New device for air disinfection with a shielded UV radiation and ozone

A. Martinovs¹*, L. Mezule², R. Revalds¹, V. Pizica¹, V. Denisova², A. Skudra³, G. Kolcs¹, E. Zaicevs¹ and T. Juhna²

¹Rezekne Academy of Technologies, Faculty of Engineering, Atbrivosanas aleja 115, LV-4601 Rezekne, Latvia
²Riga Technical University, Water Research and Environmental Biotechnology laboratory, P.V. Valdena 1-303, LV-1048 Riga, Latvia
³University of Latvia, Institute of Atomic Physics and Spectroscopy, Jelgavas iela 3, LV-1004 Riga, Latvia
*Correspondence: andris.martinovs@rta.lv

Abstract:

Indoor air disinfection has become particularly relevant recently because of the Covid-19 pandemics. A shielded device for air and surface disinfection with UV radiation and ozone has been developed. It contains 28 low intensity (11 W) UV lamps (254 nm) in a specially designed three-dimensional grid to provide a large flow cross-sectional area and long path for the air particles to be irradiated. The device can be used in medical institutions, veterinary clinics, manufacturing plants, public premises, poultry, and livestock farms. It does not generate air-ions and ozone concentrations do not exceed the allowed 8-hour average values. The large number of UV lamps and powerful fans ensure air disinfection in large rooms in a relatively short time (400 m3 h-1). Simultaneously, the floor surface under the appliance is disinfected. Disinfection efficiency tests demonstrated 99.9999% reduction for Escherichia coli, Staphylococcus aureus and Pseudomonas phage Φ6 aerosols within a single transfer through the system (10 seconds of treatment). The housing of the device protects from direct UV radiation; therefore, people can be in the room during the operation of the device.

Key words:

air ions, disinfection, ozone, prototype, UV radiation

Comparison of the effect of ultraviolet light, ozone and heat treatment on muesli quality

I. Lignicka*, A. Balgalve, K. Ābelniece and A.M. Zīdere-Laizāne

Felici LLC, Rigas gatve 8, LV-2164, Adazi, Adazu novads, Latvia
*Correspondence: ilva.lignicka@musli.lv

Abstract:

Various muesli processing technologies can be used to lower microbiological parameters. It is necessary to find the best treatment technology to ensure that the product can meet various regulatory limits and to increase the shelf life of the product. The aim of this study was to compare the effect of ultraviolet light, ozone treatment and sterilisation on muesli quality. Muesli samples with dried fruits were tested, comparing the change in total plate count, yeast count and mould count. Short-wave ultraviolet (UV-C) light with a wavelength of 254 nm was used for ultraviolet light treatment, and the product was treated for 1, 2, and 5 minutes. As for ozone treatment, the samples were treated with an ozone concentration of 35 ppm for 30 minutes. Heat sterilisation was performed using sterilisation mode 25-30-50 (heating, holding, cooling), 119 °C, 2.2×10⁵ Pa. Ultraviolet light and ozone treatment did not have a significant impact on total plate count, yeast count and mould count. Heat sterilisation had the most significant effect on muesli sample microorganism level, total plate count, yeast count and mould count level were 10 log cfu g^-1.

Key words: