BIOETHANOL POTENTIAL FROM WHOLE PARTS OF CASSAVA PLANT IN INDONESIA

Cassava is a promising bioethanol feedstock as all parts of cassava plant including its tuber, stem, leaves, along with processing waste such as peel and bagasse can be used in bioethanol production. However, bioethanol potential from the whole parts of cassava plant is not yet summarized. This research reviewed and calculated the average bioethanol yield from each part of the cassava plant, and calculated bioethanol potential from the whole parts of cassava plant, especially in Indonesia. Fresh cassava tuber, fresh stem, fresh leaves, fresh peel, and dry bagasse are found to have average bioethanol yield of 180 L/ton, 155 L/ton, 75 L/ton, 160 L/ton, and 390 L/ton, respectively. If the whole cassava plant along with its processing waste is utilized for bioethanol production, cassava plants that produce a ton of fresh cassava tuber can yield 400 L bioethanol. With a scenario of total area harvested 700,000 ha and cassava productivity of 22.5 tonnes/ha/year, bioethanol potential from whole cassava plant and its processing waste in Indonesia is 6.3 billion L/year. However, using all the cassava plant for bioethanol production is impractical, considering other utilization of cassava. The bioethanol potential from whole parts of cassava plant after considering other use of plant becomes 2.9 billion L/year. Even when the cassava tuber is used for other utilization, bioethanol from unused cassava stem, leaves, peel, and bagasse is still significant and worth considering. Keywords: bioethanol, cassava plant, wast

Kassava som additiv vid pelletering av biobränsle

In this study, the effects of using fine milled cassava stems as an additive in biofuel pellet production was compared to the effects of refined starch addition. The bulk biomass fuel raw material, to which the additive was added, was a blend of spruce and pine sawdust. An experimental design in the factors cassava/starch content, moisture content and material temperature was used. Measured responses were pellet bulk density, pellet durability, amount of fines, pelletizer motor current, pellet temperature, die temperature and CV for pelletizer motor current (a measure of process stability). Each response was modeled by multiple linear regression (MLR). Good models were found for pellet bulk density, pellet durability and amount of fines, verified by the model performance indicators R2 and Q2. The effects of cassava stem and starch addition showed strong similarities. Both additives have a weak positive effect on pellet bulk density. Both cassava and starch had positive effect on pellet durability, in particular at low moisture contents (MC) ~11 %. At ~14 % the effect of the cassava stems was less pronounced. The highest durability was achieved at low moisture content (11 % MC) when using cassava as an additive. Both additives have a negative effect on amount of fines. Consequently, results from this study show that cassava stems can be used as a substitute to refined starch for increasing fuel pellet durability.I den här studien har effekten av att använda finmalda kassavastammar som bindemedel vid pelletering av biobränsle jämförts med effekten av raffinerad stärkelse. Biomassan var en 50/50 blandning av tall- och gran-spån, till vilken respektive additiv tillsattes, och pelleterades vid olika fukthalter och med olika tillsatser av ånga. Detta för att avgöra om denna raffinerade stärkelse skulle kunna ersättas av de stärkelserika skörderesterna från kassavaodlingar. Egenskaper efter pelletering som jämfördes var: bulkdensitet, hållfasthet, mängden finfraktioner, motorström, pellettemperatur, matristemperatur och CV för motorströmmen (ett mått på motorströmmens jämnhet). Resultatet blev att signifikanta modeller, för hur faktorerna påverkar de uppmätta egenskaperna, kunde byggas för parametrarna; bulkdensitet, hållfasthet och finfraktioner. Resultatindikatorerna R2 och Q2 visar att dessa modeller är tillitsfulla. Vidare visar resultatet på liknande mönster mellan kassava och stärkelse som tillsats. Bulkdensiteten påverkades svagt positivt av båda additiven. Hållfastheten påverkades tydligt av kassavan och stärkelsen där stärkelsen kan ses ha något bättre effekt på fuktiga material (14 % fukthalt) men likvärdig effekt som kassavan på torrare material (11 % fukthalt). Högst hållfasthet kunde återfinnas där kassava tillsattes till ett torrt råmaterial (11 % fukthalt). Båda additiven hade en negativ effekt på andelen finfraktion. Resultaten från studien visade att kassavastammar kan användas som ett substitut till raffinerad stärkelse för att öka hållfastheten på biobränslepellets

