Achieving high nitrogen removal efficiency by optimizing nitrite-dependent anaerobic methane oxidation process with...

Area of Science:

• Environmental Microbiology
• Biotechnology
• Wastewater Treatment

Background:

• Nitrite-dependent anaerobic methane oxidation (N-DAMO) is a novel bioprocess converting methane and nitrite to dinitrogen.
• N-DAMO offers a sustainable approach for denitrification in wastewater treatment.
• Limited N-DAMO bacteria activity and growth hinder its widespread application.

Purpose of the Study:

• To investigate the effects of growth factors (vitamin, heme, nucleobase, betaine) on N-DAMO bacteria.
• To optimize N-DAMO process conditions for enhanced nitrogen removal.
• To assess the long-term performance and bacterial community dynamics in a bioreactor.

Main Methods:

• Short-term and long-term incubation experiments were conducted to evaluate growth factor efficacy.
• Optimized growth factor concentrations were applied in a magnetically stirred gas lift reactor (MSGLR).
• Bacterial community composition and nitrogen removal rates were monitored throughout the study.

Main Results:

• Nucleobase and betaine significantly stimulated N-DAMO activity at specific concentrations.
• N-DAMO bacteria abundance reached 14.4% within 300 days, with larger aggregate formation observed.
• The MSGLR achieved a nitrogen removal rate of 70 mg N L⁻¹ day⁻¹ and >99.0% efficiency.
• Betaine addition led to a significant methylotroph population, impacting N-DAMO enrichment.

Conclusions:

• Nucleobase and betaine are effective stimulants for N-DAMO bacteria.
• The study demonstrates the potential for high nitrogen removal efficiency using N-DAMO in bioreactors.
• Further research is needed to mitigate the impact of co-contaminants like betaine on N-DAMO enrichment for industrial application.