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Lehmann Lab

Section of Soil and Crop Sciences

Nutrient recycling: from waste to value

Nutrients are increasingly removed from agricultural fields to wastes, breaking nutrient cycles that were once closed. This can have severe consequences for environmental pollution of for example drinking water. Recycling agricultural wastes and feces will be important to move us towards a circular economy to both reduce pollution as well as secure future nutrient supply for agriculture. Our group has examined pyrolysis to produce fertilizers from slaughterhouse wastes and animal as well as human feces.

 

Recent insights include:

Pyrolysis increases plant-availability of waste nutrients while decreasing water solubility that may reduce unproductive losses.

Large amounts of phosphate could be recycled from wastes: if we utilize the phosphate in discarded slaughterhouse wastes in Ethiopia, we could offset more than half its current phosphate fertilizer imports.

Carbon dioxide priming of feces biochar increases its ability to capture ammonia in order to recycle nitrogen from liquid wastes.

Featured recent publication: Krounbi L, Enders A, Anderton CR, Engelhard MH, Hestrin R, Torres-Rojas D, Dynes JJ, and Lehmann J 2020 Sequential ammonia and carbon dioxide adsorption on pyrolyzed biomass to recover waste stream nutrients. ACS Sustainable Chemistry & Engineering 8, 7121-7131. (supporting online material)

 

In the next few years, we will mainly focus on the following questions:

What are the global amounts of nutrients that can be recycled as agricultural fertilizers from human feces and urine?

How can nutrients be recycled from urban to rural ecosystems?

How can we improve fertilizer value of poultry and dairy manures?

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