ABSTRACT
The principles of decomposition in landfills are reviewed to establish bases for quantifying the concentrations of individual constituents that are expected in leachate. Indications of the expected values and ranges of concentrations are provided. The trends in landfilling are examined, and implications for the contaminating life span of landfills are presented. The need to view leachate treatment as a long-term commitment and the resulting interest in cost avoidance are major determining factors in reaching a decision on leachate management strategy. The paper describes the typical concentrations within leachate and provides indications of circumstances when deviations from these concentrations may occur. Wetlands provide an important opportunity to contribute in this activity, but the magnitudes of the concentrations and the implications of temporal variabilities in leachate quantities and qualities must be understood, before incorporating a flexible design in the establishment of constructed wetlands.
