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ARS Home » Southeast Area » Florence, South Carolina » Coastal Plain Soil, Water and Plant Conservation Research » Research » Publications at this Location » Publication #342612

Research Project: Improvement of Soil Management Practices and Manure Treatment/Handling Systems of the Southern Coastal Plain

Location: Coastal Plain Soil, Water and Plant Conservation Research

Title: Hydrothermal carbonization of food waste for nutrient recovery and resuse

Author
item Idowu, Ifeolu - University Of South Carolina
item Liang, Li - University Of South Carolina
item Flora, Joseph - University Of South Carolina
item Pellechia, Perry - University Of South Carolina
item Darko, Samuel - Benedict College
item Ro, Kyoung
item Berge, Nicole - University Of South Carolina

Submitted to: Waste Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/31/2017
Publication Date: 9/6/2017
Citation: Idowu, I., Liang, L., Flora, J., Pellechia, P.J., Darko, S.A., Ro, K.S., Berge, N.D. 2017. Hydrothermal carbonization of food waste for nutrient recovery and resuse. Waste Management. http://www.sciencedirect.com/science/article/pii/S0956053X17306293.

Interpretive Summary: Hydrothermal carbonization (HTC) is an emerging technology to convert wet organic wastes into carbonaceous solid product called hydrochar under relatively low water temperature and high pressure. This study investigates the effects of HTC reaction temperature and time on the fate of nutrients in the food wastes collected from restaurants. Results from this work indicate that at all evaluated reaction times and temperatures, the majority of nitrogen, calcium, and magnesium remain integrated within the hydrochar, while the majority of potassium and sodium reside in the process water. The fate of phosphorus is dependent on reaction times and temperatures, with hydrochar integration increasing with higher reaction temperature and longer time. A series of leaching experiments to determine potential hydrochar nutrient availability indicate that, at least in the short term, nitrogen release from the solids is small, while almost all of the phosphorus present in the solids produced from carbonizing at 225 and 250 degree Celsius (oC) is released. At a reaction temperature of 275 oC, smaller fractions of the total phosphorus in the hydrochar are released as reaction times increase. It is estimated that up to 0.96% and 2.30% of nitrogen and phosphorus-based fertilizers, respectively, in the US can be replaced by the nutrients integrated within the hydrochar and process water generated from hydrothermal carbonization of currently landfilled food wastes.

Technical Abstract: Food waste represents a rather large and currently underutilized source of potentially available and reusable nutrients. Laboratory-scale experiments evaluating the hydrothermal carbonization of food wastes collected from restaurants were conducted to understand how changes in feedstock composition and carbonization process conditions influence primary and secondary nutrient fate. Results from this work indicate that at all evaluated reaction times and temperatures, the majority of nitrogen, calcium, and magnesium remain integrated within the solid-phase, while the majority of potassium and sodium reside in the liquid-phase. The fate of phosphorus is dependent on reaction times and temperatures, with solid-phase integration increasing with higher reaction temperature and longer time. A series of leaching experiments to determine potential solid-phase nutrient availability were also conducted and indicate that, at least in the short term, nitrogen release from the solids is small, while almost all of the phosphorus present in the solids produced from carbonizing at 225 and 250 degree Celsius (oC) is released. At a reaction temperature of 275 oC, smaller fractions of the solid-phase total phosphorus are released as reaction times increase, likely due to increased solids incorporation. Using these data, it is estimated that up to 0.96% and 2.30% of nitrogen and phosphorus-based fertilizers, respectively, in the US can be replaced by the nutrients integrated within hydrochar and liquid-phases generated from the carbonization of currently landfilled food wastes.