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Improving Air Quality in Broiler Rooms Using an Electrostatic Particle Ionization System
Myra Martel1, Shelley Kirychuk2, Bernardo Predicala3, Roger Bolo1, Yingjie Yang1, Brooke Thompson4, Huiqing Guo5, Lifeng Zhang1,*
Published in Journal of the ASABE 66(4): 887-896 (doi: 10.13031/ja.15291). Copyright 2023 American Society of Agricultural and Biological Engineers.
1Chemical and Biological Engineering, University of Saskatchewan, Saskatoon, Saskatchewan, Canada.
2Medicine, University of Saskatchewan, Saskatoon, Saskatchewan, Canada.
3Prairie Swine Centre Inc., Saskatoon, Saskatchewan, Canada.
4Canadian Centre for Health and Safety in Agriculture, University of Saskatchewan, Saskatoon, Saskatchewan, Canada.
5Mechanical Engineering, University of Saskatchewan, Saskatoon, Saskatchewan, Canada.
*Correspondence: Lifeng.zhang@usask.ca
The authors have paid for open access for this article. This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License https://creative commons.org/licenses/by-nc-nd/4.0/
Submitted for review on 3 August 2022 as manuscript number PAFS 15291; approved for publication as a Research Article by Associate Editor Dr. Garey Fox and Community Editor Dr. Shafiqur Rahman of the Plant, Animal, & Facility Systems Community of ASABE on 26 April 2023.
Highlights
Abstract. Air quality in poultry operations is important for animal and human health. This study evaluated an electrostatic particle ionization (EPI) system for improving air quality in mechanically ventilated broiler rooms (11.7 m long, 6.4 m wide, and 2.9 m high), each with 800 birds. The study evaluated the impact of the EPI system on the levels of particulate matter (PM), ammonia (NH3), and hydrogen sulfide (H2S), as well as on animal performance. On average, the EPI system reduced PM fractions (PM1, PM2.5, PM4, PM10, and PM15) by approximately 50%. Average reductions for total PM and bacteria were 40% and 48%, respectively. No significant reduction was observed for NH3, and no measurable H2S was detected during the entire study period. No significant effects on feed conversion ratio and animal mortality were observed. Reductions in PM and total culturable bacteria decreased over time, which could possibly be due to increased contaminant concentration, ventilation rate, and accumulated dust on collection surfaces towards the end of the rearing cycle. Further assessments are required to determine if additional EPI units or collection surfaces could improve the efficiency of the system. Overall, the system reduced airborne PM and bacteria and improved the air quality in broiler houses.
Air quality in livestock facilities is important to animal and human health. Total particulate matter (PM) levels of 9.6±7.9 mg m-3 have been measured in floor-housed poultry operations in Canada (Kirychuk et al., 2006). Levels often exceed exposure limits set in Canadian workplaces. Ontario, for instance, set an occupational exposure limit of 5 mg m-3 for total poultry dust (Government of Ontario, 2022). Higher prevalence of respiratory symptoms and lung effects in workers have been associated with poor indoor air quality in poultry barns (Kirychuk et al., 2006; Rimac et al., 2010; Viegas et al., 2013). Moreover, the complex nature of PM (shape, size, density, chemical composition) makes them a good carrier of bacteria, viruses, gaseous pollutants, and odorous substances (Tan and Zhang, 2004; Cambra-Lopez et al., 2009), which enhances their detrimental effects on the health of workers and animals. Hence, reducing PM can positively impact workers’ health as well as livestock health and productivity.
A variety of techniques have been tested and employed in animal buildings to control PM, such as water/oil spraying (Aarnink et al., 2011; Winkel et al., 2016), wet scrubbing (Almuhanna et al., 2009; Ru et al., 2017), filtration (Wenke et al., 2018; Lee et al., 2021), and electrostatic precipitation (Ritz et al., 2006; Cambra-Lopez et al., 2009; Jerez et al., 2013). Electrostatic precipitation for PM reduction involves ionizing the particles using high voltage current and collecting the charged particles on grounded surfaces. One of the advantages of this technique is low pressure drop as the collection force acts only on the particles and not on the entire air stream; thus, it has low energy demand and can handle high volume air flow (Chai et al., 2009; Brauer and Varma, 2012), such as in animal buildings.
In livestock facilities, electrostatic precipitation (ESP) has been used to reduce PM either inside the animal confinement areas (Mitchell et al., 2004; Cambra-Lopez et al., 2009; Jerez et al., 2013) or at the exhaust of the buildings (Winkel et al., 2012; Manuzon et al., 2014). This technique has been found to reduce PM, gases, odor, and bacteria in commercial broiler houses (Mitchell et al., 2004; Cambra-Lopez et al., 2009; Jerez et al., 2013). It has also been tested in removing pathogens in pig rearing facilities (Alonso et al., 2016). However, despite the promising results of this technique, its effectiveness can be affected by several factors, such as relative humidity, temperature, PM properties and concentration, air flow rate, and design parameters (Cambra-Lopez et al., 2009; Harmon et al., 2014; Nouri et al., 2016; Zheng et al., 2018).
