Abstract
Elements in waste that are disposed of are eventually transferred to either of three destinations : into the atmosphere by landfill gas, into the surface water by leachate, or into a solid waste body within a landfill. Past studies indicate that the ratio of elements that remain in a landfill is rather high even twenty years after disposal. And they also found that these elements diminish from the landfill very slowly even when several centuries are taken into consideration. This implies that many elements remain even after intense reaction phases cease and emission drops to a level where no treatment is required. It must be important to guarantee that these residual elements never cause a negative impact, over long-range period of time. Most of the numerical models for simulating substance behavior in landfills have, up to now, mainly dealt with the degradation process and generation of landfill gas. For long-term prediction, especially with regard to hazardous elements, the model which can deal with the formation of the high molecular organic compounds such as humic substances needs to be developed.
