A proposed treatment train for sustainable energy and nutrient recovery from swine waste

Concentrated animal feeding operations (CAFOs) have become more prevalent due to increased meat demand; however, large amounts of manure are produced that must be treated and disposed of. Anaerobic lagoons and land application are common CAFO disposal methods, but possess significant environmental disadvantages and have increasingly limited use due to heightened regulations. A sustainable process for energy and nutrient recovery from swine waste was proposed and evaluated in this project that uses anaerobic digestion for bioenergy production and solids stabilization, followed by precipitation of struvite and recovery of N by ion exchange onto natural zeolites. Results from bench scale experiments show high recovery efficiencies of N and P (more than 80-90%) as valuable fertilizer; however, the quality of the effluent limits water reuse options. Life cycle assessment shows that the system provides significant environmental and human health benefits while a life cycle cost analysis shows significant economic benefits from recovery.