Removal of the greenhouse gas methane by using autoclaved aerated concrete as matrix for colonization of methane‐oxidizing bacteria.

Abstract: Methane is an important greenhouse gas causing global warming. Compared to carbon dioxide, the effect on global warming is 34 times higher (probably even higher). Methane is released into the atmosphere by various sources. Landfills containing organic material are one important source. Today, the deposition of organic materials in landfills in Germany is forbidden. In other countries, it is still used. A major problem is that old landfills produce high amounts of methane by the decomposition of organic materials in anoxic zones over a long period of time after closure (more than 50 years). If the concentration of methane in the gas released from the landfill is between 40% and 60% (rich gas), the gas is withdrawn by suction and used for the production of electricity and heat by combustion. Below a level of 30% methane (poor gas), this technique is not efficient and methane is normally discharged into the atmosphere. We isolated methane‐oxidizing bacteria from various habitats and used them for colonization on mixtures of autoclaved aerated concrete (AAC) and sand‐lime brick rubble. Methane‐oxidizing bacteria oxidize methane via methanol, formaldehyde, and formate to carbon dioxide and water. In laboratory experiments, methane‐oxidizing bacteria were grown successfully on these artificial matrices. After adaption periods, they showed good microbial activity and high methane‐oxidation rates. In further experiments, we used this setup for a larger scale field experiment on a landfill site in Bremen. We built up a test field for long‐term measurements under realistic conditions. In this paper, we show the results obtained in our laboratory and field experiments and the problems that occurred. Nevertheless , this setup is an interesting option for the recycling of AAC and other building materials by using them as an active biofilter for the removal of methane emission from landfills. [ABSTRACT FROM AUTHOR]