Comparative study of methane oxidation within various biofilter media

Abstract

A considerable fraction of the methane gas generated by landfills can be oxidized by the landfill cover. In this study, the use of disposable sawdust material to utilize and reduce methane gas from the landfill gas (LFG) was demonstrated. Three laboratory scale bioreactors were constructed to reflect the performance of sawdust with respect to the compost and sand (control media). Patterns of methane (CH₄) oxidation were evaluated through the degree of methane oxidation in correlation to the bacterial development in all three media. Later, the use of nutrients during the respiration of the bacteria was interpreted through the analysis of chemical oxygen demand (COD), biochemical oxygen demand (BOD), and biomass growth variations. The overall methane oxidation efficiency in the sawdust medium was 60% with a biomass content of 238 g/m³, whereas the compost medium had 86% methane oxidation efficiency with a 539 g/m³ biomass content. Furthermore, the COS and BOD removal were 2555 mg/L and 332 mg/L from the compost, and 1984 mg/L and 156 mg/L from the sawdust respectively. The overall results of this study indicated that the sawdust material can be used as a biofilter media for methane utilization from the landfill. The oxidation capacity of sawdust could be accelerated by adding necessary nutrients to this media before implementation. Moreover, the oxidation rate variance between compost and sawdust may be eliminated over time due to nutrient exhaustion in the compost media, and/or production of usable carbon with decomposition of the sawdust media.