Methane-dependent denitrification by a semi-partitioned reactor supplied separately with methane and oxygen

Area of Science:

• Environmental Microbiology
• Chemical Engineering
• Green Chemistry

Background:

• Methane (CH4) is a potential carbon source for denitrification, but its use with oxygen (O2) in reactors poses safety and environmental risks.
• Unused CH4 and O2 in reactor off-gas are unusable for fuel, risk explosion, and contribute to the greenhouse effect.

Purpose of the Study:

• To test a novel reactor design for methane-dependent denitrification (MDD) that mitigates risks associated with CH4-O2 mixtures.
• To evaluate the reactor's ability to maintain MDD activity, ensure off-gas safety, and reduce methane leakage.

Main Methods:

• A novel reactor with a partition was designed to supply CH4 and O2 separately to the liquid phase.
• MDD activity was compared between mixed and separate gas supply methods.
• Off-gas composition, fuel usability, and methane concentration in effluent were analyzed.

Main Results:

• MDD activity was comparable to mixed gas supply when CH4 and O2 were supplied separately.
• Separate gas supplies resulted in usable fuel gas (high CH4, low O2) and low-methane off-gas.
• Optimizing the CH4/O2 ratio and effluent draw-off point reduced dissolved methane in the effluent.

Conclusions:

• The novel partitioned reactor enhances the safety of MDD processes.
• This design facilitates the reuse of methane as a fuel source.
• The reactor effectively reduces methane emissions into the atmosphere.