How to develop a bio-based phosphorus mining strategy for eutrophic marine sediments: Unlocking native microbial...

Area of Science:

• Environmental Science
• Geochemistry
• Microbiology

Background:

• Eutrophication in marine environments like the Baltic Sea leads to phosphorus accumulation in sediments.
• Anaerobic conditions can trigger the release of phosphorus from sediments, exacerbating eutrophication.
• Understanding factors influencing anaerobic phosphorus release is crucial for managing nutrient cycles.

Purpose of the Study:

• To examine the anaerobic release of phosphorus (P) from Baltic Sea sediments.
• To investigate the impact of volatile fatty acids (VFA), temperature, pH, and mixing on P release.
• To identify the role of sulfate-reducing bacteria (SRB) in anaerobic phosphorus release.

Main Methods:

• Batch bioreactor experiments using two Baltic Sea sediments (B and F).
• Varying initial concentrations of waste-derived volatile fatty acids (VFA) (1000-10000 mg COD/L).
• Testing different temperatures (20-35 °C), pH levels (5.5, 7.0, 8.5), and mixing conditions.
• Analysis of phosphorus, sulfate, and microbial community composition (SRB).

Main Results:

• Significant P release observed, up to 15.85 mg/L PO4-P for Sediment B at 10000 mg COD/L VFA.
• Lower VFA concentrations (1000 mg COD/L) resulted in maximum P releases of 4.4 mg/L (Sediment B) and 3.5 mg/L (Sediment F).
• Operation time and pH were statistically significant factors (p < 0.05) influencing P release; mixing was not significant.
• Sulfate reduction was extensive, with Desulfomicobiaceae dominating SRB, indicating their importance in anaerobic P release.

Conclusions:

• Volatile fatty acids can stimulate anaerobic phosphorus release from Baltic Sea sediments.
• pH and operation time are critical parameters controlling phosphorus release under anaerobic conditions.
• Sulfate-reducing bacteria play a key role in the anaerobic phosphorus release mechanism.
• Findings offer insights for potential phosphorus mining strategies in eutrophic environments.