ABSTRACT
This chapter presents the decomposition process in a sanitary landfill and leachate generation mechanism. Many factors interact to produce variable quantity and quality of leachate from landfills. Some factors are: annual precipitation, runoff, infiltration, evaporation, transpiration, freezing, mean ambient temperature, waste composition, waste density, initial moisture content, and depth of the landfill. The decomposition in a sanitary landfill can continue for many years, as long as some organic material is available for bacterial activity. The rate depends on many factors including water movement, pH, temperature, degree of compaction, age of fill, and composition of solid wastes. Water passing through a sanitary landfill carries with it various dissolved and suspended materials. Precipitation includes all water that falls from the atmosphere to the area under consideration. It may occur in a variety of forms including rainfall, snow, hail and sleet. The amount of moisture available for evapotranspiration at a landfill site is affected by the type of soil and vegetation.