These ESP studies were mostly conducted in animal facilities in the USA and Europe, where the climate may be different than in Canada, particularly in the cold winter of the Canadian Prairies. Because of these differences in climatic conditions, ventilation rates in these facilities may differ; thus, the effectiveness of the method may also differ. In addition, most of the ESP studies in animal facilities were conducted more than ten years ago. Because of the changes in animal genetics (Tavarez and de los Santos, 2016), feed and nutrition (Elwinger et al., 2016), and housing and management systems (Gillespie et al., 2017; Karcher and Mench, 2018) over the years due to consumer preferences, increased demands, profit maximization, and policy measures, it would be necessary to evaluate the technology under current broiler production systems and Canadian Prairie climatic conditions.
Thus, this study evaluated a commercially-available electrostatic particle ionization (EPI) system for the reduction of PM, bacteria, and gases in experimental broiler rooms in Saskatchewan, Canada, under a production system and management similar to those currently employed in commercial broiler farms. The results of this study can provide insight and help producers make informed decisions on the potential application of the technology in commercial broiler houses, as well as other types of poultry houses with similar setup and environmental conditions.
Materials and Methods
Housing and Animals
This study was conducted at the Poultry Research and Teaching Unit of the University of Saskatchewan, Saskatoon, Saskatchewan, from 16 February to 22 March 2021. Six identical mechanically ventilated broiler rooms were used, three of which were used as treatment rooms, where the EPI systems were installed, and three as control rooms. Each room was 11.7 m long, 6.4 m wide, and 2.9 m high (fig. 1), with a 59 m2 pen area used for the birds. Each room had two identical exhaust fans, each with a diameter of 0.46 m and a maximum capacity of approximately 2000 m3 h-1; however, the second fan worked only when the required ventilation in the room was higher than 50% of the first fan’s capacity. Part of the air in the room was recirculated using a circulation fan connected to a 9-m long polyethylene tube with properly-sized holes, which ran at the center of the room along its length, close to the ceiling (fig. 1). The rooms were heated using hot water pipes running along the walls.
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At the start of the experiment (Day 1), 800 one-day-old Ross 308 broiler chicks (mixed sex) were randomly assigned to each room at an anticipated density of 29.8 kg m-2 for a target marketable weight of 2.2 kg at the end of the 35-day experiment. The birds were raised in a floor-based system. Wheat straws with 10%-15% moisture content were used as litter, spread at a depth of approximately 7 cm, and were not replaced until the end of the experiment. The birds had free access to feed and drinking water. Each room had 12 feeders (six on each side of the room) and 12 drinking lines (six on each side). During the first five days of the experiment, supplemental feeders (paper egg trays) and drinkers (plastic chick drinkers) were provided. For the first 14 days, the birds were given a starter diet, followed by a grower diet (Days 15 to 24) and a finisher diet (Days 25 to 35). In the first seven days, the light intensity in each room was maintained at 20 lux and then reduced to 10 lux until the end of the experiment. The room temperatures were gradually decreased from 33°C on Day 1 to 20°C on Day 35. The study was approved by the Animal Research Ethics Board of the University of Saskatchewan (animal use protocol number 20210007).
Although the study was not conducted in a commercial poultry house, the physical setup and husbandry practices in the research facility were similar to those employed in commercial broiler barns. The stocking density employed (29.8 kg m-2) was within the recommended stocking density limit (31 kg m-2) set by the Canadian Codes of Practice (National Farm Animal Care Council, 2023). Additionally, equipment used for housing, feeding, watering, lighting, and ventilation were all comparable to those in the Canadian commercial industry. The operation of the facility, number of birds, type of feed, environmental settings, and daily care provided to the birds over the room cycle, mimicked industry settings and practices; thus, the levels of dust, gases, and other environmental parameters encountered during the study were similar to those in a larger commercial barn.
Electrostatic Particle Ionization System
This study used a commercially available EPI system, which consisted of stainless-steel corona pipes (fig. 1) (EPI Air, LLC, Olivia, MN) and a high voltage DC power supply (LHV Power Corp., Santee, CA). Each corona pipe was 1.8 m long, with an outer diameter of 25 mm, and had 25 mm long sharp stainless-steel corona points, spaced at a 50 mm distance and welded in “V”s along the length of the pipe. Ten corona pipes were installed in each treatment room (five on each side, connected end-to-end) and suspended 2.5 m above the litter, with sharp points pointing toward the litter. The corona pipes were then connected to the high voltage power supply, which generated -30 kV DC at a current level < 2 mA. The EPI system was operated only from the 2nd to the 4th week of the experiment; the data collected in the first week were used to confirm the similarity in the conditions between the control and treatment rooms, particularly in terms of PM concentrations, whereas those collected in the last week were used to assess any residual effects of the treatment on the monitored parameters. All the metal parts in the room were grounded and used as collection surfaces. The PM attached on the surfaces were removed only once over the entire duration of the trial using brooms, and the detached PM were collected in garbage bags.
