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Can Biochar Covers Reduce Emissions from Manure Lagoons While Capturing Nutrients?
Citation:
Dougherty, B., M. Gray, M. Johnson, AND M. Kleber. Can Biochar Covers Reduce Emissions from Manure Lagoons While Capturing Nutrients? JOURNAL OF ENVIRONMENTAL QUALITY. American Society of Agronomy, MADISON, WI, 46(3):659-666, (2017).
Impact/Purpose:
Odors and gasses emanating from animal manure lagoons poses an air quality problem. Additionally, release of nutrients from these lagoons poses an additional environmental risk. Biochar is a charcoal-like solid byproduct of bioenergy production. The unique physical and chemical properties of biochar makes it a promising material for odor, gas, and nutrient sorption. This study evaluated the potential of floating biochar covers to reduce odor and gas emissions while simultaneously capturing nutrients from liquid dairy manure. This new approach has the potential to mitigate multiple environmental problems. Two biochars were tested: one made via gasification of Douglas-fir chips, and the other made from a mixture of Douglas-fir bark and center wood. The mixed wood biochar reduced mean headspace ammonia (NH3) concentration by 72 to 80%, but no significant reduction was found with the wood chips alone biochar. Significant amounts of nutrients were sorbed by both biochars. In a separate sensory evaluation, reductions in mean odor offensiveness and mean odor threshold were observed in three of five biochar cover treatments compared to the control. These results show that biochar covers hold promise as an effective means for reducing odor and gas emissions while sorbing nutrients from liquid dairy manure, which in some areas, could mean a dramatic improvement in air quality and the environmental impacts of manure lagoons. This paper contributes to SHC 3.63.
Description:
The unique physical and chemical properties of biochars make them promising materials for odor, gas, and nutrient sorption. Floating covers made from organic materials (biocovers) are one option for reducing odor and gas emissions from livestock manure lagoons. This study evaluated the potential of floating biochar covers to reduce odor and gas emissions while simultaneously capturing nutrients from liquid dairy manure. This new approach has the potential to mitigate multiple environmental problems. Two biochars were tested: one made via gasification of Douglas-fir chips at 650°C (FC650), and the other made from a mixture of Douglas-fir bark and center wood pyrolyzed at 600°C (HF600). The HF600 biocover reduced mean headspace ammonia (NH3) concentration by 72 to 80%. No significant reduction was found with the FC650 biocover. Nutrient uptake ranged from 0.21 to 4.88 mg N g-1 biochar and 0.64 to 2.70 mg P g-1 biochar for the HF600 and FC650 biochars, respectively. Potassium ranged from a loss of 4.52 to a gain of 2.65 mg g-1 biochar for the FC650 and HF600 biochars, respectively. The biochars also sorbed Ca, Mg, Na, Fe, Al, and Si. In a separate sensory evaluation, judges assessed odor offensiveness and odor threshold of five biocover treatments including four biochars applied over dairy manure. Reductions in mean odor offensiveness and mean odor threshold were observed in three treatments compared to the control. These results show that biochar covers hold promise as an effective means for reducing odor and gas emissions while sorbing nutrients from liquid dairy manure.
