An aerated fluidized bed reactor (aerated-FBR) was used for recovery of orthophosphate (PO 4 −P) from dairy wastewater (D-WW) and swine wastewater (S-WW) by struvite (MgNH 4 PO 4 •6H 2 O) precipitation. Model wastewater solutions (S-model, D-model) free of organic material were also treated. The maximum PO 4 −P recovery for treated livestock wastes was 94% for S-WW and 63% for D-WW. The PO 4 −P recovery did not improve for S-model compared to S-WW, but increased to 81% for D-model relative to D-WW, suggesting that the high organic content of D-WW may hinder the recovery process. X-ray diffraction (XRD) analysis of recovered solids revealed that treated S-WW produced mostly struvite (95−98%) while D-WW yielded a mixture of struvite (28−33%), calcite (CaCO 3 ; 17−55%), and monohydrocalcite (CaCO 3 •H 2 O; 13−42%). The Fourier transform infrared (FTIR) spectra of the solids confirm the presence of vibrational bands associated with these minerals. Simultaneous thermal analysis (STA) indicated that all solids, except for D-WW, show thermogravimetric (TG) trends consistent with the struvite and calcium carbonate content. The D-WW solids had additional TG steps, possibly due to high organic and colloidal content, and slightly improved ammonium stability. The aerated-FBR treatment is an effective method to reduce PO 4 −P from livestock wastewater through precipitation of pure struvite and struvite/calcium carbonate mixtures.

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Struvite (MgNH4PO4·6H2O) can be recovered from wastewaters for mitigation of phosphorus content. However, the interaction of dissolved constituents with struvite is rarely evaluated. Removal of heavy metals and total organic carbon (TOC) in a greenhouse wastewater (GW) by struvite was investigated. Presynthesized struvite was added to GW and removal of Zn (689 μg/L), Cu (151 μg/L), and TOC (51 mg/L) monitored from 1 to 26 d. Metal uptake in sodium nitrate solutions was used to assess competition, and the influence of other GW constituents on sorption. Struvite was also directly precipitated from GW (PPT). Recovered GW solids had 64–247 mg/kg Zn, 12–54 mg/kg Cu, and 1721–8806 mg/kg TOC, with lowest loadings for PPT and highest for 26 d solids. X-ray absorption spectroscopy detected polymerized Zn-phosphate, induced by dissolved phosphorus in GW, and Cu copolymerization, initially limited by aqueous Cu-organic complexation. Sorbed Cu shifts Fourier transform infrared-sensitive phosphate bands and changes the intensities of reflections in X-ray diffraction patterns of struvite more so than Zn. Struvite from GW is more susceptible to thermal decomposition than unreacted struvite, evolving CO­(g), CO2(g), NH3(g), and H2O­(g). Therefore, struvite from GW sorbs metals and organics, and can release sorbed and structural components to the aqueous and gas phases.