Development of an innovative in-barn manure handling system for grower-finisher pigs to separate feces from urine: assessment of impact on odor and gaseous emissions

Abstract

In this work, a new housing system for grower-finisher pigs that incorporates a belt conveyor (BC) system to separate feces from the urine at the pen level was developed. This innovative manure handling system was evaluated for its effectiveness in partitioning nutrients (i.e., phosphorus and nitrogen) in the separated solid and liquid manure components as well as its impact on pig well-being, and on odor and gaseous emissions. Experiments conducted at two collaborating research facilities allowed for the comparative evaluation of two small-scale rooms one that simulated a conventional swine production room with partially slatted floor pen and a shallow pit and a second room that featured the new pen design concept with the BC replacing the concrete pen floor slats. Four trials were completed at each facility. Results of the trials showed that the performance and well-being of the animals were not adversely affected by the use of the BC pen design. The BC system was effective in isolating most of the phosphorus in a low mass solid phase; 76 to 81% of the phosphorus excreted by the pigs in the BC room was isolated within the solid phase of excreta representing 20% of the total manure mass. Various opportunities exist to refine the BC pen concept to reduce the total water usage and consequently, to reduce the total manure production as well. The overall trends in gas concentration levels (i.e., NH3 and CO2) observed in trials conducted at the two locations indicated that the BC pen design contributed to the reduction in the levels of these gases. The odor concentration values for the samples taken from the conventional and BC rooms were highly variable, thus statistical comparison of the odor values from the two chambers showed no significant difference (p>0.05). The overall trends in gas emission rates showed that the BC pen design concept can help reduce the emission rate of carbon dioxide compared to the conventional room. No significant impact of the system was observed for ammonia and odor emissions. Further work to better assess the technology is recommended, particularly with respect to improved control of inlet air contaminant levels and more accurate assessment of odor and hydrogen sulfide concentrations.