Operational strategy for nitrogen removal from centrate in a two-stage partial nitrification--anammox process

Area of Science:

• Environmental Engineering
• Microbial Ecology
• Wastewater Treatment

Background:

• Centrate from wastewater treatment plants contains high ammonium concentrations.
• Nitrogen removal is crucial for preventing eutrophication.
• Partial Nitrification (PN) followed by Anaerobic Ammonium Oxidation (Anammox) is an efficient nitrogen removal strategy.

Purpose of the Study:

• To present an operational strategy for nitrogen removal from wastewater centrate.
• To evaluate a two-stage PN-Anammox process.
• To compare the performance of different Anammox reactor configurations.

Main Methods:

• Partial nitrification was performed in a sequencing batch reactor (SBR).
• Anammox treatment was conducted in moving bed hybrid and up-flow fixed-bed biofilm reactors.
• Operational parameters like dissolved oxygen and feeding strategy were optimized.

Main Results:

• The PN stage achieved 49.5% ammonium conversion to nitrite with reduced HRT.
• The hybrid Anammox reactor removed 55.8% NH4-N, while the fixed-bed reactor removed 48.3%.
• Optimal ammonium removal in Anammox reactors occurred at a nitrite to ammonium ratio of 1.35–1.45.

Conclusions:

• The coupled PN-Anammox process is effective for ammonium removal from centrate.
• Reactor configuration impacts Anammox performance, with the hybrid reactor showing higher efficiency.
• Alkalinity does not limit the Anammox reaction under the studied conditions.