DEVELOPMENT OF A BIOFILTER FOR THE REMOVAL OF METHANE FROM COAL-MINE VENTILATION ATMOSPHERES

Several strains of methane-oxidizing bacteria were isolated and studied to determine their physiological suitability for removal of methane in coal mine atmospheres. One strain, Methylomonas fodinarum ACM 3268, was selected as the most suitable culture for use in the development of a continuous biofilter to be used as a ventilation ''air scrubber''. The experimental biofilter utilising a biofilm of M. fodinarum was shown to reduce methane levels substantially provided the residence times were sufficiently long. In the range 0.25-1.0% methane in air, commonly experienced in coal mine atmospheres, more than 70% of the methane was removed with a residence time of 15 min, with a 90% reduction at 20 min. Even at a residence time of 5 min approximately 20% of the methane in air was removed. Equal quantities of O2 are consumed during the bacterial oxidation of methane and 1% methane is converted to 0.7% CO2. Scale-up and alternative biofilter packings are likely to reduce the residence times in the biofilter.