Abstract:
There are very limited studies on landfill gas on uncontrolled open dumps in developing
countries. In this study, landfill gas samples at 1 m depth from an abandoned open dump (AOD) in the
Central Province of Sri Lanka (N 7º 09', E 80º 35') were collected and the typical landfill gas composition
such as O2, N2, CH4, CO2, H2, H2S, and N2O were measured. Buried waste samples at 1 m depth were
also taken from the site and organic carbon and nitrogen contents in the residue (< 2 mm) were
measured. The samples were taken from some marked plots inside the dump with waste ages of around
0.5 and 7 years (AOD0.5 and AOD7) and outside intact (AODint).
Measured CH4 concentration for AOD0.5 and AOD7 ranged in 19–58 % and 0–12 %, respectively,
suggesting that the dumped waste at 1 m depth was in the process to be the ‘stabilization phase’ at least
7 years after dumping. This is likely to be a much shorter time period to reach the phase after dumping
than those in mid-latitude regions (typically in several decades). The carbon contents in the waste residue
in AOD0.5 and AOD7 were 151±67 and 29±7 mg g-1, respectively, implying that high waste decomposition
and leaching of organic compounds might have been enhanced due to high temperature and precipitation
at the site. A further study for the landfill gas and waste quality in the deeper layer is required to judge
whether whole of the dumpsite had reached the stabilization phase rapidly.
