Dose Distribution Scaling and Validation of Ultraviolet Photoreactors Using Dimensional Analysis

Area of Science:

• Environmental Engineering
• Water Treatment Technologies
• Disinfection Science

Background:

• Ultraviolet (UV) disinfection is crucial for drinking water and wastewater treatment.
• Current UV disinfection system design relies on empirical methods, which are costly and offer limited insight into photoreactor behavior.
• System performance is dictated by UV dose distribution, a key reactor characteristic.

Purpose of the Study:

• To develop a novel dose distribution scaling method for UV disinfection systems.
• To enable accurate prediction of UV photoreactor performance across various operating conditions.
• To provide a cost-effective and rapid alternative to conventional design and validation approaches.

Main Methods:

• Dimensional analysis, specifically the Buckingham-π theorem, was employed to develop the scaling method.
• Three dimensionless groups were defined: UV dose, reactor geometry, and UV absorption.
• The method was validated against 15 operating conditions, varying flow rate, UV transmittance, and lamp power.

Main Results:

• The developed scaling approach accurately predicted UV dose distribution across different operating conditions.
• Predictions of disinfection efficacy against MS2 and *E. coli* showed close agreement with conventional Computational Fluid Dynamics-based modeling.
• The method successfully scaled dose distribution with dimensionless variables representing flow rate, UV transmittance, and lamp power.

Conclusions:

• The proposed dose distribution scaling method offers a low-cost, rapid approach for predicting UV disinfection system performance.
• This method is applicable across a wide range of operating conditions and microbial agents.
• The findings provide a valuable tool for optimizing UV disinfection system design and operation.