Computer simulation of leachate quality by recirculation in a sanitary landfill bioreactor.

Sanitary Landfills are the most widely used method of solid waste disposal around the world. Modern sanitary landfills are designed with impervious liners, and leachate collection, removal, and treatment systems to minimize the potential for groundwater contamination. Leachate recycle through the landfill is an effective method of leachate treatment, and to enhance solid waste stabilization. A mathematical model is developed to simulate the release of contaminants from solid wastes, and their movement into the percolating liquid. Two differential equations are used that express the mass balance of the contaminants in the percolating water and those in the solid wastes. These simultaneous linear differential equations are solved numerically using a fourth-order Runge-Kutta algorithm with many physical and process parameters. The model results are used to estimate the active life of landfill with and without leachate recirculation. Such information is valuable in the operation, maintenance, and closure plan of a sanitary landfill.