Anaerobic digestion of organic matter. Biogas production from energy crop residues (Maize stalks)

• Author(s): Santos, André Manuel Simóes dos
• Date: 2011
• Persistent ID: http://hdl.handle.net/10400.5/4151
• Origin: Repositório da UTL
• Subject(s): renewable energy; anaerobic digestion; maize stalk; biogas; pretreatment
• Document Type: Master thesis
• Language: English
• Advisor(s): Cordovil, Cláudia Marques dos Santos; Duarte, Elizabeth Fernandes de Almeida
• Contributor(s): Repositório da Universidade de Lisboa

Description

Mestrado em Engenharia do Ambiente - Instituto Superior de Agronomia

The agricultural sector is one of the most interesting for effective dissemination of large-scale use of renewable energy, especially anaerobic digestion of feedstock from plant and animal origin. Laboratory-scale experiments were carried out with maize stalks, by apply-ing some pretreatments to enhance its specific biogas yield in anaerobic digestion, due to its methane content. Feedstock were pretreated chemically (different ammonia concentrations), mechanically (particles size reduction) and/or thermally (pressure cooking). The methane percentage in biogas was between 51-72.5% and it was evident that methane yield had the same trend as biogas yield. The highest value of biogas and methane were found on maize stalks just pretreated with 2% NH3 (467.570 LN/kgVS and 280.265 LN/kgVS, respectively) and the lowest were found on maize stalks unwrapped pretreated mechanically (180.81 LN/kgVS and 82.764 LN/kgVS, respectively). The results show that all the pretreatments done were effective in enhancing methane yield, being the best feedstock the one pretreated with 2% NH3 and the best pre-treatment, the one where it was not preformed any other pretreatment. Based on the value of the biogas yield obtained in this experiment, 100.33 GWh of energy can be produced from energetically available amount of maize stalk in Portugal, using 2010 data.