Numerical modeling of landfill processes: Complexity versus practicality

Abstract

Bioreactor landfills are emerging as a sustainable means of municipal solid waste (MSW) management due to enhanced rates of waste decomposition which leads to early waste stabilization in landfills along with other short-term and long-term benefits. Currently, no well-established procedures or design guidelines exist to design and operate such landfills safely and effectively. This largely stems from the fact that there is no clear understanding of the fundamental processes and their interdependencies that influences the behavior of the waste and consequently the overall performance of a bioreactor landfill. Mathematical modeling of the major landfill processes (hydraulic, mechanical, biochemical, thermal) and their interrelated behavior using numerical methods is a useful tool in understanding the landfill performance and has been carried out ever since the late 1980s. Several researchers have developed numerical models to simulate the behavior of MSW in landfills with varying mathematical complexity. However, most of these models don’t find their application in the current state of practice, although many of the simpler models are increasingly welcomed by landfill owners and design professionals. This paper briefly summarizes the important concerns regarding the development of numerical models for modeling of landfill processes and their applicability in practice. Further, the key technical challenges that need to be addressed while developing a numerical model are discussed. The purpose of this paper is to have the landfill modelers embrace the need for a balance between the complexity and practical applicability of the model for the design and operation of bioreactor landfills.