Unveiling the impact of carbon sources on phosphorus release from sediment: Investigation of microbial interactions and metabolic pathways for anaerobic phosphorus recovery

The aim of this study was recovery of phosphorus (P) from marine sediment, and our results revealed the influence of P release from the sediment stimulated with different types and concentrations of carbon sources. During the 15-day anaerobic operation, the sediments stimulated with 1 g/L propionic acid and glucose exhibited more prominent effects compared to other trials, with 5.98 mg/L and 6.44 mg/L of P released, respectively, with a total solid content of 4 %. Notably, the excessive addition of carbon sources was shown to can partially inhibit P release. As microbial activity intensified, P was utilized for microbial synthesis, resulting in a decreased P in the supernatant. For example, in glucose-fed systems with concentrations of 5 g/L and 10 g/L, the P concentration decreased from 5 mg/L on Day 3 to approximately 3 mg/L on Day 15. The sequencing results indicated distinct evolutions within different carbon source-fed systems over the 15-day operations. Feeding high concentrations of glucose resulted in rapid enrichment of fermentative bacteria under anaerobic conditions, while sulfate-reducing bacteria promoted P release in volatile fatty acids-fed systems. Metabolic analysis revealed that carbon sources not only influence gene expression in different systems, but also impact the metabolic pathways involved in nutrient cycling, which can be interrelated. For example, a significant positive correlation was observed between the abundance of P and sulfur cycling functional genes (phoD, cysD).