Abstract

Struvite (MgNH4PO4 & centerdot;6 H2O) is a mineral recovered from wastewater that offers a sustainable source of phosphorus (P) for agriculture. However, its limited solubility may constrain its agronomic potential. This study aimed to assess the characteristics of wastewater-derived struvite and its effectiveness as a P fertilizer when combined with the phosphate-solubilizing yeast Naganishia albida. Struvite was collected from a municipal wastewater treatment plant and analyzed for elemental composition, solubility, and mineralogical structure. The phosphate-solubilizing activity of Naganishia. albida was evaluated using struvite as a P source. A greenhouse bioassay with lettuce (Lactuca sativa L.) was conducted using a bifactorial design combining three fertilization treatments (control, triple superphosphate (TSP), and struvite) with or without Naganishia albida inoculation. The results showed struvite presented 9.4% P content and met EU fertilizer quality criteria. Inoculation with Naganishia albida enhanced struvite solubilization, increasing soluble P to 1454.1 mg L- 1 and reducing pH to 5.6. Bioassays revealed that struvite combined with Naganishia albida enhanced P and Nitrogen (N) bioavailability by up to 24.7% and 31.6%, respectively. This combination achieved a peak RAE of 283%, outperforming both control and TSP treatments and demonstrating struvite competitiveness as a sustainable P source. This work introduces a novel approach by integrating struvite recovery with microbial P-enhancement using Naganishia albida, a rarely studied yeast, to develop a high-efficiency, slow-release non-conventional fertilizer. Our results highlight its potential as a sustainable alternative to synthetic P fertilizers, supporting nutrient recycling and circular economy practices in agriculture.