Laboratory evaluation of abatement measures for mitigating dust emission from cattle feedlots

Measures for mitigating dust emission from cattle feedlots were evaluated by using a laboratory chamber. The chamber, which has a cross section of 0.61 m × 0.61 m and a length of 3.7 m, has a layer of dry, loose, sieved feedlot manure above a compacted soil. The vertical movement of a cattle hoof was simulated by dropping a 4.5-kg steel weight onto the manure surface. High-volume samplers for PM ₁₀ (particulate matter smaller than 10-μm aerodynamic equivalent diameter) were used to collect suspended PM ₁₀. The applications of wheat straw, sawdust (242, 484, 726 g/m ²), and surface water (3.2 and 6.4 mm) on dust emission were investigated by using a 10-cm manure depth and 54-J drop energy of the steel weight. Results indicated that addition of wheat straw, sawdust, or water to the manure surface significantly decreased PM ₁₀ emission potential. The addition of magnesium chloride and an organic-based substance on the manure surface to control PM ₁₀ emission potential was also investigated and compared with surface water application; a manure depth of 10 cm, wet layer of 6.4 mm, and drop energy of 27 J were used. Surface applications of magnesium chloride and water did not result in any significant difference in PM ₁₀ emission potential. As the wet layer dried up, however, emission potential was significantly greater from the manure surface treated with magnesium chloride than from the water treatment. The manure treated with the organic-based substance had slightly greater emission potential immediately after application than did manure treated with magnesium chloride and water; but manure treated with the organic-based substance had the least emission potential during subsequent tests.