Aerobic pretreatment study for the degradation of lignocellulosic compounds involved in the anaerobic digestion of municipal solid wastes

Abstract

The introduction of anaerobic digestion (AD) for the treatment of the organic matter, such as the organic fraction of municipal solid waste (OFMSW), nowadays is getting more interesting. The main difficulty in the treatment of this waste fraction is the hydrolysis step because of the complexity of organic matter. To avoid these problems, many pretreatments are used in order to increase the solubilization by breaking complex molecules into simple monomers, and to improve the efficiency of AD due to increase the hydrolysis, which is the rate-limiting step. In this project, a biological pretreatment is used to increase the hydrolytic step by using mature compost. The compost fermentative bacteria may break the complex molecules and/or the lignocellulosic materials by means of a fast organic matter solubilization of OFMSW and of bagasse. The results from precomposting the OFMSW indicate that the best conditions of organic matter solubilization were 10% compost and 1 day. Increments of biomethane production of approximately 30% can be achieved in these conditions. A preliminary study of the economic viability of the process shows that these results can be carried out the precomposting on an industrial scale. In the case of bagasse, precomposting mean a decrease in the results so, for this kind of materials with a high soluble fraction composed by very degradable compounds, such as sugars, this pretreatment is not a good option.