BIOETHANOL PRODUCTION FROM PELAGIC SARGASSUM WASTE AND ITS POTENTIAL AS A FUEL BLEND ADDITIVE
Utilisation of algal biomass for the production of biofuels has generated a significant interest over the past years. This is due to the high growth rate, productivity, environmental adaptability, products, and multiple benefits obtained from these species. Past studies show the capability of the species to produce bioethanol and other wide range of chemicals through various conversion routes.
A known dominant invasive algae species along the coast of Ghana is Sargassum sp. These drifted algal biomass (Pelagic-Sargassum natans and fluitans) along coastlines, could serve as a valuable supplementary raw material for sustainable bioethanol production, contributing to waste management and energy needs. However, the exploitation and efficient utilisation of it is still not fully identified for the benefit of invaded communities, the country and world at large.
This research study demonstrates the potential of a marine macroalgae waste as a viable feedstock for bioethanol production. Proximate analyses have shown that this pelagic seaweed waste contains substantial carbohydrates. Initial investigations into this biomass also indicated that sulphuric acid hydrolysis produces higher yield of fermentable sugars compared to others. To further enhance the extraction of fermentable sugars from the biomass, hydrolysis conditions of acid concentration, temperature, and time was applied to achieve the highest sugar yield. The kinetics of the hydrolysis process were also studied by varying the temperature and adjusting the duration (time) of the hydrolysis. By considering total biomass conversion into fermentable sugars at optimal conditions, maximum 13.9% of biomass conversion was achieved. Under these conditions, the algal hydrolysate was fermented via the separate hydrolysis and fermentation pathway (SHF) using three Saccharomyces cerevisiae strains of which resulted in a maximum bioethanol yield of 97%, highlighting the potential of this biomass in biofuel production. The activation energy (Ea) and order of the hydrolysis reaction were found to be 41.36 kJ/mol and 1 respectively. The bioethanol derived from Sargassum waste was characterised to establish the following parameters, that is, kinematic viscosity and density. The results indicated that the bioethanol meets the set biofuel property standards. These findings enhance the expanding knowledge base on bioethanol production and present a promising pathway for sustainable energy development, thereby supporting the achievement of Sustainable Development Goal 7.