Suitability assessment of dumpsite soil biocover to reduce methane emission from landfills under interactive influence of nutrients.

Biocovers are known for their role as key facilitator to reduce landfill methane (CH4) emission on improving microbial methane bio-oxidation. Methanotrophs existing in the aerobic zone of dumped wastes are the only known biological sinks for CH4 being emitted from the lower anaerobic section of landfill sites and even from the atmosphere. However, their efficacy remains under the influence of landfill environment and biocover characteristics. Therefore, the present study was executed to explore the suitability and efficacy of dumpsite soil as biocover to achieve enhanced methane bio-oxidation under the interactive influence of nutrients, carbon source, and environmental factors using statistical-mathematical models. The Placket-Burman design (PBD) was employed to identify the significant factors out of 07 tested factors having considerable impact on CH4 bio-oxidation. The normal plot and Student's t test of PBD indicated that ammonical nitrogen (NH4+-N), nitrate nitrogen (NO3--N), methane (CH4), and copper (Cu) concentration were found significant. A three-level Box-Behnken design (BBD) was further applied to optimize the significant factors identified from PBD. The BBD results revealed that interactive interaction of CH4 with NH4+-N and NO3--N affected the CH4 bio-oxidation significantly. The sequential statistical approach predicted that maximum CH4 bio-oxidation of 27.32 µg CH4 h-1 could be achieved with CH4 (35%), NO3--N (250 µg g-1), NH4+-N (25 µg g-1), and Cu (50 mg g-1) concentration. Conclusively, waste dumpsite soil could be a good alternative over conventional soil cover to improve CH4 bio-oxidation and lessen the emission of greenhouse gas from waste sector.

Statistical assessment of dumpsite soil suitability to enhance methane bio-oxidation under interactive influence of substrates and temperature.

Biocovers are considered as the most effective and efficient way to treat methane (CH4) emission from dumpsites and landfills. Active methanotrophs in the biocovers play a crucial role in reduction of emissions through microbiological methane oxidation. Several factors affecting methane bio-oxidation (MOX) have been well documented, however, their interactive effect on the oxidation process needs to be explored. Therefore, the present study was undertaken to investigate the suitability of a dumpsite soil to be employed as biocover, under the influence of substrate concentrations (CH4 and O2) and temperature at variable incubation periods. Statistical design matrix of Response Surface Methodology (RSM) revealed that MOX rate up to 69.58µgCH4g-1dwh-1 could be achieved under optimum conditions. MOX was found to be more dependent on CH4 concentration at higher level (30-40%, v/v), in comparison to O2 concentration. However, unlike other studies MOX was found in direct proportionality relationship with temperature within a range of 25-35°C. The results obtained with the dumpsite soil biocover open up a new possibility to provide improved, sustained and environmental friendly systems to control even high CH4 emissions from the waste sector.