Aerosols in livestock production, including particulate matter, pathogens, microbes (i.e., endotoxins), and viruses are important to livestock health, disease transmission, worker health, and overall cost of production. As particulate matter is composed of organic substances it can absorb and contain gases, microorganisms (including viruses), and other agents that can enhance its biological activity and, therefore, increase the risk of health effects. A number of studies have shown high prevalence rates of respiratory illnesses in animal farmworkers due to particulate matter present in livestock production facility air. In addition, an outbreak within a herd can have devastating economic impacts on the farm and to the industry. According to the estimates made by the George Morris Centre, the Porcine Reproductive and Respiratory Syndrome (PRRS) is costing a minimum of 130 million dollars per year to the Canadian swine industry. Moreover, bacteria and viruses can be easily spread to other animals, as well as to human populations, during transport.
The reduction of particulate matter and microbes in livestock production are paramount to livestock health and productivity and to the health of those who work in these environments. A number of remedial techniques to control these contaminants in livestock barns have been reported. These techniques include oil spraying, modifying feeds, litter amendment, and exhaust air treatment. There are, however, few technologies currently available on the market for air quality control. Among these remedial technologies, the electrostatic precipitation (ESP) based technology has the potential to be a robust and economically viable technology to reduce airborne particulates and associated microbes and odour in animal buildings.
Electrostatic precipitators have been effectively used to remove fine particles in flue gases from industrial plants (e.g., power, cement, metal industries) for decades. Among the advantages of ESP are low-pressure drop, high gas capacity, low energy demand, and high collection efficiency for fine particles (> 99%). Despite its desirable characteristics, ESP application in removing particulate matter, odour, and microbes in livestock facilities, as well as its impacts on animal productivity, has not yet been fully explored and investigated. Preliminary laboratory and field studies, however, have demonstrated that ESP is capable of effectively reducing dust, gases, and bacteria in livestock barns.
Although the efficacy of ESP technology has already been investigated in a number of studies, its application in livestock production is still limited to the research stage. ESP efficacy in removing microbes in poultry barns has not yet been fully investigated and needs additional studies. Detailed economic analyses such as those that look into energy savings from reduced power requirements during winter and productivity gains from improved air quality against both ESP installation and operating costs are still lacking. Moreover, a remedy to the generation of ozone, which is a by-product from the ionization process, has not been considered in other previous related studies. Thus, the proposed research aims to evaluate the strategies (e.g., material type and configuration of charging electrodes, voltage level) in minimizing ozone production in larger scales such as in commercial poultry houses. More importantly, from industry perspectives, the Chicken Farmers of Saskatchewan (CFS) are interested in applying new techniques, such as ESP, to reduce dust and associated odour and microbes in poultry barns.
In the context of microbial deactivation/elimination, the current methods used in livestock facilities, including animal transport trailers, are disinfection with oxidizing agents (e.g., chlorine, formaldehyde, hydrogen peroxide), fogging with an organic acid, ultraviolet irradiation, and air filtration systems. However, drawbacks of these techniques are cost, odour, residual contamination, and toxicity. More recently, a chemical-free nano-technology-based method has been reported for foodborne bacteria inactivation. In this technique, engineered water nanostructures (EWNS) are generated through electrospraying condensed water vapour recovered from room air and has been found to be effective in inactivating bacteria due to the high electric charge per surface area at the nanoscale of the generated EWNS. This technique appears promising as a non-chemical method for microbial deactivation in livestock barns as water spray is also commonly used in these facilities for cooling animals and mitigating dust levels. However, this method has been tested only at lab-scales with foodborne bacteria and airborne transmitted pathogens. Thus, this project aims to evaluate the effectiveness of this method in deactivating microorganisms prevalent in livestock buildings and transport trailers.
Aims of the Project
The aims of this project:
- Reduce dust and microbes in livestock facilities, so as to reduce/eliminate risks and hazards and enhance health and safety in agricultural production.
- Improving and/or adapting existing technological advances for application in dust and microbial reduction in livestock facilities.
To achieve this project, the following objectives will be completed:
- Evaluate the efficiencies of ESP based air-cleaning techniques in removing dust in poultry houses in small, medium, and full-scale studies.
- Develop/adapt a nanospray-based technology in deactivating microbes in swine barns and investigate its potential application using a lab-scale electrospray.
- Evaluate the performance of electrospray in deactivating microbes in small and medium scale swine barns.
- Evaluate the performance of electrospray in deactivating microbes in swine transport trailers.
- Compare the results of ESP and nanospray studies to the results attained from the previously tested dust reduction strategies (i.e., oil sprinkling, v-scraper, and air treatment unit) to determine the most efficient, cost-effective, and feasible dust and microbial reduction method.
