Publication: A STRATEGY FOR COMBINED ENZYME AND BIOGAS PRODUCTION FROM WHEAT STRAW IN A BIOREFINERY
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Date
2017
Authors
ALBORNOZ PASTÉN, SANDRA MACARENA
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Abstract
Debido a diversos problemas medioambientales, se necesita maximizar el valor económico de los residuos lignocelulósicos (LCW) dentro de un concepto de biorefinería. La digestión anaeróbia (AD) puede usar los LCW para producir biogás. Además, la aplicación de un tratamiento fúngico antes de la AD puede mejorar el proceso y producir enzimas de alto valor como lacasa (Lac) y manganeso peroxidasa (MnP). Sin embargo, tiempos de tratamiento largos y alta pérdida de carbohidratos, son algunas de las variables que afectan la digestión anaerobia en gran medida. Para el tratamiento fúngico, se utilizaron los hongos de pudrición blanca Trametes versicolor, Pleurotus eryngii y Pleurotus ostreatus, sobre paja de trigo previamente descontaminada en dos tamaños de partícula (1.4 a 2.36 mm y 0.5 a 1 mm) y durante tres tiempos de tratamiento (0, 15 y 30 días). Los mejores resultados se obtuvieron para 15 días de tratamiento con P. Ostreatus ya que se obtuvieron mayores niveles de azúcares reductores, actividad enzimática para lacasa (382 U / L), pérdida de lignina y parámetros de Gompertz referidos a la producción de biogás (producción máxima de 302.4 ±10.7 NmL y una tasa máxima de producción de biogás de 12.2±1.8 d-1), utilizando un tamaño de partícula menor (0.5 a 1 mm). Estos resultados mostraron que es posible obtener enzimas de alto valor como la lacasa y mejorar la producción de biogás dentro del mismo proceso. Las futuras investigaciones deben centrarse en la evaluación de otras variables tales como la adición de inductores o incluso tiempos de pretratamiento más cortos.
This research proposes a new biorefinery concept in which lignocellulosic waste is valorized through a sequential process of fungal treatment and an anaerobic digestion process.In the fungal treatment stage, the production of high-value enzymes, such as laccase, was studied; in the anaerobic digestion stage, biogas was produced as a renewable energy source.Wheat straw in two different size ranges (0.5 to 1 mm and 1.4 to 2.36 mm) was subjected to fungal treatment during 30 d to quantify the enzyme production. The degree of enzyme production of three white rot fungi was compared: Trametes versicolor, Pleurotus eryngii and Pleurotus ostreatus. Then, the residual gas production was quantified after 0, 15 and 30 d of fungal treatment.The best process combination was obtained after 15 d of treatment with P. ostreatus, in which higher reducing sugar release, laccase activity (382 U/L), lignin loss and modified Gompertz parameters (a maximum production of 302.4 ±10.7 NmL/gVS and a maximum biogas production rate of 12.2±1.8 d-1) were obtained for this treatment with smaller particle sizes.These results showed that it is possible to obtain high-value enzymes, such as laccase, and enhanced biogas production within the same process by approximately 30 %. Further investigations should focus on evaluating other operational variables, such as the addition of inducers and reduced fungal treatment times.
This research proposes a new biorefinery concept in which lignocellulosic waste is valorized through a sequential process of fungal treatment and an anaerobic digestion process.In the fungal treatment stage, the production of high-value enzymes, such as laccase, was studied; in the anaerobic digestion stage, biogas was produced as a renewable energy source.Wheat straw in two different size ranges (0.5 to 1 mm and 1.4 to 2.36 mm) was subjected to fungal treatment during 30 d to quantify the enzyme production. The degree of enzyme production of three white rot fungi was compared: Trametes versicolor, Pleurotus eryngii and Pleurotus ostreatus. Then, the residual gas production was quantified after 0, 15 and 30 d of fungal treatment.The best process combination was obtained after 15 d of treatment with P. ostreatus, in which higher reducing sugar release, laccase activity (382 U/L), lignin loss and modified Gompertz parameters (a maximum production of 302.4 ±10.7 NmL/gVS and a maximum biogas production rate of 12.2±1.8 d-1) were obtained for this treatment with smaller particle sizes.These results showed that it is possible to obtain high-value enzymes, such as laccase, and enhanced biogas production within the same process by approximately 30 %. Further investigations should focus on evaluating other operational variables, such as the addition of inducers and reduced fungal treatment times.
Description
Catalogado desde la version PDF de la tesis.
Keywords
DIGESTION ANAEROBIA , PRODUCCION DE BIOGAS , RESIDUOS LIGNOCELULOSICOS