Namhoon Lee*, Tetsuya Kusuda*, Takayuki Shimaoka**, Yasushi Matsufuji** and Masataka Hanashima**

*Dept. of Civil Engineering, Kyushu University
**Dept. of Civil Engineering, Fukuoka University
(8-19-1, Nanakuma, Jonan-ku, Fukuoka 814-01 Japan)

Abstract

Behaviors of pollutants, in particular organic carbon and nitrogen, in solid waste landfill layers and the factors affecting their decomposition, have been studied under semi-aerobic condition using four large scale simulated lysimeters of different packed thickness. This paper presents about 800 days of data through November 1991. Data in this study indicated that the thicker solid waste layers showed less leaching rates in amounts of TOC and T-N. If the layer, however, became as thick as 8 m, no significant decrease in the leaching rate of T-N was observed. This is because nitrogen leached out in the form of NO3-N without smoothly denitrifying at the bottom of the landfill layer. By this, it was suggested that temperature and pH in the landfill layer play important roles not only in microbial activities, but also in dissolutions of organic carbon and nitrogen. Consequently, dissolution and microbial degradation in the landfill layer, resulting from the changes in temperature and pH, tend to occur in turn when leachate moves through the layer vertically. Such behaviors lead to shaping distinctive TOC and T-N concentration distributions.

Key words: solid waste, final disposal, landfill thickness, leachate, pollutants