Sulfur bacteria-reinforced microbial electrochemical denitrification

Area of Science:

• Environmental Science
• Microbiology
• Electrochemistry

Background:

• Microbial electrochemical denitrification (MED) is limited by the abundance and efficiency of functional microorganisms.
• Current methods of inoculating MED systems with denitrifying sludge require improvement.

Purpose of the Study:

• To compare the effectiveness of autotrophic denitrifying inoculum (ADI) versus heterotrophic denitrifying inoculum (HDI) for MED.
• To identify different microbial pathways and strategies for enhancing MED performance.

Main Methods:

• Comparison of MED systems inoculated with ADI and HDI.
• Analysis of electroactivity duration, denitrification efficiency, and microbial community composition.
• Investigation of biocathode metabolic pathways, including polysaccharide and protein content.

Main Results:

• ADI exhibited electroactivity for 50% less time than HDI.
• The ADI biocathode achieved 42% higher denitrification efficiency than the HDI biocathode.
• HDI biocathodes were rich in polysaccharides, suggesting interspecies electron transfer, while ADI biocathodes were protein-rich, indicating direct electron uptake by sulfur bacteria.

Conclusions:

• Autotrophic sulfur-oxidizing denitrifiers offer a viable strategy for enhancing MED.
• ADI can significantly improve denitrification efficiency in MED systems compared to HDI.
• Different microbial communities utilize distinct pathways to achieve MED.