[Effect of Temperature and pH on Nitrogen Conversion in Feammox Process]

Area of Science:

• Environmental microbiology
• Biogeochemical cycles
• Wastewater treatment

Background:

• Anaerobic ammonium oxidation (ANAMMOX) is a key process in nitrogen removal.
• Feammox, the oxidation of ammonium using Fe(III) anaerobically, is gaining attention for nitrogen conversion.
• Understanding environmental factors affecting Feammox is crucial for its application.

Purpose of the Study:

• To investigate the impact of pH and temperature on nitrogen transformation during the Feammox process.
• To assess the activity recovery of Feammox sludge.
• To identify factors interfering with continuous Feammox reactor operation.

Main Methods:

• Acclimation of anaerobic ammonium oxidation (ANAMMOX) sludge for Feammox.
• Monitoring nitrogen conversion (ammonia, nitrite, nitrate, total nitrogen) under varying pH and temperature.
• Analysis of sludge activity and interference factors like iron precipitation.

Main Results:

• Feammox sludge activity was recovered after 40 days of operation.
• Significant ammonia and total nitrogen removal was observed, producing mainly nitrate and nitrogen.
• Optimal conditions for high total nitrogen removal (>50%) were pH 7 and 30°C.
• Ammonia nitrogen conversion reached 80.2% at pH 6.5.
• Iron ion precipitation and sludge surface coating were identified as major operational interferences.

Conclusions:

• pH and temperature significantly influence nitrogen transformation in the Feammox process.
• Feammox demonstrates potential for effective nitrogen removal in anaerobic environments.
• Further research is needed to mitigate operational challenges caused by iron precipitation for sustained Feammox application.