Aerosol formation during foam application of non-volatile biocidal substances

The application of biocidal products by foam is considered an alternative to droplet spraying when disinfecting surfaces or fighting infestations. Inhalation exposure to aerosols containing the biocidal substances cannot be ruled out during foaming. In contrast to droplet spraying, very little is known about aerosol source strength during foaming. In this study, the formation of inhalable aerosols was quantified according to the aerosol release fractions of the active substance. The aerosol release fraction is defined as the mass of active substance transferred into inhalable airborne particles during foaming, normalised to the total amount of active substance released through the foam nozzle. Aerosol release fractions were measured in control chamber experiments where common foaming technologies were operated according to their typical conditions of use. These investigations include foams generated mechanically by actively mixing air with a foaming liquid as well as systems that use a blowing agent for foam formation. The values of the aerosol release fraction ranged from 3.4 × 10-6 to 5.7 × 10-3 (average values). For foaming processes based on mixing air and the foaming liquid, the release fractions could be correlated to the process and foam parameters such as foam exit velocity, nozzle dimensions, and foam expansion ratio.

Flow effects on the surface properties of surfactant foam films

The surface electrostatic properties of liquid foam, involving the electrokinetic (EK) phenomena in the liquid-gas interface, have significant effects on the stability of the foam. Here, we established a theoretical model for ion transport in liquid films by combining the liquid flow and surface reaction. We found that the surface electrostatic properties of liquid foams were influenced unexpectedly by the pressure-induced flow. The liquid flow will induce the potential and concentration differences in the flow direction. When the pressure drop increases to a certain high value, the induced potential and salt concentration difference increases, leading to the change of the surface electrostatic properties such as zeta potential and the surface charge density. This change shows that the surface electrostatic properties of foam films depend on the coupling of various factors including ion distribution and pressure drop, which deepens our understanding of the electrostatic properties of the foam films.

Use of Foaming Disinfectants and Cleaners to Reduce Aerobic Bacteria and Salmonella on Poultry Transport Coops

Simple Summary

Chicken coops are rarely washed and can soil poultry carcasses with fecal bacteria that may make people sick. Our laboratory applied two commercially available products to experimentally contaminated coops. One product contained bleach, potassium hydroxide and a foaming agent. The other product contained vinegar and hydrogen peroxide and was mixed with a detergent. Both products were applied using a firefighting apparatus known as a compressed air foam system (CAFS). These materials were washed away using a garden hose or pressure washer as the treatments called for. Surface swabs were collected prior to and after each treatment to determine the reduction of bacteria on the surface, which would be an indicator of sanitation. We found that both treatments significantly made the surface cleaner when compared to water alone. The application of these products via a CAFS may be a practical and expedient way to clean and disinfect poultry cages.

Abstract

Transport coops are infrequently washed and have been demonstrated to cross-contaminate broiler carcasses. We hypothesized that peracetic acid or a chlorinated cleaner, commonly used within poultry processing plants, can also be used to disinfect transport coops when applied via a compressed air foam system (CAFS). A mixture of fresh layer manure and concentrated Salmonella Typhimurium (ST) was evenly applied to the floors of four pre-cleaned transport coops and allowed to dry for thirty minutes. Treatments consisted of a (1) water rinse only, (2) product application with a water rinse, (3) product application followed by power washing and (4) power washing followed by application of product. Each foaming treatment was applied with a compressed air foam system and allowed 10 min of contact time. Samples were aseptically collected from the transport coops prior to and following treatment using a sterile 2 × 2-inch stainless steel template and a gauze swab pre-enriched with buffered peptone water. The chlorinated cleaner significantly (p < 0.05) reduced aerobic bacteria and ST by 3.18 to 4.84 logs across application methods. The peroxyacetic acid (PAA) disinfectant significantly (p < 0.05) reduced aerobic bacteria and ST by 3.99 to 5.17 logs across application methods. These data indicate that a compressed air foam system may be used in combination with a commercially available cleaner or disinfectant to reduce aerobic bacteria and ST on the surfaces of commercial poultry transport coops.