Measurements
Ventilation Rates and Environmental Parameters
As mentioned earlier, each room had two identical exhaust fans, each with a diameter of 0.46 m and a maximum capacity of approximately 2000 m3 h-1; the second fan worked only when the required ventilation in the room was higher than 50% of the first fan’s capacity. The flow rate of the air passing through each exhaust fan at a particular fan speed setting was determined by measuring the air velocity at various sections of the fan (traverse method) across its cross section, then taking the average and multiplying it with the fan area (Air Movement and Control Association International Inc., 2016; Care et al., 2014). The measurements were performed prior to the start and at the end of the experiment, and the two values were averaged. The flow rates through the two fans in each room at each setting were
added, and a calibration curve was then created by plotting the sum of the air flow rates against the corresponding fan setting (fig. 2). The air flow rates during the experiment were estimated using the calibration curves and the actual fan speed settings. However, as the system could not store data, the fan speeds were viewed only from the control panel; hence, only daytime ventilation rates are available. Minimum fan speeds were pre-programmed prior to the start of the experiment; however, this could be overridden during the experiment depending on actual indoor and outdoor conditions.
The temperature and relative humidity in each room were monitored every hour using a temperature-relative humidity sensor, and the daily values were the averages of the 24 measurements.
Particulate Matter
Concentrations of PM fractions (PM1, PM2.5, PM4, PM10, and PM15) were monitored using a DustTrak aerosol monitor (DRX 8533, TSI; MN, USA), which detects particles with sizes ranging from 0.1 to 15.0 µm and measures concentrations ranging from 0.001 to 150 mg m-3. The sampling flow rate was 3.0 L min-1, and the data log interval was 1 s. Measurements in each room were conducted for 20 min twice a day, and the daily values are reported as the average of the two daily measurements. Samples were collected 1 m away from the exhaust at 1 m above the birds (fig. 1). Concentrations inside the room may vary with time and location; however, the chosen sampling frequency was deemed sufficient to be able to collect enough data to achieve the objective of this study (i.e., assess impact on bioaerosol levels), without causing added stress to the birds by frequently sampling more than necessary. In addition, it was assumed that the concentration at the exhaust, which was the common exit point, was the average concentration in the room and thus the most representative.
Two total PM (total suspended particulate) samples were collected in each room for 4 h (from 10:00-14:00), twice a week, using 37 mm closed-face filter cassettes loaded with a 37 mm polytetrafluoroethylene (PTFE) filter (1 µm pore size; SKC Inc., PA, USA) attached to air pumps (AirChek pumps, SKC Inc., PA, USA), which were calibrated prior to each sampling at a flowrate of 2 L min-1 (Method 0501; NIOSH, 2015) using a low-flow calibrator (Bios Defender 530 with ±1% accuracy; Mesa Laboratories, Inc., CO, USA). The flow rates were also verified after sampling using the same calibrator, and the average of the two flow rates (pre- and post-sampling) was used in the calculation of the PM concentration. The filters were conditioned in a desiccator for at least 24 h prior to weighing in a microbalance (MX5, Mettler-Toledo International Inc., Greifensee, Switzerland; 1 µg resolution) before and after sampling. The filters were weighed three times, and the average was the one used. Blank samples (field and laboratory) were weighed and analyzed with field samples for quality control. The concentration of total PM was calculated as the difference between the weights of the filters after and before sampling divided by the volume of air sampled. The results were corrected by the net values obtained from blank samples.
Culturable Bacteria
Bacterial samples were collected twice a week (sampling days were similar to those of total PM) using an SKC BioStage viable cascade impactor (SKC Inc., PA, USA) loaded with a tryptic soy agar (TSA) plate (DF0369176, BD Difco, Fisher Scientific, Ontario, Canada). Tryptic soy agar is a nonselective culture medium generally used for cultivation and isolation of fastidious and nonfastidious microorganisms (Sigma-Aldrich, 2018; Sansupa et al., 2021). Samples were collected for 30 s at a flow rate of 28 L min-1 using a QuickTake 30 sample pump (SKC Inc., PA, USA). The plates were then incubated at room conditions (temperature and relative humidity were approximately 23°C and 45%, respectively) for 16 h prior to counting the colony-forming units (CFU) of total culturable bacteria in each sample. Duplicate samples were collected in each room at 1 m above the birds and 1 m away from the exhaust, similar to PM samples. Bacterial concentrations were expressed as CFU m-3 of air sampled.
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Gases
Ammonia (NH3) and hydrogen sulfide (H2S) concentrations were monitored twice a week using Gastec diffusion tubes (Gastec Corporation, Kanagawa, Japan) with measuring ranges of 0.1-10 ppm and 2.5-1000 ppm for NH3 and 0.2-200 ppm for H2S. Samples were collected for 5 h. Carbon dioxide (CO2) was also monitored daily for 10 min using a handheld EXT-CO240 CO2 meter (accuracy: ±75ppm+5% of reading; Extech Instruments, New Hampshire, USA). Ozone (O3) concentrations were monitored through active sampling for 10 min using Gastec O3 detector tubes with a measuring range of 0.025-3 ppm and a hand-pump. This was to verify if O3 levels in the rooms were within the 8-h time-weighted average exposure limit of 100 ppb (OSHA, 2021), particularly in the treatment rooms where the EPI systems were installed. Similar to the abovementioned parameters, the sampling point for gases was 1 m above the birds and 1 m away from the exhaust.
