Sangchul Park*, Tetsuya Kusuda*, Takayuki Shimaoka** and Masataka Hanashima**

* Department of Civil Engineering, Faculty of Engineering, Kyushu University
** Department of Civil Engineering, Faculty of Engineering, Fukuoka University

+ Correspondence should be addressed to Tetsuya Kusuda:
Department of Civil Engineering, Faculty of Engineering, Kyushu University
(6-10-1 Hakozaki, Higashi-ku, Fukuoka 812-81 Japan)

Abstract

The purpose of this study is to make a mathematical model for conversion processes of organic carbon and nitrogens in landfilled layers under semi-aerobic conditions and also to estimate better conditions for landfill. This model is a 1-D three phase model which is composed of several processes including elusion of pollutants from solid waste, microbial decomposition, convection and dispersion in the liquid phase, exchange of liquid in the mobile and stagnant liquid zones, transport between liquid and gas phases, and convection and diffusion in the gas phase. Microbial decompositions consist of aerobic, acid forming and methane producing processes. Microbe growth rates are expressed as a function of both temperature calculated by heat balance and pH in terms of alkalinity. Numerical simulation results indicate that the elusion of organic matter in the upper layer, aerobic decomposition of organic matter in the middle, and aerobic decomposition, nitrification and denitrification in the lower are predominant. Aerobic zones, especially the bottom layer of the semi-aerobic landfill, play a significant role in the purification of leachate.

Key words: solid waste, semi-aerobic landfill, pollutant conversion, modeling, simulation, organic carbon, organic nitrogen