Evaluation of Physicochemical Separation Characteristics of Pig Manure According to the Type of Solid-Liquid Separator Processes

Abstract

This study evaluated various solid-liquid separation (SLS) processes used in pig farms for wastewater and livestock manure. SLS is crucial for recycling and purifying pig manure. Seven SLS processes were tested on 11 farms: centrifuge, centrifuge with coagulation agent, belt press with coagulation agent, drum screen, inclined screen, vibration screen, and screw press. Samples collected included raw manure, separated liquid, and solid manure after SLS processing, analyzed for pH, EC, moisture, CODMn, BOD5, TN, TP, K, TS, SS, NaCl, and heavy metals. Belt press with coagulation agent showed highest TS and SS reduction (78.8% and 96.9%). For TN and TP removal, belt press and centrifuge with coagulation agents achieved 41.0% and 94.2%, respectively. Belt press with coagulation agent removed 59.4% BOD5 and 66.0% CODMn. Centrifuge with coagulation agent removed 100% Zn and 98.6% Cu. Drum screen, inclined screen, vibration screen, screw press, and centrifuge without coagulation showed lower removal efficiency for nutrients, solids, Zn, and Cu compared to centrifugal and belt press with coagulation. Centrifugal and belt press with coagulation showed higher efficiency in removing nutrients, solids, and metals. Further studies are needed to understand its impact on linked biological or chemical processes.