Novel high-purity struvite crystallization method for phosphate recovery from simulated swine wastewater using activated talcum

The struvite crystallization method is considered a highly promising approach for phosphate recovery from swine wastewater. However, the utilization of chemicals like magnesium and alkali as sources for struvite crystallization substantially increases the overall cost of this technology. In this study, activated talcum powder (ATP) was used instead of chemical reagents to recover phosphate as struvite from simulated swine wastewater containing 93 mg/L phosphorus and 450 mg/L ammonia nitrogen. The results showed that 93.02 ± 1.56% phosphorus and 14.47 ± 1.89% ammonia nitrogen were removed from simulated wastewater in the continuous flow circulation system. The purity of the struvite collected is as high as 97.24%. Mineralogical analysis showed that mechanical activation destroyed the crystal structure of talcum and increased the reactivity of Mg2+ and OH-, allowing it to be released spontaneously into aqueous solution. The amount of magnesium ions dissolved was affected by factors such as contact time, talcum dose, ammonium concentration and pH. The main components of ATP residue were quartz and magnesite, which will not cause secondary pollution to the environment. The use of ATP to recover phosphate into struvite has the advantages of low chemical cost and no pollution of waste materials, holding broad application prospects.