Animal Productivity
The birds were weighed three times during the trial (i.e., Day 1, Day 17, and Day 34). All the birds were weighed in one group per room in all weighing events. Feed intake was recorded every time feeders were refilled, and feed conversion ratios (kilograms of feed per kilogram of weight gain) were calculated and corrected for mortality. Morbidity and mortality were monitored and recorded daily.
Data and Statistical Analyses
The efficacy of the EPI system was assessed by calculating the reduction efficiency (RE) for PM, bacteria, NH3, and H2S using equation 1.
(1)
where Cc and Ct are the average concentrations of PM, bacteria, NH3, and H2S in the control and treatment rooms, respectively. Control and treatment were compared in terms of the various parameters (PM, bacteria, gases, mortality, feed conversion ratio, and ventilation rate) using the Mann-Whitney test (R software, v. 4.0.2; The R Foundation for Statistical Computing Platform), a nonparametric test appropriate for small samples and observations (McKnight and Najab, 2010), as in this study. Differences between control and treatment with P values < 0.05 were considered statistically significant.
Results and Discussion
Ventilation Rates and Environmental Parameters
Figure 3 shows the average daytime ventilation rates in each room during the 35-day experiment (from 16 February to 22 March 2021). In the first few days of the experiment, when the birds were still young and the outside temperatures were low (daytime temperatures ranged from -6 °C to -22 °C in the first week), the ventilation rates did not go beyond the pre-set minimum ventilation rates (10% fan speed setting). The average ventilation rates between the control and treatment rooms were not significantly different (P > 0.05), even during the last few days of the experiment. The rates ranged from 185 to 855 m3 h-1 in the control rooms and from 187 to 966 m3 h-1 in the treatment rooms, corresponding to average ventilation rates of 0.23-1.24 m3 bird-1 h-1 in the control rooms and 0.23-1.34 m3 bird-1 h-1 in the treatment rooms. These values were within the recommended minimum ventilation rates for broiler housing (Seedorf et al., 1998; Aviagen, 2018).
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The average daily temperature and relative humidity were similar in all rooms. The average temperature on Day 1 was approximately 33°C (average ambient temperature was -22°C) and gradually decreased to approximately 20°C on Day 35 (average ambient temperature was 1°C) as the birds aged. The relative humidity varied from 33% to 65% over the trial period.
Particulate Matter
The concentrations of the various PM fractions in the treatment and control rooms increased as the broilers aged (fig. 4). The daily average concentrations in the control rooms ranged from 0.11 to 1.94 mg m-3 for PM1, 0.12 to 2.00 mg m-3 for PM2.5, 0.14 to 2.26 mg m-3 for PM4, 0.28 to 4.50 mg m-3 for PM10, and 0.46 to 7.62 mg m-3 for PM15 (fig. 4a). The concentrations of the different size fractions of PM were not significantly different (P > 0.05) between the control and treatment rooms in the first and last weeks of the experiment, during which the EPI units in the treatment rooms were not in operation, despite the difference (±33%) observed in figure 5. The similar PM levels in both control and treatment rooms during the first week indicate that the conditions in these rooms were similar, particularly in terms of PM concentrations. This is also supported by the similar trend in the diurnal variations in PM shown in figures 4a and 4b. For instance, the decrease in PM concentrations on Days 7 and 22 and the increase on Day 24 in the control rooms were also observed in the treatment rooms. The PM concentrations in the treatment and control rooms in the last week of the experiment (after the treatment) were generally similar, indicating that the treatment had no residual effects on particulate matter levels. However, when the EPI units were in operation (from the second to the fourth week of the experiment), the PM levels in the treatment rooms were significantly lower (P < 0.05) compared with those in the control rooms. The average concentrations in the treatment rooms during this period ranged from 0.11 to 1.19 mg m-3 for PM1, 0.12 to 1.22 mg m-3 for PM2.5, 0.14 to 1.37 mg m-3 for PM4, 0.28 to 2.67 mg m-3 for PM10, and 0.45 to 4.54 mg m-3 for PM15 (fig. 3b). These corresponded to average reductions of 50% for PM1, PM2.5, PM4, and PM15 and 49% for PM10 (fig. 5). The results show that reductions for the various size fractions of PM were not substantially different, indicating that the performance of the EPI system was similar for the different sizes of PM. Although this trend appeared to be contrary to what is theoretical, where larger particles tend to be removed easier than smaller particles, the results of this study are not uncommon, as they were also observed in the results of other studies (Manuzon et al., 2014; Zhao et al., 2018). Cambra-Lopez et al. (2009) obtained average reductions of 10% for PM2.5 and 36% for PM10 in experimental broiler houses in the Netherlands using a similar EPI system. Although the EPI system used in this study and the abovementioned related study were similar, the differences in the PM reductions obtained in these two studies could be due to several factors, such as differences in PM concentrations, environmental conditions, ventilation rates, collection surfaces, room size, and the configuration and installation of the EPI system. As shown in figure 5, when the EPI system was activated on Day 9, the reduction in the average PM concentrations in the treatment rooms relative to those in the control rooms increased unsteadily to a maximum of 64% for PM1, 63% for PM2.5 and PM4, 61% for PM10, and 62% for PM15 on Day 17, after which the reduction generally declined until the end of the experiment. Other studies (Cambra-Lopez et al., 2009; Tanaka and Zhang, 1996) also had similar observations. Cambra-Lopez et al. (2009) iterated possible causes of the decrease in PM reductions towards the end of the rearing cycle: (1) increase in PM concentration, (2) increase in ventilation rate, and (3) increase in PM layers on collection surfaces. Laboratory and modeling studies of an electrostatic precipitator treating PM emissions from poultry buildings have shown that PM removal efficiency decreases with increasing air velocity (or ventilation rate) (Manuzon and Zhao, 2009). The aforementioned studies found that operating at a velocity higher than 2 m s-1 led to re-entrainment of collected PM. Furthermore, Tanaka and Zhang (1996) pointed out that the PM layer can insulate the collection surfaces, resulting in a reduction of the electric field and, eventually, a reduction in the attraction of airborne PM to collecting surfaces. In this study, a slight increase in reduction was observed after cleaning the surfaces on Day 25; however, the values did not reach higher than 60%, as previously achieved. However, it should be noted that the surfaces were only partially cleaned.
