Enhanced copper passivation in pig manure composting through iron nanoparticle amendment

Area of Science:

• Environmental Science
• Nanotechnology
• Agricultural Science

Background:

• China's large pig production leads to significant agricultural pollution from untreated pig manure.
• Passivating metal toxicity in pig manure is a critical environmental challenge.

Purpose of the Study:

• To investigate the effect of green synthesized iron nanoparticles (G-nFe) on copper (Cu) transformations during thermophilic aerobic composting of pig manure.

Main Methods:

• Addition of G-nFe to pig manure during thermophilic aerobic composting.
• Analysis of Cu fractions (EXC-Cu, CARCu, IMOCu, OM-Cu, RESCu) using various analytical techniques.
• Characterization of organic matter (OM) and humus, and Fourier transform infrared (FTIR) analysis.

Main Results:

• G-nFe addition significantly increased passivation of active Cu forms (EXC-Cu, CARCu, IMOCu).
• The fraction of organic matter-bound Cu (OM-Cu) increased, particularly with a G-nFe dose of 500 mL kg⁻¹.
• G-nFe exhibited dual effects on residual Cu (RESCu), initially increasing then significantly reducing it over the composting process.

Conclusions:

• G-nFe addition effectively promotes the transformation of Cu into stable OM-Cu fractions.
• Iron nanomaterials can enhance metal ion passivation during composting, offering a viable solution for agricultural waste management.