Potential Effects of Mechanical Pre-treatments on Methane Yield from Solid Waste Anaerobically Digested

Abstract

The increasing demand of energy supply requires the development of systems of energy production based on the exploitation of renewable energy sources as an alternative to fossil fuels in common use. Through the process of anaerobic digestion it is possible to convert into biogas agricultural biomass, zootechnical waste, sewage sludge and organic fraction of municipal solid waste. After that it is possible to generate energy from biogas through the process of cogeneration. More recent concerns about global warming have stimulated further anaerobic digestion application and the improvement the processes in order to maximize biogas production, which is a renewable and versatile energy source that can be used for heat and electricity production, and as transportation fuel. It is in the interest of operators of anaerobic digestion plants to maximize methane production whilst concomitantly reducing the chemical oxygen demand of the digested material. The pre-treatment of solid waste is regarded as a prerequisite of the anaerobic digestion process to reduce volume and increase methane yield. The aim of the mechanical treatment is the reduction of the size of the biomass and its degree of crystallization, in order to increase the surface area available to enzymatic hydrolysis. This generates an increase on biogas production and a decrease in the time required for the digestion. In this work the link between mechanical pretreatment and the increase of methane yield of some samples of a dedicated crop (triticale) was discussed.