THE INFLUENCE OF THE GAS FLOW RATE DURING METHANE BIOFILTRATION ON AN INORGANIC PACKING MATERIAL

The influence of the gas flow rate (GFR), when varied between 1 and 5.5 L/min, on the conversion, the elimination capacity (EC) and the carbon dioxide production (P-CO2), during the biofiltration of methane using a biofilter charged with an inorganic packing material, has been investigated. The methane concentrations considered for this purpose were selected from the operating range of 1300-12000 ppmv. The experiments involved were conducted, using a nitrogen minimal salt nutrient solution, for the biofilter periodic irrigation, in which the nitrogen concentration was maintained at 0.75 g/L, and the phosphorus concentration was of 0.3 or 1.5 g/L. The results obtained from this study have confirmed the view that the GFR is a very important parameter, the optimum values found, leading to methane conversions of >90%, being <= 2 L/min for inlet loads <55 g/m(3)/h. Based on this result, it was then established that the maximum volumetric load (VL) of methane in the biofilter must be estimated at around 0.075 m(3) (methane)/m(3) (biofilter)/h, that is, 6.8 m(3) (polluted gas)/m(3) (biofilter)/h. In addition, when the GFR is selected between 1 and 4.2 L/min, it has an influence on the EC. However, the GFR does not affect the within the biofilter. It has also been established that the high phosphorus level (i.e., 1.5 g/L), present in the nutrient solution, is to P-CO2 be preferred in the biofilter.