Optimization of a nitrite-dependent anaerobic methane oxidation (n-damo) process by enhancing methane availability

Area of Science:

• Environmental microbiology
• Biogeochemical cycles

Background:

• Nitrite-dependent anaerobic methane oxidation (n-damo) is a promising process for methane removal.
• Development is hindered by low n-damo bacteria growth rates and specific activity.
• Enhancing methane availability is crucial for improving n-damo performance.

Purpose of the Study:

• To investigate the effects of immobilized biologically activated carbon (IC) and high static pressure (HP) on the n-damo process.
• To improve methane availability and enhance the performance of n-damo bacteria.
• To optimize the n-damo process for practical applications.

Main Methods:

• Utilized immobilized biologically activated carbon (IC) to increase methane absorption capacity.
• Applied high static pressure (HP) to enhance methane transfer to biomass.
• Combined IC and HP in a novel system (HP-IC) to assess synergistic effects.
• Employed quantitative PCR (q-PCR) to analyze n-damo bacteria growth rates and diversity.

Main Results:

• Both IC and HP individually improved n-damo bacteria activity.
• The HP-IC system achieved the highest n-damo specific activity (47.65 ± 0.21 µmol N L⁻¹ g⁻¹ h⁻¹).
• IC increased methane absorption capacity approximately 10-fold, facilitating methane supply.
• HP enhanced methane transfer due to a larger specific surface area of biomass.
• Both HP and IC promoted n-damo bacteria growth rates, with HP also enriching bacterial diversity.

Conclusions:

• Immobilized biologically activated carbon (IC) and high static pressure (HP) are effective strategies for enhancing the n-damo process.
• The combined HP-IC system significantly boosts n-damo bacteria activity, growth, and methane utilization.
• These findings offer a pathway to overcome limitations in n-damo process development and application.