Mechanically-biologically treated municipal solid waste as a support medium for microbial methane oxidation to mitigate landfill greenhouse emissions
Tutkimustuotos › › vertaisarvioitu
|DOI - pysyväislinkit|
|Tila||Julkaistu - 2008|
The residual fraction of mechanically-biologically treated municipal solid waste (MBT residual) was studied in the laboratory to evaluate its suitability and environmental compatibility as a support medium in methane (CH4) oxidative biocovers for the mitigation of greenhouse gas emissions from landfills. Two MBT residuals with 5 and 12 months total (aerobic) biological stabilisation times were used in the study. MBT residual appeared to be a favourable medium for CH4 oxidation as indicated by its area-based CH4 oxidation rates (12.2-82.3 g CH4 m-2 d-1 at 2-25 °C; determined in CH4-sparged columns). The CH4 oxidation potential (determined in batch assays) of the MBT residuals increased during the 124 d column experiment, from <1.6 to a maximum of 104 μg CH4gdw - 1 h-1 (dw = dry weight) at 5 °C and 578 μg CH4gdw - 1 h-1 at 23 °C. Nitrous oxide (N2O) production in MBT residual (<15 μg N2Okgdw - 1 d-1 in the CH4 oxidative columns) was at the lower end of the range of N2O emissions reported for landfills and non-landfill soils, and insignificant as a greenhouse gas source. Also, anaerobic gas production (25.6 lkgdw - 1 during 217 d) in batch assays was low, indicating biological stability of the MBT residual. The electrical conductivities (140-250 mS m-1), as well as the concentrations of zinc (3.0 mg l-1), copper (0.5 mg l-1), arsenic (0.3 mg l-1), nickel (0.1 mg l-1) and lead (0.1 mg l-1) in MBT residual eluates from a leaching test (EN-12457-4) with a liquid/solid (L/S) ratio of 10:1, suggest a potential for leachate pollutant emissions which should be considered in plans to utilise MBT residual. In conclusion, the laboratory experiments suggest that MBT residual can be utilised as a support medium for CH4 oxidation, even at low temperatures, to mitigate greenhouse gas emissions from landfills.