Electrochemical Processing to Capture Phosphorus from Simulated Concentrated Animal Feeding Operations Waste

Abstract

The primary objective of this study is to evaluate an electrochemical-based approach to selectively recover P and N from simulated animal waste as a solid struvite (MgNH4PO4·6H2O) product, which can be reused as a slow release fertilizer. The effect of applied potential, flow turbulence, waste composition, and temperature on struvite precipitation kinetics was investigated. 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+). It was found increasing hydrodynamic flow up to 600 rpm resulted in faster transport of dissolved oxygen to the electrode interface, controlling the struvite precipitation rate. Solution temperature greater than 20°C had negligible effects on struvite precipitation kinetics. The presence of Ca2+ was found to suppress phosphorus removal.