Degree Type


Date of Award


Degree Name

Master of Science


Agricultural and Biosystems Engineering


Agricultural and Biosystems Engineering

First Advisor

Jacek A. Koziel


The swine industry is facing challenges due to emissions of odorous and potentially harmful gases from stored manure. Volatile organic compounds (VOCs), hydrogen sulfide (H2S), and ammonia (NH3) are odorous and can be dangerous to humans and animals at high concentrations. Greenhouse gases (GHG) are linked to climate change. Scientists and engineers have been working on developing technologies to solve this issue. Manure additives are one of the methods used by the livestock industry to control emissions. Manure additives are relatively inexpensive, user-friendly for the farmers, and, most importantly, can be implemented without changing the current manure storage structure. However, little scientific data exists to show the performance of marketed products. Thus, the objective of this research was to test the performance of marketed pit manure additives in mitigating gaseous emissions. Eight commercial manure additive products were evaluated on their effectiveness in mitigating odor, NH3, H2S, GHG, and VOC emissions in a pilot-scale setup. A manure storage simulator was used with a maximum storage capacity of 138 L and a controlled headspace to match pit ventilation conditions on a barn-scale. The comprehensive summary of the performance of eight products to mitigate gaseous emissions was reported. No significant reduction of any target gas emissions was measured for all eight additives.

An additional preliminary experiment was conducted to determine whether biochar could mitigate the instantaneous release of H2S and NH3 from swine manure during agitation (a common practice before manure is pumped out). Preliminary data analyses show that a 0.25” thick layer treatment of biochar on the top manure surface in the storage simulator resulted in a 59% reduction in total emission of NH3 and a 62% reduction in H2S emissions during the 3 min agitation. The 0.5” biochar layer treatment resulted in a 52% reduction in NH3 total emission and a 57% reduction in H2S emissions during the 3 min agitation. From the time of starting agitation until the concentrations of both gases reset back to before agitation, the 0.25” biochar layer had a 91% reduction in total emission of NH3 and a 90% reduction in H2S total emission, while the 0.5” biochar layer had a 59% reduction in total emissions of NH3 and a 41% reduction in H2S emission, respectively. Overall the 0.25” biochar layer results in a better reduction than 0.5” biochar layer. The application of biochar prior to the pump-out of manure appears to be a viable solution to lower the risk of excessively high concentrations of H2S and NH3. Further research is warranted to test this idea in a full-scale.

Copyright Owner

Baitong Chen



File Format


File Size

68 pages