Magnesium supplementation for improved struvite recovery from dairy lagoon wastewater

Recovery of phosphate (PO4-P) as struvite (MgNH4PO4·6H2O) from dairy lagoon wastewater (DW) limits contamination surface water arising application DW to crop fields. Magnesium (Mg) addition during PO4-P recovery is used promote precipitation and suppress formation undesired mineral products. A pilot-scale aerated fluidized-bed reactor was treat for recovery. The effect Mg concentration (0–20 mM) reaction pH (9–10) on mineralogy, thermal stability micronutrient content collected solids evaluated. Elemental analysis, scanning electron microscopy (SEM) with energy dispersive X-ray analysis (EDX), diffraction (XRD) Fourier transform infrared (FTIR) spectroscopy confirmed that the major NH4-N recovered (20–30% w/w). Simultaneous evolved gas (STA-EGA) showed ammonium (NH4-N) in had two maximums decomposition into ammonia (NH3(g)): low temperature (LT-NH3) at 100–109 °C, high (HT-NH3) 295–318 °C. Increasing did not improve reduced fraction HT-NH3 50% 14%. Higher concentrations also decreased sorption micronutrients such zinc iron solids. These observations indicate a potential benefit lower will increase reduce losses produced fertilizer.