Simultaneous Phosphorus Recovery from Phosphorus-Rich Groundwater and Phosphorus Slag: Insights into Struvite Formation and Environmental Co-benefits

Effective recovery of phosphorus (P) from water bodies can reduce the global shortage of P resources. Struvite formation represents one of the optimal strategies for P recovery and is widely used in wastewater treatment. However, recovery of P from P-rich groundwater via struvite remains underexplored. This study assessed three P recovery methods from groundwater containing elevated concentrations of phosphate, calcium, iron, and fulvic acid (FA). The results showed that high concentrations of calcium significantly inhibited the formation of struvite, while iron and FA exhibited comparatively limited inhibitory effects. The synergistic interaction of these three components constitutes a critical determinant for struvite formation in groundwater. Direct precipitation and ion exchange methods proved to be suboptimal for P recovery due to their low purity (∼10%). The dual-waste utilization method markedly enhanced the purity of struvite to about 35%, enabling the simultaneous recovery of solid and liquid P. The dual-waste utilization method showed superior or equivalent environmental impacts compared to the other two methods. Overall, integrating P-rich groundwater with P slag for struvite formation provides multiple benefits, including groundwater remediation, waste recycling, and fertilizer production through beneficial resource symbiosis.