No abstract

No abstract

The methane oxidizing capacity of landfill cover soils was investigated through column and batch experiments by simulating conditions that are usually encountered in tropical climates. The rate of oxidation was monitored at different temperatures and moisture contents. It was observed that a low moisture content of 6% produced negligible oxidation, whereas oxidation rates were at a maximum at moisture contents between 15 and 20%. Temperature was found to be a dominant parameter which controlled the oxidation rates. The optimum temperature was between 30 and 36°C. In the column tests, the temperature influenced the methane oxidation capacity indirectly by causing the topsoil surface to become totally dry, resulting in almost zero oxidation in spite of aerobic conditions. Although some increase in oxidation rate was observed, a higher concentration of methane could not produce a corresponding increase in oxidation rates, indicating the limiting capacity of the soil to oxidize methane. A depth profile of the gas in the column system indicated that the depth of maximum oxidation was around 15 to 40 cm under normal test conditions. Experimental results indicated that the topsoil, if maintained at an optimum moisture content, could also produce a higher oxidation capacity. The results of this experimental program indicate the possibility of maximum methane oxidation in a tropical climate if the correct moisture content is maintained at the top surface.

The increasing municipal solid waste (MSW) generation along with the high fraction of organic waste and a common disposal of open dumping is the current scenario in many areas in Thailand. As a response to this problem, the country's Pollution Control Department (PCD) aims to reduce the MSW generation rate to less than 1 kg/capita/day, increase the collection efficiency, and improve the recovery of recyclables. For many years, more than 60% of the solid waste disposal system in Thailand has been carried out by open dumping. According to the survey conducted by this study, in 2004 there were 425 disposal sites (95 landfills; 330 open dumps) in Thailand and an estimated methane emission of 115.4 Gg/year was generated based on this practice. It has been estimated that the anticipated methane emission in Thailand will rise from 115.4 Gg/year to 118.5 Gg/year if the largest open dumpsites in provinces with no existing landfill are upgraded to sanitary landfill; and it will increase to 193.5 Gg/year if the existing sanitary landfill is upgraded to integrated waste management facilities. Moreover, Bangkok metropolitan have the highest methane emission (54.83 Gg/year) among all the regions in Thailand. The methane emission forecast of 339 Gg/year by 2020 (based on LandGEM methodology) provides a stimulus to create a comprehensive plan to capture and utilize methane as an energy source.

No abstract