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A concrete slatted floor system that consists of a narrow-gap slatted floor and beneath it a slope bottom for separation of faeces and urine in pig houses was investigated. In the experiments, four concrete slatted floors with one of two slat profiles and one of two gap widths, and a steel wire slatted floor were studied to estimate their manure separation performance under practical conditions. To evaluate urine collection efficiency, seven slope gradients and two surface roughnesses of the slope bottom were investigated under laboratory conditions. The lowest percentage of faeces drainage (0.36%) and good urine drainage performance were obtained by a concrete slatted floor with 5 mm-wide gaps and a trapezoidal profile without sharp edges, indicating that separation of faeces and urine can be achieved on the surface of this slatted floor. Using the wet surface area of the slope bottom as an indicator of urine collection efficiency and emission source, a statistical model was developed based on slope gradient, surface roughness, amount of water and water drop height. It was found that the wet surface area of the slope bottom decreased as the slope gradient increased, but increased with increasing surface roughness. The wet surface area was much more sensitive to the variations of slope gradient at lower compared with higher gradient ranges.However, contrary sensitivity responses were obtained for surface roughness.A slope gradient of 201 with a surface coated with fine cement performed best and is recommended for the slope bottom design in the concrete slatted floor system.

The application of naturally ventilated pig buildings (NVPBs) with outdoor exercise yards is on the rise mainly due to animal welfare considerations, while the issue of emissions from the buildings to the surrounding environment is important. Since air pollutants are mainly transported by airflow, the knowledge on the airflow characteristics downwind the building is required. The objective of this research was to investigate airflow properties downwind of a NVPB with a roofed outdoor exercise yard for roof slopes of 5°, 15°, and 25°. Air velocities downwind a 1:50 scaled NVPB model were measured using a Laser Doppler Anemometer in a large boundary layer wind tunnel. A region with reduced mean air velocities was found along the downwind side of the building with a distance up to 0.5 m (i.e., 3.8 times building height), in which the emission concentration might be high. Additional air pollutant treatment technologies applied in this region might contribute to emission mitigation effectively. Furthermore, a wake zone with air recirculation was observed in this area. A smaller roof slope (i.e., 5° slope) resulted in a higher and shorter wake zone and thus a shorter air pollutant dispersion distance.

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