Test results in a hog finishing barn demonstrate that the Electrostatic Space Discharge System (ESDS) maintained a significant level of dust reduction compared to the control group.
The ESDS reduced 63% of total particle sizes (expressed as “total spatial particulates” or TSP) of dust and 47% of smaller particles less than 10 microns in size (PM-10). The 10-micron and smaller dust particles are the size inhaled by workers in hog barns.
Dust is a mixture of very small particles and liquid droplets that can cause or worsen health conditions in people and pigs. The PM-10 and smaller particles are of most concern because they can settle in the bronchia and lungs.
The ESDS reduces dust by negatively charging particles and causing them to attach to walls and equipment in the barn. This reduces the dust concentration in the room air as well as the air exhausted through the ventilation fans.
The ESDS has been shown to reduce dust levels in poultry buildings with great success — but little is known about the advantages in swine confinement facilities, the main goal of this research project.
To evaluate ESDS, a 1,000-head, two-room finishing barn was tested. Each room contained 24 pens, 12 per side. One room was equipped with an ESDS unit and the other served as a control.
The ventilation in each room included four pit fans and six wall fans. The ventilation controller was set to run through six stages. Fresh air entered the room through quad ceiling inlets for stages 1-3, and entered through wall inlets near the ceiling during stages 4-6.
Ventilation air flow ranged from 8 to 22% less than fan manufacturers' published data, probably due to the dirtiness of the fans.
The ESDS consists of an electrical multiple wire design, which maximizes the ions created by the 30,000 volts in the ESDS.
Air samples in each room were collected using MiniVol portable air samplers suspended 6 ft. above the slotted floor. The system samples air at 1.3 gal./minute, collecting in three different particulate categories: total spatial particulates (TSP), particles less than 10 microns (PM-10) and particles under 2.5 microns (PM-2.5). Particle size separation is achieved through impaction and collection on 2-in. filters.
Dust samples were collected over 24-hour periods. The collection process was repeated three times at about six-week intervals: first for 29- to 48-lb. pigs, then for 150- to 169-lb. pigs and finally for 240- to 260-lb. pigs. Each filter was weighed before and after sampling to get the mass of the dust particles on the filter.
The greatest amount of TSP removal occurred in all three finisher weight groups (Figure 3 ).
Also, the first group of finishing pigs weighing 29-48 lb. showed a greater percentage reduction of dust particles.
Concentrations of dust removed were less in general for the middle weight group (150-169 lb.) because outside temperatures were warmer, increasing fan operation and decreasing dust concentration because of greater air exchange.
The application of the ESDS technology needs further study to determine the impact on other hog barn issues, such as odor, pathogens and gases, researchers note.
Dust will continue to be an issue in swine barns. Efficient and effective ways of removal will be key to maintaining a healthy working environment for the workers and for swine.
Researchers: R.E. Nicolai and B.J. Hofer, both of South Dakota State University. Contact Nicolai by phone (605) 688-5663, fax (605) 688-6764 or e-mail [email protected] .