High specific activity for anammox bacteria enriched from activated sludge at 10°C

Area of Science:

• Environmental microbiology
• Wastewater treatment technologies
• Biogeochemical cycles

Background:

• Anammox (anaerobic ammonium oxidation) process in wastewater treatment plants (WWTPs) offers energy savings and biogas recovery.
• Low temperatures (<20°C) in the water line significantly reduce anammox specific activity, posing a major challenge for application.

Purpose of the Study:

• To enrich a cold-adapted anammox species with high specific activity for low-temperature wastewater treatment.
• To identify dominant anammox species and quantify their activity and biomass yield under cold conditions.

Main Methods:

• Operation of a 4.2L reactor at 10°C with a specific influent loading of 61 mg (NH4+NO2)-N/L.
• Inoculation with activated sludge from two municipal WWTPs to enrich for cold-adapted anammox bacteria.
• Monitoring of anammox specific activity and biomass yield.

Main Results:

• Enrichment of a cold-adapted anammox biomass dominated by Candidatus Brocadia fulgida.
• Achieved specific anammox activity of 30-44 mg N/(g VS d) at 10°C, which is double previous reports for this temperature.
• Observed biomass yield of 0.046 g biomass/g N converted, comparable to higher temperatures.

Conclusions:

• Successful enrichment of a highly active, cold-adapted anammox species is feasible.
• The high specific activity at 10°C demonstrates the potential for full-scale application of anammox in cold wastewater streams.
• The process maintains efficient nitrogen conversion and biomass production even at low temperatures.