ARS | Publication request: EVALUATION OF POLYMER SOLIDS SEPARATION, NITRIFICATION-DENITRIFICATION AND SOLUBLE PHOSPHORUS REMOVAL SYSTEM FOR TREATING SWINE MANURE

Submitted to: Proceedings of Intl Symposium Addressing Animal Production and Environment
Publication Type: Proceedings
Publication Acceptance Date: October 3, 2001
Publication Date: October 3, 2001

Technical Abstract: We evaluated an alternative system for treatment of liquid swine manure that does not require a lagoon. In this multistage system, solids and liquid are first separated with polyacrylamide (PAM) polymer, followed by biological N removal using high microbial density nitrification and denitrification and then P extraction through a lime precipitation process. .The pilot system was evaluated for 1 yr at the NCSU Lake Wheeler Rd. Field Laboratory using flushed swine manure from finishing and breeding houses. The average TKN concentration in the flushes was 555 mg/L with 64% in organic N forms and 36% as ammonia N. The total P averaged 245 mg/L with 88% organic P and 12% phosphate. Other characteristics of the liquid manure were: Total suspended solids = 5900 mg/L; Volatile suspended solids = 4800 mg/L; and BOD = 2600 mg/L. For solids separation, we used an in-line PAM injector and mixer to flocculate the solids in the flush and a sand filter bed for dewatering. PAM treatment reduced 85% of BOD, 98% of TSS and VSS, 60% of TKN, and 75% of TP. For N removal we used nitrifying bacteria entrapped in polymer pellets in aerated tank and denitrifying sludge in anoxic tanks that removed >90% of the ammonia N in the liquid after solids separation. Soluble P was effectively recovered as calcium phosphate (17% P2O5) after removal of ammonia and carbonate buffers during nitrification and precipitation with Ca(OH)2. Pathogens (i.e., salmonellae, enterococci) were reduced at least 4 logs. Overall, our results indicate that systems without lagoons are technically feasible. A full-scale system will be demonstrated using resources from the Smithfield Foods/PSF & NC Attorney General Agreement for verification of Environmental Superior Technology.