For further information about this project, please contact Program Manager Nadia Smith at 306-966-1648 or by email at email@example.com
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2019 - 2020 Year 1 Update
Aerosols in livestock production include dusts or particulate matter, pathogens, microbes and viruses all of which pose risks to both human, animal and rural community health. This research aims to evaluate the effectiveness of two emerging green technologies, electrostatic precipitation-based air cleaning technique and electro nano-spray, in dust reduction and deactivating microorganisms prevalent in livestock buildings and transport trailers.
During Year 1 of Activity 2, a pilot-scale electrostatic precipitator (ESP) study was conducted at the Poultry Research and Teaching Unit at the University of Saskatchewan. For the pilot-tests, 2,195 one-day-old chicks were randomly placed in one of two identical rooms - control or treatment - and raised under a floor housing system for 113 days. In the treatment room, commercially available electrostatic particle ionizers were used to remove dust, gases, and bacteria. In the control room, pullets (young chickens) were raised under typical conditions without the ESP. The results of these tests showed that the ESP-room had a 69% reduction in total dust, a 48% reduction in PM10 and a 44% reduction in PM2.5 as compared to the control room. Total bacteria count was also evaluated and the results showed a 33% reduction in bacteria at the beginning of the trial, but the reduction in bacterial concentration became less apparent with time.
To study the effects of nanospray, a laboratory-scale nanospray apparatus was developed. Preliminary tests on poultry barn bacteria showed up to 95% deactivation efficiency with the use of nanospray. Subsequent trials will be carried out in swine barns.
An informational bulletin for the project was also produced under the CANFARMSAFE bulletin Reduction of Aerosol Risks and Hazards in Livestock Production.
2020 - 2021 Year 2 Update
In Year 2, two lab-scale studies were conducted: one evaluated the efficacy of the nanospray system in decontaminating surfaces, while a second study assessed the efficacy of this technology in inactivating airborne bacteria.
EWNS (Nanospray) Lab-scale Trials
In both lab-scale studies, Escherichia coli (E. coli) was used as the representative bacteria for pathogens commonly found in livestock facilities. The first EWNS was performed by inoculating 5-cm diameter stainless-steel coupons with an E. coli solution. The stainless-steel coupons were employed to simulate swine barn surfaces, to evaluate the efficacy of the nanodroplets (EWNS) in inactivating microbes attached to surfaces. The inoculated coupon was then exposed to the EWNS under various operating conditions including liquid flow rate, pH of liquid, conductivity, exposure time, and voltage level and polarity. Each run of nanospraying lasted for an hour. Air samples from the chamber were collected three times over the 1-hour run.
The nanospray studies demonstrated that the nanospray system is effective at inactivating airborne bacteria (up to 69% reduction) and decontaminating surfaces (up to 99% reduction). Lower liquid flow rates resulted in higher microbial inactivation. A lower liquid flow rate indicates a longer contact time between the metal capillary and the liquid, resulting in a higher formation of electric charges.
ESP – Medium and Large Scale Studies
The electrostatic precipitator (ESP) trials demonstrated that the ESP system could substantially reduce dust in broiler houses by up to 62%, bacteria by up to 63%, and odour by up to 50%. However, no considerable reduction was found for ammonia (NH3) concentration, nor was there a substantial impact observed in the mortality and feed conversion ratio. In addition, the technology is very economical and can treat air even at high ventilation rates. The efficiency of the technology could be enhanced by integrating an effective cleaning method for the removal of the accumulated dust on collection surfaces and introducing more/additional collection surfaces.
The medium-scale study was conducted at the Research and Development Institute for the Agri-Environment (IRDA) in Quebec. The study consisted of two trials, one conducted in June 2020 and another in August 2020. In both trials, 150 broiler chickens were raised in either a treatment or control room. The large-scale ESP study was conducted at the Poultry Centre at the University of Saskatchewan using six identical environmentally-controlled rooms. Three treatment rooms (with ESP units) and three control rooms (without ESP units) were utilized for the single experimental trial. The trial was conducted in February 2021. Eight hundred broiler chickens were raised in each room during the trial.
For both the medium and large-scale trials, the highest dust reduction was observed at the beginning of the trial (when the ESP was just turned on). The reduction efficiency generally decreased as the trial proceeded, although fluctuations occurred, probably due to the accumulation of dust on collection surfaces. A similar trend (higher at the beginning of the trial) for odour reduction was also observed. Reductions of up to 57% were obtained for both culturable and total bacteria in the medium-scale trial and 63% for total bacteria in the large-scale trial. With the large-scale trial, total bacteria concentrations in the control and treatment rooms were nearly stable at the beginning of the trial and then started to increase towards the end of the trial, which also coincided with the decrease in reduction efficiency. The reduction in the removal efficiency for odour and bacteria towards the end of both trials could be due to the reduced reduction efficiency for dust caused by the high accumulation of dust on the collection surfaces. Owing to the organic properties of dust, odour and bacteria could be easily adsorbed to its surfaces. No substantial difference in mortality rates between control and treatment was observed as well as in feed conversion ratio. No substantial difference in ammonia (NH3) concentration was observed between control and treatment.