Application of fuzzy logic in modern landfills

Abstract

Landfill is by far the dominant and most economical method for the disposal of solid waste worldwide. The landfill ecosystem involves several physical, chemical, and biological processes that take place simultaneously. The complexity of the landfill processes as well as the uncertainty of solid waste characteristics have led to the implementation of unconventional techniques in modeling the system. In fact, no conventional model could be successfully developed for such a nonlinear ill-defined system because it is practically impossible to isolate the individual effect of its variables and satisfactorily identify its behaviour. Recently, knowledge-based techniques, such as fuzzy logic, became widely used to model complex systems based on qualitative knowledge about their behaviour. This paper presents an implementation of fuzzy logic to solve a serious operational problem in modern landfills. A typical sanitary landfill evolves through consecutive operational phases which are hard to distinguish and characterize. The identification of these phases is vital because each phase has different requirements that have to be met in order to assure safe and smooth transition from one phase to another. A fuzzy logic controller was developed to identify the operational phase of a landfill at a given time based on certain quantitative characteristics of the leachate generated and biogas produced.