Characterization and qualification of torrefied biomasses properties during fungal deterioration for energetic purposes

• Ano de defesa: 2020
• Autor(a) principal: Faria, Bruno de Freitas Homem de
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: eng
• Instituição de defesa: Universidade Federal de Viçosa
• Palavras-chave em Português: Biocombustíveis; Fungos decompositores; Lignocelulose; Espectroscopia de infravermelho próximo; Tecnologia e Utilização de Produtos Florestais
• Link de acesso: https://locus.ufv.br//handle/123456789/28043

Lignocellulosic biomasses are a reliable alternative to fossil fuels to produce more environmentally friendly energy, mainly due to their renewable and sustainable characteristics, and their worldwide availability. The torrefaction process can be a good way to improve specific characteristics of biomass to achieve better storage conditions and for energetic use. The aim of this study was to evaluate the impact of torrefaction on the storage of different biomasses residues, simulated by fungal deterioration, for energetic purposes. The impact of leaching and fungal deterioration on the chemical and energy properties of raw and torrefied biomasses for energy conversion was thus evaluated. Finally, near infrared spectra were collected to build PLS-DA and PLS models to be able to better understand the fungal deterioration of biomasses. Coffee husk, sugarcane bagasse, pine residues and eucalyptus residues were torrefied at 290 °C in a screw type reactor, for 5, 7.5, 10, 15 or 20 min. The effects of feedstock type and torrefaction process parameter (holding time) on their energy characteristics were investigated. Raw and torrefied biomasses were then submitted successively to leaching and to white rot (Trametes versicolor) and brown rot (Coniophora puteana) fungi to simulate storage conditions. Mass loss after the leaching step, moisture content and mass loss due to fungal deterioration after 2, 4, 8, 12, and 16 weeks were recorded. Variations in carbon content and high heating value were observed during the fungal deterioration of raw and torrefied biomass. Brown rot fungus was more virulent than white rot fungus in pine, leading to mass losses close to 35% for pine torrefied for 15 minutes. For sugarcane bagasse torrefied for 7.5 and 10 minutes, the mass loss during fungal deterioration was less than 10% for all evaluation weeks, being much lower than the mass loss observed for raw sugarcane at 16 weeks (approximately 60%). PLS models for predicting the calorific value of biomasses showed good predictive capacity with RMSEP of 0.1968 and Rp of 98.17%. PLS-DA classification models are reliable to differentiate types of biomass and then, through specific models, identify the most active decay fungus in raw and torrefied biomasses as well as the stage of deterioration at which the biomasses are. PLS developed models appeared to be efficient to predict the high heating value of raw and torrefied biomasses according to their fungal deterioration stages. Torrefaction of eucalyptus, pine, sugarcane bagasse and coffee husk seems to be a viable method to eliminate some of the disadvantages of these raw biomasses as it significantly improves energy content and prevents absorption of moisture during storage. In addition, coffee husk appears to be a very promising biomass for energy conversion by torrefaction process, due to its good energetic increase. Keywords: Biofuel. Fungi decay. Lignocellulose. Near-infrared spectroscopy.