Joji Fukuyama* and Junji Masuda*

* Osaka City Institute of Public Health and Environmental Sciences

+ Correspondence should be addressed to Joji Fukuyama:
(8-34 Tohjohcho Tennohji-ku Osaka 543 Japan)

Abstract

The issue of gas emission at a landfill site is deeply related with environmental pollution around the site and safe utilization of the land. For countermeasuring of the gas, it is necessary to accurately make clear the condition of the gas emission and forecast the future change in gas generation. First, this report describes the desirable methods for the survey of generating gas at landfill sites in detail. Next, the characteristics of gas generation at the landfill site are reviewed, indicating the results of our landfill gas surveys for 10 years or more. At a coastal landfill site with many gas-drawing wells, methane content in the gas was about 17-45% and hydrogen sulfide was detected at a high concentration such as 50ppm or more under landfill of solid waste, and for a few years after the landfill. At this site where 10 million tons of solid waste had been filled, the methane generation rate per ton of waste is calculated to be 5-6L/day and total amounts of methane gas generation was about 20,000-30,000m3/day for a few years before and after the completion of landfill. When 6 years had passed after landfill completion, methane generation drops to 1/5th value of the peak period and concentration of hydrogen sulfide was mostly 0.5ppm or less. The combustion method of the gas is generally used as a countermeasure of landfill gas and performs well for deodorization. The above knowledge and information is thought to be very useful in the planning of land utilization.

Key words: landfill, methane, gas generation, hydrogen sulfide, countermeasure