Towards greenhouse gases mitigation for liquid pig slurry management with solid-liquid separation technologies

Area of Science:

• Environmental Science
• Agricultural Engineering
• Waste Management

Background:

• Solid-liquid separation (SLS) is crucial for managing animal slurry and reducing water pollution.
• A systematic analysis of centrifugation-based SLS with various flocculants and their impact on greenhouse gas (GHG) emissions is lacking.

Purpose of the Study:

• To investigate the effects of centrifugation with different flocculants on methane (CH4), nitrous oxide (N2O), and ammonia (NH3) emissions from pig slurry.
• To evaluate nitrogen (N) loss and CO2-equivalent (CO2-e) emissions from both liquid and solid fractions.

Main Methods:

• Screening of flocculants: polyferric sulfate (PFS), polyacrylamide (PAM), tannic acid (TA), and polyaluminum ferric chloride (PAFC).
• Monitoring of CH4, N2O, and NH3 emissions during storage of liquid fractions (3 months) and solid fractions (4 months).
• Evaluation of N loss and CO2-e emissions per kilogram of raw pig slurry.

Main Results:

• Standalone centrifugation increased GHG emissions by 23.7% compared to raw slurry.
• Flocculated centrifugation reduced GHG emissions by 17.7%-74.2% compared to centrifugation alone.
• Centrifugation with PFS and PAM showed significant GHG reductions (68.1% and 23.9%) compared to raw slurry, but N2O emissions from solid fraction storage remain a challenge.

Conclusions:

• Centrifugation-based SLS can mitigate CH4 but may not guarantee overall GHG reduction due to N2O emissions from solid fraction storage.
• Optimizing solid fraction storage is critical to suppress N2O emissions for effective long-term climate stabilization in pig slurry management.