(24c) Electrochemical Processing to Capture Phosphorus from Concentrated Animal Feeding Operations Waste: Experimental and Process Simulation Investigations
The development of phosphorus recycling technologies has recently become of interest, sparking a proliferation of scientific and technical research. Reducing phosphorus loss by increasing its recycling will increase phosphorus supply chain sustainability, food security, and watershed health. Recovery of nitrogen and phosphorus via struvite (MgNH4PO4·6H2O) precipitation is a recycling technique which can reduce watershed eutrophication and potentially increase fertilizer supply chain sustainability. Nucleation and growth of struvite crystals is controlled by solution pH which is dependent upon soluble magnesium, ammonia, and phosphorus specie concentrations.
Ohio University (OHIO) has been investigating a modular electrochemical-based technique to indirectly induce struvite precipitation within the liquid fraction of animal waste. Struvite precipitation was performed via chronoamperometry and struvite precipitates were characterized by scanning electron microscopy with energy-dispersive X-ray spectroscopy. Key parameters controlling electrochemical struvite precipitation include: solution pH, temperature, turbulence, and the presence of competing ions (Ca2+). Solution temperature greater than 20°C had negligible effects on struvite precipitation kinetics. The presence of Ca2+ was found to suppress phosphorus removal. The impact of operating voltage on phosphorus removal efficiency and current efficiency with time has also investigated. Further, process simulations have been developed to aid estimating operating costs for a commercial scale system integrated into a concentrated animal feeding operation (CAFO). This presentation will review recent laboratory and process simulation results.
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