A concrete slatted floor system for separation of faeces and urine in pig houses

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 20° with a surface coated with fine cement performed best and is recommended for the slope bottom design in the concrete slatted floor system.