Performance Evaluation of a Pilot Scale Dean Flow UV System: Fundamentals and Applications

Pranav Vashisht, Tennessee State University


Mitigating the risk of introducing an adventitious contaminant during upstream processes of liquid foods manufacturing is critical. Although the inactivation of microorganisms in water and high transmittance liquid foods have been studied extensively, the efficiency of the process is rather poor for treating opaque liquid foods using traditional UV systems. This study evaluated the ability of UV-C light to inactivate foodborne pathogens in opaque fluids using a pilot-scale Dean Flow UV system. Simulated fluids inoculated with MS2 bacteriophage were used to test the system’s efficiency and assess the boundary conditions. A mathematical model was developed as a function of optical attenuation coefficients (abs. coefficient: 6.5 to 17 cm-1) and flow rates (31.70, 63.40, 95.10 gph). It was observed that REF scaled up linearly as an inverse function of flow rate and absorbance (R2 > 0.99, p < 0.05), indicating efficient mixing in the reactor. The algorithm was further tested and validated against independent experiments using S. Typhimurium and B. cereus. The predicted and experimental inactivation results were in close agreement, p>0.05 which demonstrated that the developed model can predict the REF, thus microbial inactivation in simulated fluids within the model boundary conditions. The system was improved for its transmittance and penetration efficiency and tested against WM inoculated with B. cereus. The REF delivered in WM was quantified at flow rates of 11.88, 23.77, and 47.55 gph. Among all the experimental flow rates, at 47.55 gph, the highest REF rate was observed attributed to the turbulence and Dean effect shown by high Reynolds and Dean number. Microbial inactivation studies conducted at 47.55 gph showed 0.91 ± 0.15 and 2.14 ± 0.19 log reduction per pass for B. cereus and T1 phage. It was envisaged that linear inactivation trends were observed, which demonstrates high mixing during each pass. A lower EEO value signifies the higher electrical efficiency of the system. No significant alteration in volatile profile and lipid peroxidation (p>0.05) was observed at UV-C fluence of 60 mJ/cm2, sufficient to inactivate >6-log of B. cereusand >12-log of T1 phage. This demonstrated the efficiency of UV-C to inactivate a range of pathogens without altering the quality of WM.

Subject Area

Food Science|Animal sciences|Fluid mechanics

Recommended Citation

Pranav Vashisht, "Performance Evaluation of a Pilot Scale Dean Flow UV System: Fundamentals and Applications" (2021). ETD Collection for Tennessee State University. Paper AAI28775804.