Development of a biofilter for the removal of methane from coal mine ventilation atmospheres

Abstract

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, Methylomonasfodinarum 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%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 02 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.

Elimination of methane generated from landfills by biofiltration: a review

“…An experiment, involving biofiltration by percolation with glass particles, has been reported (Sly et al 1993). For a residence time of 20 min and an IL of around 200 g m -2 d -1 , more than 95% of CH 4 conversion was achieved.…”

Air Treatment Techniques for Abatement of Emissions from Intensive Livestock Production

“…The linear relationship that is shown in Figure 5.4, with a k value of 2.5 hour -1 , indicates that indeed first-order kinetics occur. This k value corresponds to the range from 0.3 to 6.6 hour -1 that can be calculated from the data of other studies at logarithmic mean methane concentrations from 0.4 to 22 g m -3 (Sly et al, 1993;Du Plessis et al, 2003;Streese and Stegmann, 2003). Finally, the methane elimination capacity that was observed, at an average air inlet temperature of 12°C, may significantly increase if the biofilter is operated at a higher temperature.…”

“…Although most recent literature (Devinny et al, 1999;Kennes et al, 2001) suggests that bioreactors are only cost-effective up to pollutant concentrations of 5 to 10 g m -3 , for landfill-gas treatment biofilters have been developed and operated at various methane inlet concentrations up to 260 g m -3 (40% v/v) at empty bed air residence times (EBRT's) between 5 minutes and 5 hours (Figueroa, 1996;Kussmaul and Gebert, 1998;Dammann et al, 1999;Straka et al, 1999;Scharff et al, 2001;Park et al, 2002;Gebert et al, 2003;Streese and Stegmann, 2003;Park et al, 2004), whereas typical EBRT's are 25 seconds to over a minute for common biofilter applications (Devinny et al, 1999). Also some papers were published on biofiltration of coalmine atmospheres that are usually controlled at a methane content of 1 to 10 g m -3 (Apel et al, 1991;Sly et al, 1993;Du Plessis et al, 2003). An alternative technology for removal of high pollutant concentrations, such as activated carbon adsorption, is not suitable for treatment of methane containing air because of the low methane affinity for adsorbents.…”

Stripping and Dissipation Techniques for the Removal of Dissolved Gases From Anaerobic Effluents

“…Thus, while the content of hydrogen sulfide would have an important reduction, to around 500 ppm, the methane content would drop to values as low as 6% in the mixture of biogas and waste gas, posing serious difficulties and technical problems, including risks of an explosive atmosphere within the range of 5 to 15% CH 4 (Noyola et al 2006). On the other hand, in research related to landfills, coal mining and piggery, there are many studies on biofiltration of CH 4 at low concentrations (250-50,000 ppm v ), since in these fields problems related to greenhouse gas emissions are well known (Sly et al, 1993;Melse and Vander Werf, 2005;Gebert and Gröngröft, 2006;Nikiema et al, 2007;Park et al, 2009). However, we did not find in the literature any study regarding the removal of CH 4 from waste gases generated in anaerobic reactors used for the treatment of domestic wastewater, possibly because of the different requirements for the biofiltration of CH 4 in relation to odorant compound biofiltration and because of CH 4 mass-transfer limitatios in biofilms, which often reduce the abatement potential or lead to an empty bed residence time (EBRT) extremely high.…”