Bioethanol Production from Water Hyacinth by Chemical Hydrolysis (Preliminary Study)
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Date
2016-06
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Addis Ababa University
Abstract
Ethiopia, in order to reduce its dependency on imported petroleum fuels which consumes more than70% of the foreign currency earning, climate change issues and to tackle invasive weed problem such as Water hyacinth through integrated management approach of the concept of waste to Energy, a lot of research needs to be conducted.
Bearing this in mind, this study was conducted to conduct preliminary assessment on bioethanol production potential WH by chemical hydrolysis. Water hyacinth was collected from river Awash, the root was cut out and the leaf and stem part were properly washed, dried and chopped for further analyses.
Sample characterization result showed that Water hyacinth has high moisture content and the extractive free WH has 30%, 48% and 5% cellulose hemicellulose and lignin respectively. In this study Water hyacinth was hydrolysed with sulfuric acid (2-5 %v/v), temp (116-130 oC) and hydrolysis time (16-60min) and optimal reducing Sugar obtained was 31.152 g/L at acid concentration 3.97% v/v, Temperature at 129.91 oC and 57.82 minutes reaction time.
In this study, Ethanol yield obtained is extremely low. Ethanol yield ranges from 0.05% to 0.532% from obtained RS of WH hydrolysate with fermentation parameters of temperature 30oC for 72hr and 150 RPM. The highest ethanol yield was not at the optimal value of factors for maximum reducing sugar but at increased acid concentration but at the lower temperature. This may be due to high content of hemicelluloses and at optimal values of factors pentose sugars are high and at increased acid concentration and temperature partial hydrolysis of the cellulose component has occurred to increase the hexoses sugars that are easily fermentable with the given condition.
These results suggest that refinement of the hydrolysis and fermentation process and application of the selected yeast which hydrolyze both hexose and pentose sugars could improve the efficiency of obtaining bioethanol from the water hyacinth.
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Water hyacinth, Bioethanol, hydrolysis, reducing sugar, fermentation