Emission risk of environmental pollutant by changing the condition of waste layer after the landfill closure

Abstract

Operation of landfill site can be finished after meeting the closure standard in Japan. In case of the landfill adopted the semi-aerobic landfill type with the leachate collection pit, if the maintenance and operation are stopped, the leachate collection pipe will be submerged and the wastes layer turns out to be the anaerobic condition. This changing condition can happen to increase the risk of methane gas generation and the pollution load of leachate. The waste was collected from the semi-aerobic landfill site which was mainly landfilled by the incombustible waste. This waste was filled in small lysimeters with the semi-aerobic and anaerobic landfill types. It is observed that the influence of changing condition doesn’t make large impact to the landfilled waste. Because, there are the few easily decomposable organic substances and sufficient oxygen exists after the longtime of landfilling. Moreover, it was found that there were almost no risks of increasing the pollutant load for leachate, and generating the hydrogen sulfide and methane gases.