Submitted to: Technical Conference on Water Quality Proceedings of Solutions
Publication Type: Proceedings
Publication Acceptance Date: April 15, 1996
Publication Date: N/A
Interpretive Summary: Swine production systems of the future should conserve the maximum amount of nutrients that land can assimilate without causing overapplication and pollution. Assigning nutrients to nutrient deficient areas through solids separation and transport appears critical to overcome current land limitations associated with huge confined swine operations in the Southeast region. Separation of suspended solids from diluted wastewaters is difficult and requires some type of chemical coagulation to bind together the small particles of solids in the water into larger clumps. Treatment with 10 ppm of cationic polyacryamide polymer reduced 33% of the suspended solids contained in a swine effluent. Also critical is the removal of excess nitrogen. Nitrification is a very limiting process in animal waste treatment, but a necessary condition to be able to remove nitrogen from the farm in the form of N2. We are investigating the use of microorganisms immobilized in polymer resins to improve nitrogen removal from swine wastewater.
Technical Abstract: Confined livestock production is one of the fastest growing industries in the southeastern United States. As a consequence, many counties already are producing more manure nitrogen than available land can absorb, causing water pollution problems. We describe two technologies used in municipal wastewater treatment plants, and we evaluate their applicability to treat swine wastewater. The first technology uses polyacrylamide (PAM) flocculants to remove nutrients and solids from diluted swine wastewaters typical of flushing systems. Our evaluation of PAM polymers showed that this treatment is very effective and better than alum for separating solids and nutrients from the wastewater stream. Application of 10 ppm of cationic PAM reduced 33% of the suspended solids, 38% of COD, and 82% of the organic nitrogen. The second technology uses microorganisms encapsulated in polyethylene glycol (PEG) polymer pellets for nitrification enhancement. The rate of nitrification with PEG pellets is about 250 mg of ammonia-N per L per day at a 7.5% pellet to total volume ratio, or three times higher than that of conventional activated sludge processes. This higher nitrification efficiency results in shorter retention times and aeration cost savings. Our measurement of oxygen demand in lagoon effluents in North Carolina farms showed a BOD5 of 97.4 ñ 0.7 and a carbonaceous BOD of 46.4 ñ 2.2. This means that waste stabilization conditions are adequate to use PEG technology.