Modeling unsteady state leachate flow in a landfill using finite difference and boundary element methods.
Item
-
Title
-
Modeling unsteady state leachate flow in a landfill using finite difference and boundary element methods.
-
Identifier
-
AAI9304631
-
identifier
-
9304631
-
Creator
-
Ahmed, Shabbir.
-
Contributor
-
Adviser: Reza M. Khanbilvardi
-
Date
-
1992
-
Language
-
English
-
Publisher
-
City University of New York.
-
Subject
-
Engineering, Civil | Engineering, Mechanical | Engineering, Sanitary and Municipal
-
Abstract
-
The physical processes involving leachate flow in a solid waste landfill are described by the unsaturated flow through the refuse to the saturated leachate mound at the bottom of a landfill. The moisture-flow in the unsaturated zone helps build up the saturated leachate mound at the bottom of a landfill. The moisture content in the unsaturated zone is obtained by solving the two-dimensional unsaturated moisture-flow equation using numerical techniques. A two-dimensional unsteady state Flow Investigation for Landfill Leachate (FILL) model, based on the implicit finite-difference technique, has been developed to describe the leachate flow process in a landfill.;To obtain accuracy and efficiency in numerical modeling, it is important to investigate the numerical solution techniques suitable to solve the governing equations. Accuracy and efficiency of the boundary integral method over the finite-difference method has been investigated. Two approaches, direct Green's function and perturbation Green's function formulations have been developed to solve the unsaturated flow problem. Direct Green's function and perturbation Green's function boundary integral solutions are found to be more accurate than both the Gauss-Seidel iteration and Gauss-Jordan elimination method of finite-difference solution.;The efficiency of the boundary integral formulation for the computation of the moisture-flux is an advantage that is useful to estimate leachate accretion in a landfill. A close agreement of the internal fluxes with the exact solution shows the ability of the boundary integral methods to compute accurate recharge from the unsaturated zone to the saturated leachate mound.;To gain confidence in the finite-difference scheme for the saturated leachate flow equation, two numerical methods, Gauss-Seidel iteration and Gauss-Jordan elimination, are used to solve the finite-difference expressions. Satisfactory performance of the two methods are observed in computing leachate mound-head for leachate accretion from the unsaturated zone. The finite-difference FILL model representing the unsaturated-saturated flow has been applied to an example landfill section to demonstrate the effectiveness of the model in providing information such as evapotranspiration, surface runoff, recharge, and leachate flow rates in both the lateral and vertical directions.
-
Type
-
dissertation
-
Source
-
PQT Legacy CUNY.xlsx
-
degree
-
Ph.D.
