Design and Development of a UV Reactor Integrated with a Microfiltration Module for Removal of Somatic Cells and Inactivation of Bacteria in Raw Milk

Abstract

This study focuses on the design, development, and evaluation of a hybrid ultraviolet–microfiltration (UV–MF) module for improving the microbial quality of raw milk while maintaining its overall quality. The system was developed by integrating a 3 µm microfiltration unit with two custom-fabricated UV-C reactors arranged in series to overcome the limitations of low UV transmittance in milk. Reactor 1 was designed with a 28 W UV lamp and a 3.5 mm annular flow gap, while Reactor 2 incorporated a higher-power 62 W lamp with a reduced 2.0 mm flow gap to enhance UV exposure under continuous flow conditions. Both reactors were fabricated  using food-grade stainless steel and quartz sleeves to ensure hygienic operation, leak-proof performance and ease of maintenance. The microfiltration stage acted as a critical pre-treatment by reducing turbidity and somatic cell load, thereby improving UV treatment efficiency. Limited performance evaluation indicated effective bacterial reduction, unchanged milk composition, delayed acidity development and acceptable sensory quality, demonstrating the suitability of the developed UV–MF system as a compact and non-thermal processing approach for dairy and food applications.