Oxidation of methane in biotrickling filters inoculated with methanotrophic bacteria
2017
Cáceres Sánchez, Manuel | Dorado, Antonio D. | Gentina, Juan C. | Aroca, Germán
The oxidation of methane (CH₄) using biofilters has been proposed as an alternative to mitigate anthropogenic greenhouse gas emissions with a low concentration of CH₄ 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 CH₄ elimination capacities (EC) and removal efficiencies (RE). The main objective of this work was to characterize the oxidation of CH₄ 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 CO₂ production (pCO₂) when using a specific inoculum. The repeatability of the results in both BTFs was determined when they operated at the same inlet load of CH₄. A dynamic mathematical model that describes the CH₄ abatement in the BTFs was developed and validated using mass transfer and kinetic parameters estimated independently. The results showed that EC and pCO₂ 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 gCH₄ m⁻² h⁻¹) in comparison to most of the previous studies at the same CH₄ load rate (23.2 gCH₄ m⁻³ h⁻¹). Global mass balance showed that the maximum reduction of CO₂ equivalents was 98.5 gCO₂ₑq m⁻³ h⁻¹. The developed model satisfactorily described CH₄ abatement in BTFs for a wide range of conditions.
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