Abstract:
Sustaining fossil fuel and the formation of a sizeable environment are trials maintained through
the production of renewable energy as a biofuel. Bioethanol is one of the mainly important
alternative sources of energy, which is produced from the several of cheapest materials includes
starch, lignocellulose, celluloses, and other different waste materials especially agro waste.
Dilute sulphuric acid pretreatment of lignocellulosic material is the main process in ethanol
production due to degradation of a substrate and release a high amount of sugars for anaerobic
fermentation. Therefore, this study was concentrated on the effect dilute sulphuric acid
pretreatment on the production of bioethanol from Phaseolus vulgaris dry seed pods. Each
substrate concentration of both treated with 0.5%(v/v) of dilute sulphuric acid and untreated
was carry out in batch fermentation with 0.5% and 1% of inoculums concentration for 16 days
of fermentation, under a temperature of 28 °C -30 °C and 4.5 pH conditions. Each parameter
(cell biomass, reducing sugars, and amount of bioethanol) was measured on the 4
th, 8th, 12th
,
and 16th day of fermentation times. The result of the study showed that higher quantity of each
parameter was produced in acid pretreated than untreated substrate of the same concentration.
In each of all substrate concentrations, more amount ethanol was yielded in pretreated than
the untreated substrate. The higher amount of cell density (4.26±0.01 mg/ml) was produced in
40 g of treated substrate concentration with 1% of inoculums on the 12th day of the fermentation
period. Increasing fermentation time (up to the 12th) increased the amount of cell biomass up
to maximum and further increment lieder to a reduction of cell biomass. The high quantity of
reducing sugars (8.34±0.06 mg/ml) was also obtained on the 4th day of retention times from
40g of treated substrate concentration with 0.5% of inoculums. However, its measure was
gradually declined by increasing fermentation times. The maximum amount of ethanol
(2.72±0.07%) was produced in pretreated and (2.32±0.08%) from untreated substrate
concentration of 40g inoculated with 1% of inoculums concentration on the 12th day of
fermentation. As a substrate, inoculums concentration and retention times were increasing,
bioethanol production also slightly increased until reach its maximum yields and then becomes
decreased slowly on the 16th day of the fermentation period. Overall, based on the result of this
study it can be concluded that production of ethanol from lignocellulosic agro-waste through
dilute sulfuric acid pretreatment is desirable in terms of high yield.
