Investigating Efficiency of Engineered Water Nanostructures (EWNS) Generated via Electrospray Technique to Deactivate Surface Microbes in Livestock Barns

Abstract

Electrospray has been studied for more than two centuries in applications such as drug delivery and air purification, and to study basic principles behind mass spectrometry electrohydrodynamic atomization. More recently, electrospray systems have been used to generate engineered water nanostructures (EWNS). EWNS are generated by concurrently electrospraying and ionizing water. During the production of EWNS, reactive oxygen species (ROS) are generated, these ROS have the ability to deactivate bacteria. As such, EWNS may be a promising chemical free surface decontamination method. The objective of the research work was to determine the optimal operating condition that produced the highest deactivation efficiency of prevalent bacteria in livestock barns. Pathogenic bacteria in livestock barns contribute to animal and human illness and disease, and a non-chemical decontaminating method, such as EWNS, would benefit the industry. To date there is no research investigating the optimal parameters for EWNS efficiency to deactivate bacteria. Parameters under study included the effect of pH, conductivity, distance between needle tip and counter electrode, water flow rate and voltage on the performance of EWNS. The research work was conducted in two phases. In phase I, a systematics study was undertaken to investigate the electrical current and electrosprayed area under a broad range of operating parameters including voltage level and polarity, pH, conductivity, needle tip to counter electrode distance and liquid flow rate. In phase II, the bacteria deactivation efficiency of EWNS for Escherichia.coli and poultry barn bacteria were investigated. The optimal EWNS operating condition that produced the highest deactivation efficiency (4 logs or 99.99%) for E.coli was -6.6 kV, 2 cm distance between needle tip and counter electrode, 2 µL/min, pH=7, K=0.20 mS/cm and 25 min of exposure time. Further, the results indicated that the nanospray technology is a potential chemical-free alternative to conventional methods (e.g., chlorine spraying) in decontaminating surfaces of livestock buildings. Scaling up the technology for larger scale applications and in-barn tests are required in future research.