Optimization of Magnesium-Ammonium-Phosphate (Struvite) Precipitation for Nutrient Recovery from Synthetic Distilling Wastewater

Abstract

Phosphorus (P) and nitrogen (N) are finite yet indispensable nutrients whose excessive discharge into aquatic systems accelerates eutrophication, while their depletion from natural reserves poses a global sustainability concern. This study explores the optimization of struvite (MgNH₄PO₄·6H₂O) precipitation as a cost-effective and environmentally sound approach for nutrient recovery from synthetic distillery wastewater. Batch experiments were conducted to investigate the influence of the molar ratios of NH₄:PO₄ (1:1--5:1) and Mg:PO₄ (1:1--2:1) at a controlled pH of 9.0 under ambient conditions. The maximum nutrient recovery was observed for NH₄:PO₄ (3:1) and Mg:PO₄ (1.5:1), with 98.5% phosphate and 96.5% ammonium removal efficiencies. The purity of the recovered struvite, as determined through ammonium nitrogen quantification and X-ray diffraction (XRD) analysis, confirmed the predominance of crystalline struvite phases. These findings underscore that optimal molar ratios significantly enhance nutrient crystallization kinetics and product quality. This work demonstrates the potential of controlled struvite precipitation as a scalable pathway for nutrient circularity and sustainable wastewater management within the distillery sector.

Keywords: Struvite crystallization, nutrient recovery, magnesium-ammonium-phosphate, wastewater valorization, optimization, resource recovery.