High diversity of potential nitrate-reducing Fe(II)-oxidizing bacteria enriched from activated sludge

Area of Science:

• Environmental microbiology
• Wastewater treatment technologies
• Biogeochemical cycles

Background:

• Nitrate-dependent Fe(II) oxidation (NDFO) occurs in activated sludge.
• NDFO shows potential for removing nitrate from wastewater.
• Understanding microbial communities is crucial for optimizing NDFO.

Purpose of the Study:

• To enrich NDFO sludge from activated sludge.
• To investigate microbial community dynamics during NDFO enrichment.
• To identify key bacterial players in NDFO.

Main Methods:

• Enrichment of NDFO sludge over 100 days with high Fe(II).
• High-throughput sequencing of bacterial 16S rRNA genes.
• Analysis of microbial community structure and dominant genera.

Main Results:

• Successful enrichment of NDFO sludge with a denitrification rate of 1.37 mmol N/(gVSS day).
• Significant changes in microbial community structure observed.
• High diversity of potential Fe(II)-oxidizing bacteria (FeOB) identified, with Thermomonas and Gallionella as dominant genera.

Conclusions:

• NDFO can be effectively performed by enriched activated sludge.
• A diverse bacterial community, including Thermomonas and Gallionella, drives NDFO.
• Findings provide a basis for future NDFO research and engineering applications in wastewater treatment.