Unveiling the impact of carbon sources on phosphorus release from sediment: Investigation of microbial interactions and metabolic pathways for anaerobic phosphorus recovery
o enhance the recovery of phosphorus (P) from marine sediment, our results revealed the influence of P release from the sediment stimulated with different types and concentrations of carbon sources. During 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%. The excessive addition of carbon sources 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. For instance, 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 a close relationship between microbial activities involved in P and sulfur cycling, showing a significant positive correlation with the abundance of corresponding functional genes (phoD, cysD). The P-enriched supernatant generated from the bioreactors holds promise as a valuable source for future recovery efforts.