Development of an Environmentally Superior Treatment System for Replacing Anaerobic Swine Waste Lagoons

A full-scale treatment system for treatment of swine manure was developed to eliminate discharge to surface and ground waters and contamination of soil and groundwater by nutrients and heavy metals, along with related release of ammonia, odor, and pathogens. The system greatly increased the efficiency of liquid-solid separation by polymer injection to increase solids flocculation. Nitrogen management to reduce ammonia emissions was accomplished by passing the liquid through a module where bacteria transformed ammonia into harmless nitrogen gas. Subsequent alkaline treatment of the wastewater in a phosphorus module precipitated phosphorus and killed pathogens. Treated wastewater was recycled to clean hog houses and for crop irrigation. The system was tested during one year in a 4,400-head finishing farm as part of the Agreement between the Attorney General of North Carolina and Smithfield Foods/Premium Standard Farms to replace current anaerobic lagoons with environmentally superior technology. The system removed 97.6% of the suspended solids, 99.7% of BOD, 98.5% of TKN, 98.7% of ammonia, 95% of total P, 98.7% of copper and 99.0% of zinc. It also removed 97.9% of odor compounds in the liquid and reduced pathogen indicators to non-detectable levels. The existing anaerobic lagoon was transformed into an aerobic pond with low (< 30 mg/L) ammonia concentration. The treatment system was technically and operationally feasible. Based on performance obtained, it was determined that the treatment system met the Agreement’s technical performance standards that define an environmentally superior technology. This project was considered an important milestone in the search of alternative treatment technologies, and justified moving ahead with innovation and evaluation of lower cost, nextgeneration systems.