Animal Slurry Acidification Affects Particle Size Distribution and Improves Separation Efficiency.

Area of Science:

• Agricultural Science
• Environmental Engineering
• Chemical Engineering

Background:

• Solid-liquid separation is crucial for slurry management and reducing ammonia emissions.
• Slurry acidification is known to alter slurry characteristics, potentially impacting mechanical separation processes.

Purpose of the Study:

• To investigate the effects of slurry acidification on particle size distribution.
• To assess the impact of acidification on solid-liquid separation efficiency, particularly for phosphorus recovery.

Main Methods:

• Studied two slurry types (aged pig, fresh dairy) and two acidification additives (sulfuric acid, aluminum sulfate/alum).
• Analyzed particle size distribution and phosphorus (P) concentration in different fractions.
• Evaluated separation efficiency before and after acidification.

Main Results:

• Sulfuric acid increased phosphorus solubilization; alum did not.
• Acidification increased the solid fraction proportion, especially with alum.
• Alum significantly increased larger particle proportion (>100 μm) and P concentration within this range.
• Alum use markedly improved phosphorus separation efficiency, achieving ~90% removal in dairy slurry.

Conclusions:

• Slurry acidification significantly affects separation efficiency and particle size distribution.
• The choice of additive (e.g., alum) and slurry type are critical factors influencing these effects.
• Using alum before mechanical separation appears optimal for enhancing phosphorus content in the solid fraction.