Nobutoshi Tanaka*, Toshihiko Matsuto* and Youngkyu Kim**

* Department of Environmental and Sanitary Eng. Faculty of Eng., Hokkaido Univ.
** Department of Environmental Eng. Faculty of Eng., Jeongbuk Univ.

+ Correspondence should be addressed to Nobutoshi Tanaka:
(Kita 13, Nishi 8, Kita-ku, Sapporo 060 Japan)

Abstract

A theoretical method is presented for numerical calculation of air flow in the leachate collection pipe network in semi-aerobic landfills. It is shown that the presented method is also effective on a complex network. The method is applied to an assumed typical landfill site and the following are obtained. 1) Maximum air temperature increase between inlet and outlet in the pipe network is a good index for comprehensively estimating the influence of thermal factors such as atmospheric temperature, temperature of pipe wall and heat transfer coefficient between the pipe wall and air in pipe. 2) The depth of the landfill has little effect on the inlet velocity of air flow. 3) The maximum of the inlet air flow rate is attained when the diameter of the main pipe is more than 1m and enough air cannot be supplied into a leachate collection pipe network when the diameter is less than 0.4m. 4) The less diameter of branch pipe there is, the less velocity of inlet air flow is attained. Enough air cannot be supplied when the branch diameter is less than 0.15m. 5) Enough air can be supplied even if the distance between each branch pipe is 50m.

Key words: semi-aerobic landfills, air flow, leachate collection pipe network, design of leachate pipe