Separation efficiency of different solid-liquid separation technologies for slurry and gas emissions of liquid and solid fractions: A meta-analysis

Solid-liquid separation (SLS) technology is widely used in the slurry management in animal farms. This study conducted a comprehensive meta-analysis of 45 published articles to evaluate the differences in separation efficiencies (SEX-SF) of various SLSs and the changes of gas emissions before and after the separation during on-farm slurry storage. The results indicated that the SEX-SF of the untreated raw slurry and acidified slurry were consistently greater than those of the digested slurry, and centrifugation resulted in greater SEX-SF than the other mechanical methods. Both measured and simulated data showed that the centrifuge technology had greater reductions in greenhouse gas (GHG) emissions relative to the screw press (56.1–58.0% vs. 38.9–40.2% for untreated slurry, and 29.7–30.2% vs. 22.5–23.2% for digested slurry), mainly due to CH4 reduction. Additionally, we identify the need for further assessment of the environmental risks that are associated with SLSs for the development of an optimal slurry management chain. [Display omitted] •Efficient solid–liquid phase separation depends on the separation technology.•Separation efficiency also depends on the slurry physicochemical properties.•Slurry storage increases ammonia, nitrous oxide, and carbon dioxide emissions.•Reduced methane emissions based on solid–liquid separation technology.•Solid–liquid separation technologies reduce GHG emissions during slurry storage.