ABSTRACT

This study was aimed at producing an alternative energy source(bioethanol)from sulphuric acid

and alkaline hydrogen peroxide treated sugarcane bagasse and rice stalkemploying simultaneous

saccharification and fermentation process using co-cultures of isolated and characterized strains

of Aspergillus niger and Saccharomyces cerevisiae. The proximate composition of the substrates

was determine. The composition of sugarcane bagasse and rice stalk treated with sulphuric acid

were determined to be (6.30% ash), (3.05% protein), (84.15% carbohydrates) and (4.75 ash),

(5.25 protein), (80.55 carbohydrates) respectively, while that of sugarcane bagasse and rice stalk

treated with alkaline peroxide were (7.95% ash), (1.75% protein), (83.20% carbohydrates) and

(5.10% ash), (7.00% protein), (77.65% carbohydrates) respectively.The characterization scheme

used were cultural, morphological and microscopic for A.nigerand cultural, microscopic and

physiological for S. cerevisiae. Garden Soil(GS02) isolateof A. nigerthat possess 6.2mm and

17.1mmdiameter of zone of starch and cellulose hydrolysis respectively and palm wine (PW02)

isolateof S. cerevisiaethat tolerates up to 15% ethanol where selected for the production. At

optimal fermentation conditions of 35ºC temperature, 5.0 pH, 4% substrate concentration,

300rpm agitation rate and 4 days fermentation period, a maximum of 6.20g/100ml and 5.06

g/100ml of ethanol were obtained from sulphuric acid-treated sugarcane bagasse and rice stalk

respectively.After determining the quantity of the ethanol produced using specific gravity

method, qualitative analysis using FTIR-Spectrophotometrywhich showed the absorbance peaks

of the ethanol functional groups of all the ethanol samples produced and the functional groups

had their absorption peaks within their normal ranges of 3100-3600cm-1, 2800-3000cm-1 and

1600-1675cm-1 for hydroxyl functional group, saturated and unsaturated parts of the compound

respectively.

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1.0                                                       INTRODUCTION

1.1                                           Background to the Study

Increase in world‘s energy demand and the progressive depletion of oil reserves motivate the

search for alternative energy resources, especially for those derived from renewable materials

such as biomass (Saxenaet al., 2009). Global concern about climate change and the consequent

need to diminish greenhouse gas emissions have encouraged the use of bioethanol as a gasoline

replacement or additive (Balatet al., 2008). This is because cellulosic ethanol and ethanol

produced from other biomass resources have the potential to cut greenhouse gas emissions by

86% (Wang et al., 2007).

The current estimated sugarcane production of Nigeria as at 2008 was put over 1.4m tones. This

figure represents the combined production of both industrial and domestic consumption.

Sugarcane for domestic consumption is produced more than that produced for industrial use.

Thus, chewing cane accounts for between 55 – 65% of the total cane production, the bulk of

whichis consumed raw for the sweetness of it‘s juice but some of it is processed into a variety of

products such as sugar, molasses, bagasse, sweets and left-over leaves/stalks (Busar and Misari,

2007). Although there are vast potential for the commercial production of this crop, its

processing industry did not come into existence in Nigeria until the early 1960s (Abdullahi,

2000).

Aspergillus nigercan be used in the industry in so many ways such as production of citric and

gluconic acids (Ojumu, 2003).It can also be used in biotechnology industry for production of

magnetic isotope-containing variants of biological molecules (Kansoet al., 1999).Furthermore,

Solomon et al.,(1999) reported that A. nigercan be cultured for extraction of enzyme glucose

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oxidase which can be used in design of glucose biosensors due to its high affinity for beta-D

glucose.

Saccharomyces cerevisiaeis a species of yeast whose cells are round to ovoid, 5–10 μm in

diameter. It reproduces by a process known as budding. It is perhaps the most useful yeast,

having been instrumental in baking, and brewing since ancient times. It is believed to have been

originally isolated from the skin of grapes (one can see the yeast as a component of the thin

white film on the skin to winemaking of some dark-colour fruits such as plums; it exists among

the waxes of the cuticle). It is one of the most intensively studied eukaryoticmodel organism in

molecular and cell biology, just like Escherichia coli. It is the microorganism behind the most

common types of fermentation (Feldmannet al.,2010).

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