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The average concentrations of total PM collected on PTFE filters in the control rooms ranged from 0.32 to 4.83 mg m-3 (average of 2.0 ±1.7 mg m-3) (fig. 6). This is relatively lower compared to the 9.56 ± 7.9 mg m-3 total PM levels observed by Kirychuk et al. (2006) in commercial floor-based poultry houses in the Canadian Prairies. The total PM concentrations in the treatment and control rooms were not significantly different (P > 0.05) during the first week of the experiment; however, when the EPI units were in operation from the second to the fourth week, the total PM concentrations in the treatment rooms were significantly reduced (P < 0.05); the concentrations ranged from 0.36 to 2.69 mg m-3. The average total PM reduction was approximately 40%; a maximum total PM reduction of 59% was obtained on Day 10, after which the PM reduction continued to decrease. A slight increase in reduction was observed on Day 29 after the surfaces were cleaned. However, on Day 32 (after the treatment), the average concentration in the treatment rooms was significantly higher (P > 0.05) than that in the control rooms, which could be due to the re-entrainment of collected particles into the air when the EPI system was turned off as there was no more attraction between the particles and the surfaces. The difference in the average reductions between total PM and PM fractions (total PM reduction was slightly lower than those of PM fractions) was probably due to the difference in the measurement methods used (gravimetric for total PM, whereas laser light-scattering photometry for PM fractions). Jerez et al. (2013) obtained a 39% total PM reduction in a commercial broiler facility in Texas using a similar EPI system. Ritz et al. (2006) also obtained an average of 43% total PM reduction in a commercial broiler house using an electrostatic space charge system.
Culturable Bacteria
The trends in the bacterial concentration in both treatment and control rooms appeared to be similar; they tended to be stable initially and then increased toward the end of the experiment (fig. 7). Other studies (Oppliger et al., 2008; CambraLopez et al., 2009; Jiang et al., 2018) also found increasing concentration of airborne bacteria over the rearing cycle. This seems reasonable because manure accumulation increases as the birds age (Mendes et al., 2012). The average total culturable bacterial concentrations in the treatment rooms during the second to fourth week ranged from 3.1×103 to 1.1×104 CFU m-3, which were significantly lower (P < 0.05) than those in the control rooms (8.0×103 to 1.5×104 CFU m-3). This corresponded to 27% to 62% reductions, with an average of 48%, over the three-week period. Bacterial concentrations were found to positively correlate with PM concentrations, probably because PM adsorbs and carries airborne bacteria. R2 values were 0.64 for control room total PM concentrations, 0.90 for treatment room total PM concentrations, 0.42-0.46 for control room PM fraction concentrations, and 0.92-0.93 for treatment room PM fraction concentrations. Airborne bacteria reductions of 76% (Richardson et al., 2003) and 67% (Mitchell et al., 2004) were obtained in broiler breeder houses using electrostatic space charge systems. Cambra-Lopez et al. (2009) did not find any significant effect of particle ionization on bacterial reduction.
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Gases
The NH3 concentrations in both treatment and control rooms increased over time (fig. 8). The values ranged from 1.6 to 7.5 ppm in the control rooms and 1.9 to 8.8 in the treatment rooms. Overall, the NH3 concentrations in both treatment and control rooms were not significantly different (P > 0.05). The highest reduction obtained was 31% (on Day 28; not shown in the graph). Using similar EPI systems, Cambra-Lopez et al. (2009) did not observe a significant reduction in NH3 in broiler houses; however, Jerez et al. (2013) observed a 17% reduction.
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No H2S was detected during the entire trial in both control and treatment rooms, indicating that the concentrations were below the detection limit of the tubes used (200 ppb). Jerez et al. (2013) measured up to 50 ppb of H2S in commercial broiler houses using a pulsed fluorescence SO2 detector. Similarly, no O3 was observed during the entire trial, indicating that the concentrations were below the detection limit of the tubes used (25 ppb). No O3 was also detected in other studies conducted in animal facilities, which used detector tubes with detection limits of 50 ppb (Manuzon et al., 2014) and 100 ppb (Cambra-Lopez et al., 2009).
