Efficiency and Gas Emission Assessment of Various Solid-liquid Separation Technologies for Animal Slurry: A Meta Analysis

Solid-liquid separation technology is widely used in animal farms to manage slurry. To evaluate the distribution of components in slurry under the application of different solid-liquid separation technologies, 36 published articles were screened for comprehensive meta-analysis. The results of data analysis show that the separation efficiency (E_X-SF) of slurry was positively correlated with dry matter content of raw slurry. Centrifuge and screw press are the two most widely used separation technologies in practical production. With the same dry matter content of raw slurry, the E_X-SF of centrifuge is higher than that of screw press. The efficiencies of different separation technologies are classified according to the removal efficiency and separation efficiency. The E_X-SF of FM, DM, VS, TN, TAN, TP and TK in solids of the high efficiency group are 2.5, 1.9, 1.6, 3.1, 5.2, 2.3 and 3.1 times as high as that of the low efficiency group, respectively. After solid-liquid separation, the CH₄ and GHG emissions of the slurry were significantly reduced by 34.4%-67.9% and 38.9%-60.7%, respectively. The high efficiency group has higher potential of gas emission reduction than the low efficiency group. This study also provides theoretical basis for the prediction of the efficiency and environmental impact of different liquid and solid components separation technologies in storage and field application, which has important reference value for the accurate evaluation and safe utilization of separated slurry in China.