Implementation of the Anammox process for improved nitrogen removal

Area of Science:

• Environmental microbiology
• Wastewater treatment engineering

Background:

• Increasingly stringent regulations on nitrogen discharge necessitate advanced wastewater treatment solutions.
• Anaerobic ammonium oxidation (Anammox) presents a promising biological approach for nitrogen removal, particularly from high-strength nitrogenous wastewaters.

Purpose of the Study:

• To evaluate the long-term performance and microbial dynamics of the Anammox process in a completely stirred tank reactor (CSTR) treating synthetic wastewater.
• To assess the impact of increasing nitrogen loads on Anammox process efficiency and biomass composition.

Main Methods:

• Operation of a CSTR for 511 days with gradually increasing ammonium and nitrite loads.
• Monitoring of ammonium and nitrite utilization rates and conversion efficiencies.
• Microbial community analysis using Fluorescence in situ Hybridization (FISH) to identify dominant species.

Main Results:

• Sustained high removal efficiencies: 90% ammonium and over 99% nitrite conversion.
• Observed increase in ammonium and nitrite utilization rates correlating with rising nitrogen loads.
• Reactor restart after biomass removal at day 272, with subsequent stable performance.
• Dominance of Candidatus "Brocadia anammoxidans" strain Dokhaven 2 in the microbial community.

Conclusions:

• The Anammox process, particularly with Candidatus "Brocadia anammoxidans", is robust and efficient for treating high-strength ammonium wastewater.
• The process demonstrates adaptability to increasing nitrogen loads, maintaining high removal rates.
• Long-term operation in a CSTR is feasible for sustainable ammonium removal via Anammox.