Abstract:
This study describes bioethanol production from
palmyrah (Borassus flabellifer L.) waste using yeast and
optimization of fermentation conditions to increase the yield.
When subjected to different pre-treatment conditions with
various alkaline and acidic solutions, significantly higher
reducing sugar contents were obtained from palmyrah coir dust
with H2SO4 and HNO3 pre-treatments. H2SO4 pre-treatment
at 3%, 5% and 7% concentrations for 15, 30, and 45 minutes
respectively were given to the coir dust, and a significantly
higher quantity of sugar was produced with 3% H2SO4 after
45 minutes of reaction. Among the acids and bases used for the
pre-treatment, H2SO4 is the best hydrolysing agent for coir dust.
When fermentation was done with the coir dust hydrolysed
solution under optimized conditions [30 °C and pH 5.0 with
baker’s yeast (6 × 106 cells mL-1) and incubated in peptone,
yeast extract and nutrient (PYN) medium at 30 °C for 7 days]
, a significantly higher amount of alcohol was produced on the
4th day than the respective non-optimized conditions. Similarly,
molasses and fruit pulp of palmyrah also produced significantly
higher quantities of ethanol individually under similar
optimized conditions used for coir dust on the 6th and 4th day
of fermentation respectively, than the respective non-optimized
conditions. The efficiency of alcohol fermentation by yeast with
palmyrah coir dust acid hydrolysate was 19%. Therefore, coir
dust could also be used as a long-term substrate for bioethanol
production, considering the excess availability of this underutilized
waste material.
