Recovering phosphorus as struvite microspheres with multiple excellent application performance via crystallization method

Phosphorus (P) recovery from wastewater as struvite not only alleviates global P resource shortages but also prevents water eutrophication caused by wastewater discharge. This study presents a sodium dodecyl benzene sulfonate (SDBS)-assisted struvite crystallization method (SASC method) to recover P as the struvite crystalline microspheres with uniform particle size (27.51 ± 3.60 μm), high sphericity (roundness = 0.91 ± 0.04), and good dispersibility (no aggregation) under various operating conditions with different N/P/Mg molar ratios and magnesium sources. Mechanism of microsphere formation and the regulation of modifier type and process parameters (SDBS concentration, initial pH, and stirring rate) on microsphere formation are explored in detail to realize the controllable fabrication of microspheres. Compared with common struvite crystals, microspheres have more outstanding performance in multiple applications. Specifically, microspheres have improved powder properties including bulk density and fluidity, better slow-release fertilizer performance, that is, slower dissolution in water and soil, and the ability to prepare superior mesoporous phosphate materials with better macroscopic morphology and higher loading capacity. Thus, this study markedly improves the multiple application performance of struvite by designing and controlling the product morphology based on its simplicity and efficiency. These provide new insights into recovering P in the form of struvite with excellent quality, thereby enhancing the economic value of the recycled products of P recovery from wastewater