Except for a few cases, CO2 concentrations in all rooms (fig. 9) were similar and within the 5000 ppm 8-h time-weighted average exposure limit (OSHA, 2022). The fluctuations in the concentrations were mainly due to the fluctuations in the ventilation rates (fig. 3). Carbon dioxide levels in animal buildings are an important indicator for ventilation rate and air quality.
Animal Performance
The average weight of the birds in both control and treatment rooms at the end of the experiment was 2.4 kg bird-1. This resulted in a feed conversion ratio of 1.4 kg feed kg-1 broiler for both control and treatment, which is lower compared to the 1.79 kg feed kg-1 broiler estimated by the National Chicken Council (NCC) in 2021 (NCC, 2022). It should be noted that lower feed conversion ratios indicate higher animal performance. In addition, the average mortality rates between the control (7.5±1.3%) and treatment (7.0±1.5%) rooms were not significantly different. The observed mortality rates were slightly higher than the 5.3% mortality rate estimated by the NCC in 2021 (NCC, 2022). The results of the feed conversion ratio and mortality indicate that although the EPI did not improve the birds’ performance, it did not have a detrimental effect on production. Other studies (Cambra-Lopez et al., 2009; Richardson et al., 2003; Ritz et al., 2006) also found no significant effects of the ionization on animal performance and mortality.
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Conclusions
An EPI system was evaluated on its performance in reducing PM, bacteria, NH3, and H2S in broiler houses for one growth cycle (35 days). Its impacts on animal performance and mortality were also assessed. On average, the EPI system reduced PM1, PM2.5, PM4, and PM15 by 50% and PM10 by 49%. The average reduction for total PM was 40% (0.32-4.83 mg m-3 in the control rooms and 0.36-2.69 mg m-3 in the treatment rooms). Total culturable bacteria was reduced by an average of 48%, and was found to positively correlate with PM concentrations. No significant reduction was observed for NH3. No H2S and O3 were detected during the entire study period. In addition, no significant effects were observed on feed conversion ratio and mortality in this experiment. Overall, the system showed potential in reducing PM and bacteria in broiler houses under current Canadian management systems and cold weather conditions. However, reductions in PM and bacteria decreased over time, which were possibly caused by increased concentration, ventilation rate, and dust layer on collection surfaces towards the end of the rearing cycle. Further assessments are required to determine if additional EPI units or collection surfaces could improve the performance of the system.
Acknowledgments
The authors acknowledge the financial support from the Saskatchewan Ministry of Agriculture through the Agriculture Development Fund (ADF) and Agriculture and Agri-Food Canada through Agrivita Canada Inc.
References
Aarnink, A. J., van Harn, J., van Hattum, T. G., Zhao, Y., & Ogink, N. W. (2011). Dust reduction in broiler houses by spraying rapeseed oil. Trans. ASABE, 54(4), 1479-1489. https://doi.org/10.13031/2013.39028
Air Movement and Control Association International Inc. (2016). Laboratory methods of testing fans for certified aerodynamic performance rating - ANSI/AMCA Standard 210-16 and ANSI/ASHRAE Standard 51-16. Retrieved from https://www.amca.org/assets/resources/public/pdf/Education%20Modules/AMCA%20210-16.pdf
Almuhanna, E. A., Maghirang, R. G., Murphy, J. P., & Erickson, L. E. (2009). Laboratory scale electrostatically assisted wet scrubber for controlling dust in livestock buildings. Appl. Eng. Agric., 25(5), 745-750. https://doi.org/10.13031/2013.28853
Alonso, C., Raynor, P. C., Davies, P. R., Morrison, R. B., & Torremorell, M. (2016). Evaluation of an electrostatic particle ionization technology for decreasing airborne pathogens in pigs. Aerobiologia, 32(3), 405-419. https://doi.org/10.1007/s10453-015-9413-3
Aviagen. (2018). Minimum ventilation rates for todays broiler. Retrieved from https://eu.aviagen.com/assets/Tech_Center/Broiler_Breeder_Tech_Articles/English/AviagenBrief-VentilationRates-2018-EN.pdf
Brauer, H., & Varma, Y. B. (2012). Air pollution control equipment. Heidelberg, Germany: Springer-Verlag.
