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

* Department of Environmental and Sanitary Engineering, Faculty of Engineering, Hokkaido University

+ Correspondence should be addressed to Nobutoshi Tanaka:
Faculty of Engineering, Hokkaido University
(Kita 13 Nishi 8, Kita-Ku, Sapporo 060 Japan)

Abstract

In a semi-aerobic landfill where the inlet and outlet of a leachate collection pipe are opened to the atmosphere, when there are any driving forces, atmospheric air flows easily into the pipe. Therefore it will be expected that oxygen can penetrate from the pipe to interior of landfill due to difference of oxygen concentration. The purpose of this study is to present calculation equations of air flow velocity in a single pipe, and to determine the pipe line design factors which are concerned with air flow in the pipe. Main results are as follows: 1) Air velocity in a single pipe can be generated not only by a bit of temperature difference between atmosphere and landfill layer, but also surface wind of landfill site. 2) As a factor for leachate pipe design, temperature difference, wind velocity over surface of landfill site, and height of landfill layer have much more influence upon air flow velocity in the pipe than length and diameter of the pipe. 3) If a short length of the pipe is packed with crushed gravel, air flow velocity reduces drastically. 4) To make the aerobic zone wider in interior landfill layer, it is recommended that the inlet and outlet of pipe are opened to the atmosphere.

Key words: sanitary landfill, semi-aerobic, leachate collection pipe, pressure loss coefficient