Publications

Increased costs and reduced availability of common bedding materials have prompted Canadian dairy producers to search for alternatives such as recycled manure solids (RMS). Because of the perception that RMS have high bacterial counts, however, the dairy industry is skeptical about using RMS successfully, especially in a wetter, cooler area like Canada. At this point, it is hard for dairy producers to identify the best RMS production options. Therefore, the present study aimed to compare three solid-liquid manure separators (decanter centrifuge, roller press, and screw press) and four composting techniques (static or turned windrow and drum composter for 24 or 72 h) based on their performances and their impacts on RMS and air quality. In order to compare separators, the quantity of processed manure and the volume of the resulting solid fraction were measured, power consumption of separators was recorded, and samples of each constituent were collected for physical, chemical, and bacteriological analyses. When evaluating composting approaches, the RMS temperature and quality and the air quality (gas emissions and airborne microorganisms) were monitored, whereas 2 m3 of RMS per treatment were distributed into twelve independent bench-scale rooms in which was installed a polyethylene pipe to contain RMS during 10 d. The results suggested that Canadian dairy farmers should be oriented towards press separation and drum composting for 24 h to produce high-quality RMS. Presses are advantageous in terms of cost and RMS quality, and the use of a drum composter for 24 h allowed a maximum reduction of main bacterial species.