Cambra-López, M., Winkel, A., van Harn, J., Ogink, N. W., & Aarnink, A. J. (2009). Ionization for reducing particulate matter emissions from poultry houses. Trans. ASABE, 52(5), 1757-1771. https://doi.org/10.13031/2013.29138
Caré, I., Bonthoux, F., & Fontaine, J.-R. (2014). Measurement of air flow in duct by velocity measurements. EPJ Web Conf., 77, 10. https://doi.org/10.1051/epjconf/20147700010
Chai, M., Lu, M., Keener, T., Khang, S.-J., Chaiwatpongsakorn, C., & Tisch, J. (2009). Using an improved electrostatic precipitator for poultry dust removal. J. Electrostat., 67(6), 870-875. https://doi.org/10.1016/j.elstat.2009.07.006
Elwinger, K., Fisher, C., Jeroch, H., Sauveur, B., Tiller, H., & Whitehead, C. C. (2016). A brief history of poultry nutrition over the last hundred years. World’s Poult. Sci. J., 72(4), 701-720. https://doi.org/10.1017/S004393391600074X
Gillespie, J., Nehring, R., & Hallahan, C. (2017). New versus old broiler housing technology: Which leads to greater profit? J. Appl. Poult. Res., 26(1), 72-83. https://doi.org/10.3382/japr/pfw047
Government of Ontario. (2022). Current occupational exposure limits for Ontario workplaces under Regulation 833. Retrieved from https://www.ontario.ca/page/current-occupational-exposure-limits-ontario-workplaces-under-regulation-833
Harmon, J. D., Hoff, S. J., & Rieck-Hinz, A. M. (2014). Animal housing - Electrostatic precipitation overview. Agriculture and Environment Extension Publications. Retrieved from http://lib.dr.iastate.edu/extension_ag_pubs/212
Jerez, S. B., Mukhtar, S., Faulkner, W., Casey, K. D., Borhan, M. S., & Smith, R. A. (2013). Evaluation of electrostatic particle ionization and biocurtain™ technologies to reduce air pollutants from broiler houses. Appl. Eng. Agric., 29(6), 975-984. https://doi.org/10.13031/aea.29.10011
Jiang, L., Zhang, J., Tang, J., Li, M., Zhao, X., Zhu, H.,... Zhang, X. (2018). Analyses of aerosol concentrations and bacterial community structures for closed cage broiler houses at different broiler growth stages in winter. J. Food Prot., 81(9), 1557-1564. https://doi.org/10.4315/0362-028X.JFP-17-524
Karcher, D. M., & Mench, J. A. (2018). 1 - Overview of commercial poultry production systems and their main welfare challenges. In J. A. Mench (Ed.), Advances in poultry welfare (pp. 3-25). Woodhead Publishing. https://doi.org/10.1016/B978-0-08-100915-4.00001-4
Kirychuk, S. P., Dosman, J. A., Reynolds, S. J., Willson, P., Senthilselvan, A., Feddes, J. J.,... Guenter, W. (2006). Total dust and endotoxin in poultry operations: Comparison between cage and floor housing and respiratory effects in workers. J. Occup. Environ. Med., 48(7), 741-748. https://doi.org/10.1097/01.jom.0000216215.39521.3c
Lee, M., Koziel, J. A., Macedo, N. R., Li, P., Chen, B., Jenks, W. S.,... Paris, R. V. (2021). Mitigation of particulate matter and airborne pathogens in swine barn emissions with filtration and UV-A photocatalysis. Catalysts, 11(11), 1302. https://doi.org/10.3390/catal11111302
Manuzon, R. B., & Zhao, L. (2009). Laboratory evaluation and modeling of electrostatic precipitation of PM emissions from poultry buildings. ASHRAE Trans., 115(2), 831-849.
Manuzon, R., Zhao, L., & Gecik, C. (2014). An optimized electrostatic precipitator for air cleaning of particulate emissions from poultry facilities. ASHRAE Trans., 120(1), 490-503.
McKnight, P. E., & Najab, J. (2010). Mann-Whitney U Test. In The Corsini Encyclopedia of Psychology (pp. 1-1). Hoboken, NJ: Wiley. https://doi.org/10.1002/9780470479216.corpsy0524
Mendes, L. B., Xin, H., & Li, H. (2012). Ammonia emissions of pullets and laying hens as affected by stocking density and manure accumulation time. Trans. ASABE, 55(3), 1067-1075. https://doi.org/10.13031/2013.41511
Mitchell, B. W., Richardson, L. J., Wilson, J. L., & Hofacre, C. L. (2004). Application of an electrostatic space charge system for dust, ammonia, and pathogen reduction in a broiler breeder house. Appl. Eng. Agric., 20(1), 87-93. https://doi.org/10.13031/2013.15686
National Chicken Council (NCC). (2022). U.S. broiler performance. Retrieved from https://www.nationalchickencouncil.org/about-the-industry/statistics/u-s-broiler-performance/
National Farm Animal Care Council. (2023). Code of practice for the care and handling of hatching eggs, breeders, chicken and turkeys. Retrieved from https://www.nfacc.ca/poultry-code-of-practice#section3
NIOSH. (2015). Particulates not otherwise regulated, total: Method 0501. In NIOSH Manual of Analytical Methods (NMAM) (5th ed.). National Institute for Occupational Safety and Health. Retrieved from https://www.cdc.gov/niosh/docs/2003-154/pdfs/0501.pdf
Nouri, H., Zouzou, N., Dascalescu, L., & Zebboudj, Y. (2016). Investigation of relative humidity effect on the particles velocity and collection efficiency of laboratory scale electrostatic precipitator. Process Saf. Environ. Prot., 104, A, 225-232. https://doi.org/10.1016/j.psep.2016.09.001
