Main Results:

• The model successfully predicted optical fluence rates in point-of-use UV-LED water treatment units.
• Model predictions were consistent with experimental biodosimetry results.
• The model effectively accounted for the impact of different chamber geometries on UV disinfection efficacy.

Conclusions:

• The developed optical fluence rate model is validated and suitable for UV-LED water treatment applications.
• The model can be applied to the design and optimization of UV-LED water purification systems.
• Accurate fluence rate prediction is essential for ensuring effective microbial inactivation in UV water treatment.