Odor and Aeration Efficiency Affected by Solids in Swine Manure During Post-Aeration Storage

摘要

An extensive laboratory study followed by a limited field-scale investigation was carried out in this project with the goal of determining the relationship between manure solids levels and aeration times and rates as well as their effect on the length of odor-free storage after the combined separation and aeration treatment. In the laboratory study, three levels of aeration were examined (35 mV in oxidation-reduction potential [ORP], 1 and 3 mg L -1 in dissolved oxygen [DO]) in conjunction with three continuous aeration lengths (5, 15, and 30 days). All tests were performed on manure with solids levels of 0.5%, 1%, 2%, and 4% stored in PVC columns. The results showed that continuous aeration for 5, 15, and 30 days at 35 mV ORP, 1 and 3 mg L -1 DO levels was sufficient to keep the treated liquid odor-free for a storage period of up to 180 days if the manure solids levels were below 0.79%, 0.87%, and 0.96%; 0.82%, 1.0%, and 1.23%; and 1.02%, 1.11%, 1.52%, respectively. It turns out that in order to reduce aeration time and rates, the manure total solids content should not exceed 1%. The field experiment was conducted on a finishing farm located in Jackson County, Minnesota, where both solids-liquid separation and aeration were used by the producer in manure treatment. The site was composed of eight 600-head growing-finishing buildings equipped with shallow pits and a timer-controlled flushing system. With a 10 hp surface aerator, it would take about 83 and 74 days to reduce VFA and BOD to the respective levels, i.e., 230 and 171 mg L -1 , under which offensive odors are not supposed to be produced.