REMOVAL OF SOLIDS AND MAJOR PLANT NUTRIENTS FROM SWINE MANURE USING A SCREW PRESS SEPARATOR

Abstract

A screw press separator was temporarily installed on a commercial swine farm in Horry County, South Carolina.The separator had a 0.5 mm screen and was operated with a single 40 kg weight on each pressure plate arm. Predictionequations were developed from the data to describe the removal of total solids (TS), total volatile solids (VS), chemical oxygendemand (COD), total Kjeldahl nitrogen (TKN), ammonium nitrogen (NH4 N), organic nitrogen (organicN), and totalphosphorus (TP). Separated solids were analyzed to determine the percent total solids and the concentration of major plantnutrients. The concentration of total potassium (TK) in the separator influent and effluent was the same within measurementerror. The removal of TS, VS, N, and P was found to vary significantly with the TS concentration of the influent manure.Therefore, building management and the methods used to implement the machine in the manure handling system would havea significant impact on separator performance. The prediction equations were used to calculate separator performance fora typical pitrecharge swine building based on observed characteristics on the cooperators farm. The screw press would becapable of removing 14.9% of the TS, 19.6% of the VS, 34.9% of the COD, 9.2% of the TKN, 16.0% of the organicN, and14.8% of the TP from the manure added by housed swine.