Oxidation of methane in biotrickling filters inoculated with methanotrophic bacteria.

The oxidation of methane (CH) using biofilters has been proposed as an alternative to mitigate anthropogenic greenhouse gas emissions with a low concentration of CH that cannot be used as a source of energy. However, conventional biofilters utilize organic packing materials that have a short lifespan, clogging problems, and are commonly inoculated with non-specific microorganisms leading to unpredictable CH elimination capacities (EC) and removal efficiencies (RE). The main objective of this work was to characterize the oxidation of CH in two biotrickling filters (BTFs) packed with polyethylene rings and inoculated with two methanotrophic bacteria, Methylomicrobium album and Methylocystis sp., in order to determine EC and CO production (pCO) when using a specific inoculum. The repeatability of the results in both BTFs was determined when they operated at the same inlet load of CH. A dynamic mathematical model that describes the CH abatement in the BTFs was developed and validated using mass transfer and kinetic parameters estimated independently. The results showed that EC and pCO of the BTFs are not identical but very similar for all the conditions tested. The use of specific inoculum has shown a faster startup and higher EC per unit area (0.019 gCH m h) in comparison to most of the previous studies at the same CH load rate (23.2 gCH m h). Global mass balance showed that the maximum reduction of CO equivalents was 98.5 gCO m h. The developed model satisfactorily described CH abatement in BTFs for a wide range of conditions.