Bioethanol Production from Locally Growing Algal Biomass: A Promising and Cost-effective Approach

Abstract

Background: Energy production and consumption ratio form the hallmark of the economic prosperity of a country. To keep up with the demand and supply of energy a major switch to biofuels is reasoned but the cost associated with production and the choice of raw material forms two major economical and ethical concerns, especially in the under-developed and developing countries where the food is not sufficiently available to everyone. In this scenario, the use of food sources as raw material becomes unjustified. Purpose: To address these issues, here we made an effort to obtain bioethanol from a non-edible and easily available resource that requires a modest cost of production i.e., a locally available algal bloom. Also, different methods of pre-treatment were employed and scrutinized for their efficacy. These methods of pre-treatment are very cost-effective and easy to administer. Materials and Methods: The algal biomass was pre-treated separately in three ways viz., freeze-thawing, mechanical disruption and rotten wood treatment. The algal cake left out after extraction of lipid content for biodiesel production was also used as a fourth sample. After pre-treatment, the supernatant was collected and estimated for reducing sugar content and allowed to ferment using Saccharomyces cerevisiae. A distillate was obtained and checked for ethanol percentage through gas chromatography. Results: The mechanically disrupted sample yielded the highest percentage of ethanol followed by algal cake, freeze-thawing and rotten wood treatment. Conclusion: Given present food scarcity, the non-edible algae could be a better alternative for bioethanol production as compared to the use of conventional food crops. Through this study, we have found that a better yield can be achieved if the algal biomass is pre-treated via mechanical disruption.