Methane biofiltration using autoclaved aerated concrete as the carrier material

Area of Science:

• Environmental microbiology
• Biotechnology
• Environmental engineering

Background:

• Methane (CH4) is a potent greenhouse gas, necessitating effective mitigation strategies.
• Biofilters utilizing methane-oxidizing bacteria (MOB) offer a sustainable approach for methane removal.
• Autoclaved aerated concrete (AAC) presents a novel, highly porous material for microbial immobilization.

Purpose of the Study:

• To evaluate the methane removal capacity of a mixed MOB culture immobilized on AAC in a biofilter.
• To optimize MOB immobilization and biofilter performance using AAC as a carrier material.
• To assess the long-term stability and efficiency of the AAC-based biofilter for low-concentration methane removal.

Main Methods:

• Batch experiments were conducted to optimize MOB immobilization on AAC specimens.
• Optimized conditions included using 10-mm-thick AAC without calcium chloride during inoculation.
• A biofilter setup was used to test the methane removal capacity of immobilized MOB over 127 days.

Main Results:

• Optimum methane removal was achieved with 10-mm AAC specimens and no calcium chloride addition during inoculation.
• The immobilized MOB achieved an average removal efficiency (RE) of 28.7% for low-concentration methane (~1000 ppmv).
• MOB exhibited higher abundance at the biofilter base, near the methane inlet, correlating with higher methane concentrations.

Conclusions:

• Autoclaved aerated concrete (AAC) is an efficient carrier material for developing methane biofilters.
• The developed biofilter demonstrates sustained methane removal capacity over an extended period.
• Further optimization could enhance the overall methane removal efficiency of AAC-based biofilters.