Biochar in the circular bionutrient economy

Area of Science:

• * Agricultural Science
• * Environmental Science
• * Material Science

Background:

• * The circular bionutrient economy focuses on nutrient cycling within managed organic residues.
• * Current nutrient management practices face challenges with nutrient loss and transportation costs.
• * Organic residues, including human excreta, contain valuable nutrients but require efficient recovery methods.

Purpose of the Study:

• * To explore biochar technology's potential to stimulate the circular bionutrient economy.
• * To identify key requirements for successful nutrient circularity using biochar.
• * To assess the economic and environmental implications of biochar-based nutrient recovery.

Main Methods:

• * Analysis of biochar's properties in capturing and processing nutrients from organic residues.
• * Evaluation of pyrolysis process impacts on waste reduction (weight and volume).
• * Calculation of potential nutrient contributions (e.g., nitrogen) from human excreta with and without urine incorporation.

Main Results:

• * Biochar facilitates dry nutrient capture, increasing market value and reducing transport costs.
• * Pyrolysis significantly reduces the weight (85-90%) and volume (74-90%) of excreta.
• * Including urine in nutrient recovery from human feces could increase nitrogen fertilizer contribution from 2% to 16-17% of global application.
• * Biochar enhances plant nutrient uptake through soil retention and pH buffering.

Conclusions:

• * Biochar technology offers a viable pathway to establish a circular bionutrient economy.
• * Public-private partnerships and marketable products are essential for incentivizing investment.
• * Internalizing environmental costs, potentially through carbon credits, may be necessary for cost-competitiveness with conventional fertilizers.