Thesis Abstract

Abstract
This research project aims to investigate and compare the efficiency of ethanol production from two varieties of cassava starch bitter cassava and sweet cassava. Ethanol, a biofuel produced through fermentation of starches or sugars, is a sustainable alternative to fossil fuels. Cassava, a tropical root crop widely cultivated for its starch content, has the potential to be an excellent source for ethanol production due to its high starch content and availability in many regions. The study involves the extraction of starch from both bitter and sweet cassava varieties using standard methods such as washing, peeling, grating, and enzymatic hydrolysis. The extracted starch will then be subjected to fermentation using Saccharomyces cerevisiae, a common ethanol-producing yeast strain. The fermentation process will be optimized by adjusting parameters such as pH, temperature, and fermentation time to enhance ethanol yield. After fermentation, the ethanol will be separated from the fermentation broth through distillation. The ethanol content will be determined using a hydrometer and the quality assessed based on parameters such as alcohol content, specific gravity, and presence of impurities. The efficiency of ethanol production from bitter and sweet cassava starch will be compared based on ethanol yield, purity, and overall process optimization. The research will also investigate the economic feasibility of ethanol production from these two cassava varieties. Cost analysis will be conducted to determine the production cost per liter of ethanol, taking into account factors such as raw material cost, processing cost, and by-product utilization. The potential environmental impact of using cassava starch for ethanol production will also be evaluated, including greenhouse gas emissions reduction and waste management strategies. Overall, this study will contribute valuable insights into the feasibility and efficiency of ethanol production from bitter and sweet cassava starch. The findings will not only advance knowledge in biofuel production but also provide practical information for stakeholders in the ethanol industry, agriculture sector, and environmental policymakers. By exploring the potential of cassava as a sustainable source for ethanol production, this research aims to promote the use of renewable energy sources and contribute to a more sustainable energy future.

Thesis Overview

1.0 INTRODUCTION

The technology for the production of ethanol from starch materials e.g. Cassava involves cooking, liquefaction, saccharification, fermentation and distillation. The basic technology in the process has been well defined but could be improved by introducing systems which require less energy, particularly in the starch conversion and distillation operations (Moorthy and Padmaja, 1990). Application of low-energy requirement systems for the production of ethanol should make it more attractive as liquid fuel (Balagopalan, 1995).

Cassava is one of the richest fermentable substances for the production of ethanol. The fresh roots contain about 30 percent starch and 5 percent sugars, and the dried root contain about 80 percent fermentable substances which are equivalent to rice as a source of ethanol (Moorthy and Padmaja, 1990). In Malaysia and some other countries, many factories are equipped to use cassava roots, starch or molasses (by-product of the sugar industry), the type of product depending on the cost of the raw material (George, 1995). The roots of cassava are washed, crushed into thin pulp and then screened. Saccharification is carried out by adding salphuric acid to the pulp in pressure cookers until total sugars reach 15-17 percent of the content. The pH value is adjusted using sodium carbonate, and the yeast fermentation is allowed for three to four days at suitable temperature for ethanol production (Ray, 1993).

Although the income elasticity of cassava is considered to be low, and in terms of ethanol production, crops like sugar cane enjoy a better competitive position at present, ethanol production in India makes use of cassava as alternate raw material (Balagopalan, 1995). Ethanol production from fresh cassava roots using a low-temperature process is evaluated using a pilot-plant scale (Ray, 1993). The energy saving effect can be analysed. Also the pressurized distillation method could save about 42% of steam consumption against the atmospheric distillation process.

CASSAVA CULTIVATION AND USES
The cassava tuber is widely cultivated in tropical areas. Cassava (Manihot spp) require a temperature of 210C – 350C, rainfall of 150cm – 200cm a well drained rich friable loamy soil. It can also grow in poor soil (Iwena, 1995), cassava tubers are valuable food for man and livestock (Padmaja 1995). It is richer than yam in starch. In India, it is believed to have been cultivated for more than a century and account for 90% feed for livestock. The ability of cassava to supply adequate calories at a lower cost encouraged its maximum use among low-income social groups. It was originally a food security crop used to supplement the rice diet during period of food scarcity, but gradually it has become a subsidiary food even in normal years (George, 1995). Cassava flour is widely used as human food e.g. a bread additive. Some of the fibrous residual material with some remaining starch is used as cattle feed or as a raw material for citric acid production (Shigeru and Maeda 1983).

However, cassava is used in varieties of ways in food, pharmaceuticals, and in manufacturing industries. In food industries which remain the largest consumer of starch and starch product. It is used in confectionaries, canned fruits, jams etc (Moorthy 1995) in large scale industries cassava is the raw material for large scale starch extraction in commercial scale. Sago, a processed food starch marketed as small globules or pearls, manufactured in India is from cassava. It can also be used to make biodegradable plastics the starch extracted can be used in wall board, paper and cloth sizing and adhesive, some of the starch is converted to dextrose and used in fruit canning, yeast production for animal feed, human diet and bakery yeast is made from cassava starch (Somachai 1987).

1.2 OBJECTIVES OF STUDY

The aim of the study is to compare the potentials of two cassava varieties for the production of ethanol.