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ARS Home » Midwest Area » St. Paul, Minnesota » Soil and Water Management Research » Research » Publications at this Location » Publication #306021
Title: Phosphorus reclamation through hydrothermal carbonization of animal manures

Author
item HEILMANN, STEVEN - University Of Minnesota
item MOLDE, JOSEPH - University Of Minnesota
item TIMLER, JACOBE - University Of Minnesota
item WOOD, BRANDON - University Of Minnesota
item MIKULA, ANTHONY L - University Of Minnesota
item VOZHDAYEV, GEORGIY - University Of Minnesota
item Spokas, Kurt
item COLOSKY, EDWARD - University Of Minnesota
item VALENTAS, KENNETH - University Of Minnesota

Submitted to: Journal of Environmental Science and Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/11/2014
Publication Date: 8/11/2014
Publication URL: http://handle.nal.usda.gov/10113/59572
Citation: Heilmann, S.M., Molde, J.S., Timler, J.G., Wood, B.M., Mikula, A., Vozhdayev, G.V., Spokas, K.A., Colosky, E., Valentas, K.J. 2014. Phosphorus reclamation through hydrothermal carbonization of animal manures. Journal of Environmental Science and Technology. 48(17):10323-10329.

Interpretive Summary: Society currently depends on mining of phosphorus as our source of this critical nutrient. Projected shortages of global phosphate have prompted research into various means of recycling phosphorus in various forms. Hydrothermal carbonization of animal manures from large corporate farms was investigated as a way to recycle phosphorus for agricultural use and to mitigate the negative environmental impact of phosphate pollution. We examined various agricultural manure types (e.g., poultry, swine, and cattle manures) as possible sources for this process. Overall, we did recovery a majority of phosphorus in the solid product of the hydrothermal process. We achieved yields in the range of 81-87% based on starting manures. Also, swine and cattle manures produced hydrochars with energy contents comparable to coal. Additional research is needed to fully characterize the chemistry, but this method does hold promise. These results are significant to farmers and policy makers and will assist scientists and engineers in developing improved methods to recycle phosphorus for agricultural use.

Technical Abstract: Projected shortages of global phosphate have prompted investigation of methods that could be employed to capture and recycle phosphate, rather than continue to allow the resource to be essentially irreversibly lost through dilution in surface waters. Hydrothermal carbonization of animal manures from large corporate farms was investigated as a scenario for reclamation of phosphorus for agricultural use and to mitigate the negative environmental impact of phosphate pollution. Hydrothermal reaction conditions were identified for poultry, swine, and cattle manures that resulted in hydrochar yields of 50 – 60% for all three manures, and > 90% of the total phosphorus present in these systems was contained in the hydrochars as precipitated phosphate salts. Phosphorus recovery, principally as calcium phosphate, was achieved in yields of 80 - 90% by subsequent acid treatment of the hydrochars, addition of base to acid extracts to achieve pH 9, and filtration. Overall reclamation yields of phosphate achieved were in the range of 81-87% based on starting manures. Swine and cattle manures produced hydrochars with combustion energy contents comparable to high end sub-bituminous coals.