Abstract

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Optimization of fermentation process for 72 h was carried out to determine the effect of pH (3 – 8), temperature (30°C – 50°C) and agitation rate (200 rpm – 500 rpm) on bioethanol production and microbial count using cassava variety samples. Bioethanol yield and microbial count were highest at pH 6, temperature 35°C and agitation rate of 300 rpm. The bacterial species had highest population counts of 5. 21 x 105 cfu/g at pH 6, 4.62 x 105 cfu/g at temperature 35°C and 4.84 x 105 cfu/g at pH 6, 3.94 x 105 cfu/g at temperature 35 °C for sweet and bitter cassava varieties respectively. The fungal species had highest counts of 5.60 x 104 cfu/g at pH 6, 2.53 x 104 cfu/g at temperature 35°C and 5.20 x 104 cfu/g at pH 6, 2.11 x 104 cfu/g at temperature 35°C for sweet and bitter cassava varieties. Bioethanol yield was 56% and 44% resulting in a significant increase of 75% and 63% for the sweet and bitter cassava varieties respectively. The optimization of the fermentation process yielded maximum bioethanol and also detoxified the cassava processing wastes which are environmental pollutants.

Keywords: Bioethanol, Bitter cassava, Optimized fermentation process, Processing Wastes, Sweet Cassava