Optimisation of process parameters for enhanced biobutanol production from Sargassum wightii hydrolysate

Due to continuous increase in fuel prices, scientists and researchers have shifted their attention towards the use of bio-fuels i.e. the renewable sources of energy. Now days, the third generation algae-based liquid bio-fuels have gained utmost interest among the researchers. Butanol is an algae-based sustainable fuel with different advantages over other alternative biofuels having its low vapour pressure and higher energy density. Different types of macro-algae have been considered in the present study with 55-65% sugars in dry matter of macro-algae. In the present work, brown seaweed (Sargassum wightii) has been considered for bio-butanol production. Subsequently, the acetone-butanol-ethanol (ABE) fermentation has also been carried out using pretreated macroalgae biomass with Clostridium saccharoperbutylacetonicum (ATCC 27022). Different pretreated parameters (acid concentration, temperature, incubation time) for substrate and fermentation parameters (algal hydrolysate concentration, inoculum size and initial pH) for improved biobutanol yield from C. saccharoperbutylacetonicum have been optimised using design of experiments (DoE). The optimised pretreatment conditions (2N H2SO4, temperature 120°C and incubation time 30 min.) and fermentation conditions (70 g/L algal hydrolysate, 15% inoculum size at pH 5.2) have been predicted. Also, the confirmatory experiment with the error of 5-6% has been validated with butanol production of ∼15 g/L having 48% theoretical yield.