Some research has been done to develop and assess the economic feasibility of more environmentally superior technologies. Five main alternatives which have been implemented in North Carolina are: a solids separation/nitrification–denitrification/soluble phosphorus removal system; a thermophilic anaerobic digester system; a centralized composting system; a gasification system; and a fluidized-bed combustion system. These systems were judged based on their ability to: reduce impacts of CAFO waste in the surface and groundwater, decrease ammonia emissions, decrease the escape of disease-transmitting pathogens, and lower the concentration of heavy metal contamination.