Biochar from Swine Manure: An Alternative for Nutrient Recovery and Slow-Release Fertilization

Area of Science:

• Agricultural Science
• Environmental Chemistry
• Materials Science

Background:

• Swine manure (SM) presents a significant waste management challenge.
• Nutrient recovery from SM is crucial for sustainable agriculture and reducing environmental pollution.
• Biochar production offers a method for waste valorization and nutrient sequestration.

Purpose of the Study:

• To optimize the production of swine manure biochar for enhanced nutrient recovery.
• To investigate the effects of different activation agents (KOH, HCl, MgCl2) and conditions on biochar properties.
• To evaluate the adsorption capacity of the optimized biochar for phosphate and ammonium.

Main Methods:

• Swine manure was activated with KOH, HCl, or MgCl2 at ratios of 1:1 and 3:1 (v/w).
• Activated materials were carbonized at temperatures of 400, 600, and 800 °C.
• Phosphate and ammonium adsorption capacities were determined using isotherm and kinetic studies.

Main Results:

• The optimal condition involved MgCl2 activation at 800 °C with a 3:1 ratio, yielding 84.9% biochar production.
• This biochar exhibited the highest phosphate (2.93 mg g⁻¹) and ammonium (1.27 mg g⁻¹) adsorption.
• Phosphate adsorption followed the Langmuir model (qm = 67.56 mg g⁻¹), and ammonium adsorption followed the Freundlich model (qm = 17.48 mg g⁻¹).
• Adsorption kinetics indicated chemisorption-controlled mechanisms for both nutrients.

Conclusions:

• MgCl2-activated swine manure biochar at 800 °C is highly effective for nutrient recovery.
• The biochar demonstrates potential as a slow-release fertilizer due to limited nutrient solubility.
• Optimized biochar production enhances sustainable nutrient management in agriculture.