Development of a denitrification system using primary sludge as solid carbon source - Potential to couple with...

Area of Science:

• Environmental Microbiology
• Wastewater Treatment Engineering
• Biogeochemical Cycles

Background:

• Heterotrophic denitrification is crucial for nitrogen removal but often limited by carbon sources in wastewater.
• Primary sludge, a wastewater by-product, presents a potential alternative carbon source.
• High-strength nitrite wastewater poses treatment challenges due to carbon deficiency.

Purpose of the Study:

• To investigate the feasibility of using primary sludge as a carbon source for heterotrophic denitrification of high-strength nitrite wastewater.
• To determine the optimal primary sludge dosage for efficient nitrite removal.
• To analyze the microbial community and identify potential co-occurring processes like anammox.

Main Methods:

• Experimental investigation of denitrification using primary sludge.
• Optimization of primary sludge dosage (g VSS/g N).
• Microbial community analysis using molecular techniques.

Main Results:

• Successful nitrogen removal from high-strength nitrite wastewater (400-1200 mg N/L) using primary sludge.
• Optimal primary sludge dosage identified as 3.6 g VSS/g N for complete nitrite removal.
• Detection of simultaneous ammonium removal and identification of denitrifying bacteria, organic degrading bacteria, and Candidatus Brocadia (anammox bacteria).

Conclusions:

• Primary sludge is a viable and promising alternative carbon source for wastewater denitrification.
• The slow release of carbon from primary sludge may facilitate the anammox process.
• Coupling denitrification with anammox offers a potential strategy for enhanced nitrogen removal and reduced ammonium residue.