Second Generation Bioethanol Production: Green Alternative Energy for Future Energy Crisis

Abstract

Emerging environmental pollution and depleting fossil fuel resources issues are creating a
requirement for more environmentally friendly alternative renewable fuels. In that case bioethanol
has gathered much attention as a fuel additive and fuel enhancer. In the current study, corncob and
paper waste were used as lignocellulosic biomass and followed the simultaneous saccharification and
fermentation via bacterial pathways to produce second generation bioethanol. Both biomasses were
pretreated initially using mechanical and chemical pretreatments and they were hydrolysed by two
bacterial strains; Bacillus sp. and Norcadiopsis sp. and fermented by Achromobacter sp. which were
previously isolated. The bioethanol production was followed by hydrolysing of biomass by Bacillus
sp. and Norcadiopsis sp. for 72 hours at 37° C and then the fermentation was done using the bacterium
Achromobacter sp. for 72 hours at 37° C. Detecting gas trapped in Durham tubes and Solid Phase
Micro Extraction coupled with GCMS were used to screen and quantify the ethanol production
respectively. The highest ethanol percentage (v/v) was obtained from alkaline pretreated paper waste
hydrolysed by the Bacillus sp. (0.734±0.154%) and the lowest ethanol percentage (v/v) was obtained
from alkaline pretreated corncob hydrolysed by the Norcadiopsis sp. (0.155±0.154%). Acid
pretreated corncobs, alkaline pretreated corncobs, and acid pretreated paper waste which was
hydrolysed by Bacillus sp. and fermented by Achromobacter sp. produced ethanol percentages (v/v)
of 0.726±0.154%, 0.564±0.154%, and 0.657±0.154% respectively. Acid pretreated corncobs, acid
pretreated paper waste, and alkaline pretreated paper waste which was hydrolysed by Norcadiopsis
sp. and fermented by Achromobacter sp. produced ethanol percentages (v/v) of 0.587±0.154%,
0.599±0.154%, and 0.627±0.154% respectively. Thus, the results of the study revealed that both
corncobs and paper waste have high potential for bioethanol production, and paper waste is the best
feedstock for second-generation bioethanol production among used biomasses.

Keywords: Bioethanol production, Lignocellulosic biomass, Corncobs, Paper waste