The Use of Semi-Mechanized Landfills for Small to Medium-Sized Cities in Developing Countries

摘要

Purpose: Open dumping is the most common practice for the disposal of urban solid wastes in the developing regions of Africa, Asia and Latin America. Although sanitary landfill design and operation has traditionally focused on large cities, 52 percent of the world urban population lives in cities with fewer than 500,000 inhabitants, and cities fewer than 100,000 in population are notably underserved in terms of government support for waste disposal. These thousands of smaller cities worldwide cannot afford to operate a sanitary landfill in the way it is proposed for large cities, where heavy equipment is used to spread and compact the waste in daily cells, and then to excavate, transport and apply daily cover. This paper presents an alternative approach for small communities, known as the semi-mechanized trench method. Methods: In this semi-mechanized method of landfilling a hydraulic excavator is used for one to three days to dig a trench that will last at least a month before it is filled with deposited waste. Trucks can easily unload their wastes into the trench, and the wastes compact naturally due to their weight and decomposition in a few months, after which they are refilled and covered. The exposed surface area is minimal since only the top surface of the wastes is exposed, the remainder being covered by the sides and bottom of the trench. The surplus material from trench excavation can be valorized for use as engineering fill elsewhere. Results: A detailed case study from Villanueva, Honduras shows that this method has been used successfully for fifteen years in a municipality of approximately 45,000 persons at a cost of US$6.00 per ton with a land requirement of 0.2 m2/person-year. Main Conclusions: The semi-mechanized trench method can be used worldwide in small cities as a technically appropriate and sustainable solution to solid waste disposal.