Methane production in landfill: a fractal approach

MERAZ, R.L.; ARANDA, C.; VIDALES, A M; DOMINGUEZ, A.

Landfill Research Focus

Nova Science Publishers, Inc.

Lugar: New York; Año: 2008; p. 311 - 336

Landfill appears as a very convenient choice to get rid of municipal solid waste, while providing energy due to methane generated through anaerobic fermentation. Nonetheless, without capture and treatment landfill gas is considered an important source of atmospheric methane. The control and use of this gas require knowledge of both, current yield and long-term accumulative production. These values are usually calculated with mathematical expressions that consider 100% conversion. Nevertheless, fermentation in landfills is erratic and spatially heterogeneous. This chapter presents a comprehensive fractal approach to model the main transport processes involved in the methane production from landfill. The idea behind this model is that methane production kinetics is limited by the diffusion of hydrolyzed substrate in a heterogeneous solid-phase towards discrete areas, where methanogenesis occurs. We study and discuss the basic concepts of mass diffusion in fractal environments, and their application to methane production in landfill problem. The predictions from this fractal approach are contrasted with those arising from two conventional equations broadly employed in the industrial work. In the fractal approach, the spectral dimension appears for pondering the tricky mass transfer in the fill. Spectral dimension values are obtained by fitting published field and laboratory data by means of the fractal approach, these values fall in the interval , screening the hindered mass transport in landfill. Finally, the upshot on landfill methane production after the exertion of an organic waste reclaim program (e.g. food-yard waste composting or paper waste recycling) is virtually studied under the perspective of the fractal approach herein developed, with the aim to evaluate the pertinence of the application of a given organic waste reclaim program in order to diminish the release of methane from landfill to atmosphere.