Anode potential selection for sulfide removal in contaminated marine sediments

Area of Science:

• Environmental microbiology
• Electrochemistry
• Biogeochemistry

Background:

• Sulfate-reducing microorganisms in marine sediments biodegrade hydrocarbons, producing toxic sulfide.
• Efficient removal of this toxic sulfide is crucial for environmental remediation.

Purpose of the Study:

• To determine the optimal anodic potential for efficient toxic sulfide removal via (bio)electrochemical methods.
• To evaluate the role of the sulfur-oxidizing bacterium Desulfobulbus propionicus in sulfide removal and sulfur cycling.

Main Methods:

• Testing (bio)electrochemical sulfide removal at different anodic potentials (-205 mV, +195 mV, +300 mV vs Ag/AgCl).
• Monitoring current production, sulfide, and sulfate concentrations over time.
• Characterizing sulfur deposition using SEM-EDS and microbial communities via 16S rRNA gene sequencing.

Main Results:

• Current production correlated with sulfide removal.
• Desulfobulbus propionicus facilitated the back-oxidation of deposited sulfur to sulfate.
• +195 mV (vs Ag/AgCl) yielded the highest electron recovery.
• -205 mV (vs Ag/AgCl) resulted in the lowest sulfur deposition on the anode.

Conclusions:

• Anodic potential significantly influences the efficiency of (bio)electrochemical sulfide removal.
• Desulfobulbus propionicus can be utilized to enhance sulfur cycling and mitigate sulfide toxicity.
• Anodic potential of +195 mV is optimal for maximizing electron recovery during sulfide removal.