Recovering nitrogen and phosphorus through struvite (MgNH4PO4·6H2O) crystallization from swine wastewater has gained increasing interest. However, swine wastewater contains complex compositions, which may hinder the formation of struvite crystal and affect the purity of the precipitates by forming other insoluble minerals. In this work, experiments were carried out to evaluate struvite precipitation in the anaerobically digested swine wastewater, with dosing bittern as a low-cost magnesium source. Exceeded 90% phosphate removal and 23–29% ammonium reduction were obtained. FTIR, XRD and mass balance analysis were combined to analyze the species of precipitated minerals. Results showed that the precipitates were struvite, mixed with amorphous calcium phosphate (ACP) and brucite. The presence of Ca2+ diminished the percentage of struvite and gave rise to ACP formation. Controlling pH below 9.5 and bittern dosage above 1% (w/w) could inhibit ACP precipitation and harvest a highly pure struvite crystal product.
Recovering phosphorus as struvite from the digested swine wastewater with bittern as a magnesium source
Zhi-Long Ye, Shao-Hua Chen, Min Lu, Jian-Wen Shi, Li-Feng Lin, Shu-Mei Wang; Recovering phosphorus as struvite from the digested swine wastewater with bittern as a magnesium source. Water Sci Technol 1 July 2011; 64 (2): 334–340. doi: https://doi.org/10.2166/wst.2011.720
Download citation file: