Biofiltration of Methane, An Innovative Approach
In Canada, methane is, after carbon dioxide, the most important greenhouse gas. To control the emission of this compound, combustion is encouraged. Parallel to this policy, Canada favors the development of new simple and inexpensive technologies able to eliminate methane when combustion is not possible or too expensive, as for small or old landfills. For 4 years, the Biocom laboratory of the University de Sherbrooke (Quebec) has worked on this problem. The experiments undertaken to date were related primarily to biofiltration, a biological process proven reliable especially in the treatment of low inlet loads of methane. The studies carried out have allowed a better understanding of methane biofiltration by determining the real influence of key factors such as the inlet load, the type and quantities of nutrients, the type of filter bed, on the behavior and performance of the microorganisms. For example, we have determined that the use of an inorganic material is to be preferred in the case of methane biofiltration, instead of an organic material like compost. Indeed, elimination capacities of 35 g/m3/h can be obtained with inorganic material, which is superior to the value of 15 g/m3/h for compost, when methane concentration and gas flow rates are around 9500 ppmv and 0.25 m3/h respectively. In addition, the performance of our inorganic based-bed biofilter is among the best values reported in the literature and can be maintained for a period of over a year, contrary to conventional organic biofilters which keep their efficiency for 2 to 6 months.