FLOCCULATION OF SWINE MANURE: INFLUENCE OF FLOCCULANT, RATE OF ADDITION, AND DIET

Abstract

Manure was collected from growing pigs (22 to 48 kg) fed one of 11 diets varying in total and nonphytatephosphorus content during each of three feeding periods. Reduced phosphorus diets were amended with feed additivesintended to improve availability of phytate phosphorus. Five flocculants plus a control were added at each of threeconcentrations, and the diluted mixtures (0.24% TS) were allowed to settle for two 10min settling periods. Volume of settledmaterial was recorded following each settling period. After 20min settling time, TS content of settled material andP concentration of the effluent were determined. Results indicated that Al2(SO4)3 and FeCl3 were the most effectiveflocculants. Little improvement was observed when the flocculant was added at a concentration of 625 mg flocculant/Lcompared to 250 mg flocculant/L. Both flocculants recovered over 85% of solids and over 70% of the phosphorus. Additionof Al2(SO4)3 at a concentration of 625 mg/L increased phosphorus removal to 90%. Diet, feeding period, and the interactionof diet and feeding period were significant influences on solids settling, solids settled after 10min settling time comparedto 20 min, and phosphorus settling. Inclusion of dietary additives did not clearly influence results. Prediction equations weredeveloped to estimate solids and phosphorus removals for each flocculant tested.