Oppliger, A., Charrière, N., Droz, P.-O., & Rinsoz, T. (2008). Exposure to bioaerosols in poultry houses at different stages of fattening; use of real-time PCR for airborne bacterial quantification. Ann. Occup. Hygiene, 52(5), 405-412. https://doi.org/10.1093/annhyg/men021
OSHA. (2021). Ozone. Occupational Safety and Health Administration. Retrieved from https://www.osha.gov/chemicaldata/9
OSHA. (2022). Carbon dioxide. Occupational Safety and Health Administration. Retrieved from https://www.osha.gov/chemicaldata/183
Richardson, L. J., Mitchell, B. W., Wilson, J. L., & Hofacre, C. L. (2003). Effect of an electrostatic space charge system on airborne dust and subsequent potential transmission of microorganisms to broiler breeder pullets by airborne dust. Avian Dis., 47(1), 128-133. https://doi.org/10.1637/0005-2086(2003)047[0128:EOAESC]2.0.CO;2
Rimac, D., Macan, J., Varnai, V. M., Vucemilo, M., Matkovic, K., Prester, L.,... Pavicic, I. (2010). Exposure to poultry dust and health effects in poultry workers: Impact of mould and mite allergens. Int. Arch. Occup. Environ. Health, 83(1), 9-19. https://doi.org/10.1007/s00420-009-0487-5
Ritz, C. W., Mitchell, B. W., Fairchild, B. D., Czarick, M., & Worley, J. W. (2006). Improving in-house air quality in broiler production facilities using an electrostatic space charge system. J. Appl. Poult. Res., 15(2), 333-340. https://doi.org/10.1093/japr/15.2.333
Ru, Y., Zhao, L., Hadlocon, L. J., Zhu, H., & Ramdon, S. K. (2017). Laboratory evaluation of electrostatic spray wet scrubber to control particulate matter emissions from poultry facilities. Environ. Technol., 38(1), 23-33. https://doi.org/10.1080/09593330.2016.1184319
Sansupa, C., Fareed Mohamed Wahdan, S., Disayathanoowat, T., & Purahong, W. (2021). Identifying hidden viable bacterial taxa in tropical forest soils using amplicon sequencing of enrichment cultures. Biology, 10(7), 569. https://doi.org/10.3390/biology10070569
Seedorf, J., Hartung, J., Schröder, M., Linkert, K. H., Pedersen, S., Takai, H.,... Wathes, C. M. (1998). A survey of ventilation rates in livestock buildings in northern Europe. J. Agric. Eng. Res., 70(1), 39-47. https://doi.org/10.1006/jaer.1997.0274
Sigma-Aldrich. (2018). 22091 Tryptic Soy Agar (Tryptone Soya Agar, Tsa, Caso Agar, Soybean Casein digest Agar). Retrieved from https://www.sigmaaldrich.com/deepweb/assets/sigmaaldrich/product/documents/122/065/22091dat.pdf
Tan, Z., & Zhang, Y. (2004). A review of effects and control methods of particulate matter in animal indoor environments. J. Air Waste Manag. Assoc., 54(7), 845-854. https://doi.org/10.1080/10473289.2004.10470950
Tanaka, A., & Zhang, Y. (1996). Dust settling efficiency and electrostatic effect of a negative ionization system. J. Agric. Saf. Health, 2(1), 39-47. https://doi.org/10.13031/2013.19440
Tavárez, M. A., & Solis de los Santos, F. (2016). Impact of genetics and breeding on broiler production performance: A look into the past, present, and future of the industry. Anim. Front., 6(4), 37-41. https://doi.org/10.2527/af.2016-0042
Viegas, S., Faísca, V. M., Dias, H., Clérigo, A., Carolino, E., & Viegas, C. (2013). Occupational exposure to poultry dust and effects on the respiratory system in workers. J. Toxicol. Environ. Health, Part A, 76(4-5), 230-239. https://doi.org/10.1080/15287394.2013.757199
Wenke, C., Pospiech, J., Reutter, T., Altmann, B., Truyen, U., & Speck, S. (2018). Impact of different supply air and recirculating air filtration systems on stable climate, animal health, and performance of fattening pigs in a commercial pig farm. PLoS One, 13(3), e0194641. https://doi.org/10.1371/journal.pone.0194641
Winkel, A., Mosquera, J., & Ogink, N. (2012). Removal efficiency of a wire-to-plate electrostatic precipitator for abatement of particulate matter emission from poultry houses. Proc. 2012 IX Int. Livestock Environment Symp. (ILES IX) (p. 3). St. Joseph, MI: ASABE. https://doi.org/10.13031/2013.41625
Winkel, A., Mosquera, J., Aarnink, A. J., Groot Koerkamp, P. W., & Ogink, N. W. (2016). Evaluation of oil spraying systems and air ionisation systems for abatement of particulate matter emission in commercial poultry houses. Biosyst. Eng., 150, 104-122. https://doi.org/10.1016/j.biosystemseng.2016.07.014
Zhao, Y., Chai, L., Richardson, B., & Xin, H. (2018). Field evaluation of an electrostatic air filtration system for reducing incoming particulate matter of a hen house. Trans. ASABE, 61(1), 295-304. https://doi.org/10.13031/trans.12533
Zheng, C., Wang, Y., Zhang, X., Yang, Z., Liu, S., Guo, Y.,... Gao, X. (2018). Current density distribution and optimization of the collection electrodes of a honeycomb wet electrostatic precipitator. RSC Adv., 8(54), 30701-30711. https://doi.org/10.1039/C8RA04765K