Project Description

2015-present

Human and animal exposure to hydrogen sulfide in animal barns has long been a severe issue due to its acute and chronic toxicity. Between 1975 and 2004, there are 14 fatal incidences during manure handling in Minnesota most possibly caused by exposure to elevated hydrogen sulfide level. The tolls in Minnesota rank the first among all states and are followed by Iowa. Hydrogen sulfide concentration in deep-pit swine barns is usually within hundreds of ppb; however, it can easily soar up to hundreds and even thousands of ppm during manure agitation and pumping operations. It has been known that anaerobic condition is created in liquid manure in storage so that sulfate-reducing bacteria convert sulfate to sulfide species over time. With the presence of sulfide species in liquid manure, it was conjectured that the quick rise is due to the release of gas originally trapped in manure slurry; however, there is no direct evidence and the detailed entrapment and release process remains unknown.

This study will evaluate hydrogen sulfide occurrence and transfer process during manure agitation of deep-pit storage. Manure will be sampled from foaming and non-foaming barns at different depth of the pit before and during manure agitation and pumping, and tested for the capability of hydrogen sulfide generation and gas bubble retention. Gas samples will also be collected at different sites of the barns. These samples will be analyzed for the spatial and temporal distributions of sulfide species. With this approach, the sulfide generation and transfer process due to agitation can be determined. The results will be important for controlling hydrogen sulfide during agitation and for reducing the risk of workers and animal death accidents, therefore, improving the agricultural safety and health in manure management systems.

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