Simultaneous saccharification and fermentation of cassava stems

This research evaluates the effects of the inoculum size and enzymatic activity on the concentration of ethanol obtained through the simultaneous saccharification and fermentation of alkali-pretreated cassava stems. Other goals for this study include the determination and validation of the optimal conditions for and the evaluation of the process of ethanol production in a bioreactor. Alkaline-pretreated cassava stems were used as the substrate in a solid to liquid ratio of 1:10; the enzymatic complex Accellerase 1500 and the yeast Ethanol Red were evaluated at two levels at a temperature of 38° C and a pH of 4.0 in an Erlenmeyer flask. The following were evaluated as process controls: simultaneous saccharification and fermentation of non-pretreated stems and separate saccharification and fermentation of pretreated stems. A regression analysis was conducted, and the resulting model was maximized using genetic algorithms. At the optimal conditions identified in an Erlenmeyer flask, the production of ethanol in a 5-liter bioreactor was subsequently evaluated. An experimental concentration of ethanol of 1.88±0.04% v/v (1.99% v/v simulated optimum) was obtained using an inoculum concentration of 1.59 g/L and an enzyme concentration of 13.3 FPU/g. This value was approximately four times the quantity of ethanol produced without pretreatment or by the separate saccharification and fermentation of pretreated cassava stems. The evaluation of the process in the bioreactor yielded an ethanol concentration 20% less than that reached in the Erlenmeyer flaskLa investigación evalúa el efecto del tamaño de inóculo y la actividad enzimática sobre la concentración de etanol obtenido a través de la estrategia de proceso Sacarificación y fermentación simultáneas de tallos de yuca pretratados con álcalis. La determinación y validación de las condiciones óptimas de producción de etanol y la evaluación del proceso en biorreactor fueron también objeto de esta investigación. Tallos de yuca con pretratamiento alcalino fueron utilizados como sustrato en una relación sólido: líquido 1:10; el complejo enzimático Accellerase 1500 y la levadura Ethanol Red fueron evaluados a dos niveles a una temperatura de 38 ° C y pH 4.0 a escala de erlenmeyer. Se evaluaron como controles del proceso: Sacarificación fermentación simultáneas sin pretratamiento de los tallos y Sacarificación fermentación independientes de tallos pretratados. Se realizó un análisis de regresión y el modelo obtenido fue maximizado empleando algoritmos genéticos. A las condiciones óptimas identificadas en erlenmeyer fue evaluada la producción de etanol en biorreactor de 5 litros. Se obtuvo una concentración experimental de etanol de 1.88±0.04 %v/v (1.99 %v/v óptimo simulado) con una concentración de inóculo de 1.59 g/L y una concentración de enzima de 13.3 FPU/g, valor aproximadamente 4 veces mayor a la cantidad de etanol producido sin pretratamiento por sacarificación y fermentación independientes de tallos de yuca pretratados. La evaluación del proceso en biorreactor alcanzo una concentración de etanol 20% inferior a la alcanzada a escala de erlenmeye

Simultaneous saccharification and fermentation of cassava stems

This research evaluates the effects of the inoculum size and enzymatic activity on the concentration of ethanol obtained through the simultaneous saccharifi cation and fermentation of alkali-pretreated cassava stems. Other goals for this study include the determination and validation of the optimal conditions for and the evaluation of the process of ethanol production in a bioreactor. Alkaline-pretreated cassava stems were used as the substrate in a solid to liquid ratio of 1:10; the enzymatic complex Accellerase 1500 and the yeast Ethanol Red were evaluated at two levels at a temperature of 38° C and a pH of 4.0 in an Erlenmeyer fl ask. The following were evaluated as process controls: simultaneous saccharification and fermentation of non-pretreated stems and separate saccharifi cation and fermentation of pretreated stems. A regression analysis was conducted, and the resulting model was maximized using genetic algorithms. At the optimal conditions identified in an Erlenmeyer flask, the production of ethanol in a 5-liter bioreactor was subsequently evaluated. An experimental concentration of ethanol of 1.88±0.04% v/v (1.99% v/v simulated optimum) was obtained using an inoculum concentration of 1.59 g/L and an enzyme concentration of 13.3 FPU/g. This value was approximately four times the quantity of ethanol produced without pretreatment or by the separate saccharification and fermentation of pretreated cassava stems. The evaluation of the process in the bioreactor yielded an ethanol concentration 20% less than that reached in the Erlenmeyer flask