دانلود رایگان ترجمه مقاله تولید اتانول از مواد ملاس و پنیری با مخمرها و باکتری ها – Ijcmas 2014

تولید اتانول از ملاس و آب پنیر پرمیت با استفاده از مخمر و نژادهای باکتریایی

Production of Ethanol from Molasses and Whey Permeate Using Yeasts and Bacterial Strains

Abstract

The aim of this work is to study the application of molasses and whey permeate as potential sources of carbon for ethanol production. Also, to study the elimination of agro-industrial wastes and consequently, decrease the cost of ethanol production. Sugar cane molasses and whey permeate were used as carbon sources for ethanol production by yeasts and bacterial strains. Different concentrations of sugar (10, 15, 20 and 25%) were used to study fermentation by two yeast strains (Kluyveromyces marxianus NRRL85.54 and Saccharomyces cerevisiae O-14) and one bacterial strain ( Zymomonas mobilis ATCC 10988). Also, Ethanol production was examined by mixture of molasses and whey permeate using these strains and their mixed culture.bResults clearly indicated that the optimal sugar concentration was 10% sugar for high efficiency of ethanol fermentation by Kluyveromyces marxianus NRRL85.54, Saccharomyces cerevisiae O-14 and Zymomonas mobilis ATCC 10988. Results also showed that best agro-industrial waste for ethanol production is whey permeate with K.marixuanus followed by the mixture of molasses and whey permeate (10% sugar concentration) with mixed culture of three strains then molasses with K.marixuanus.

۱ Introduction

Ethanol production industry is considered one of the important commercial activities for many countries. There is a world-wide search for alternative methods of energy production from renewable sources .The natural energy resources such as fossil fuel, petroleum and coal are being utilized at a rapid rate and these resources have been estimated to over a few years. Therefore, alternative energy sources such as ethanol, methane and hydrogen are being considered. Ethanol has been trusted as an alternate fuel for the future (Smith, 2007). Ethanol is made from a variety of agricultural products &wastes such as grain, molasses, fruit, whey and sulfite waste liquor. Generally, most of the agricultural products mentioned above command higher prices as foods, and others, eg, potatoes, are uneconomical because of their low ethanol yield and high transportation cost. The energy crisis of the early seventies may have generated renewed interest in ethanol fermentation, but its use still depends on the availability and cost of the carbohydrate relative to the availability and cost of ethylene. Sugar and grain prices, like oil prices, have risen dramatically since 1973 (Klein et al , 2004). The many and varied raw materials used in the manufacture of ethanol via fermentation are conveniently classified under three types of agricultural raw materials: sugar, starches, and cellulose materials. Sugars (Sugar cane, sugar beets, molasses, and fruits) can be converted to ethanol directly. Starches (grains, potatoes, root crops) must first be hydrolyzed to fermentable sugars by the action of enzymes from malt or molds. Cellulose (Wood, agricultural residues, waste sulfite liquor from pulp and paper mills) must likewise be converted to sugars generally by the action of mineral acids. Once simple sugars are formed, enzymes from yeast can readily ferment them to ethanol (Dickinson., 1999) . Molasses is waste product of sugar industry and represents a promising raw material for ethanol production. Brazil is pioneer in large scale motor fuel ethanol production through the fermentation of sugar cane molasses by yeasts. Also in India molasses economically are widely used in alcohol industries. (Schweinitzer and Josenhans., 2010). Whey permeate from dairy industry contributes a significant liquid waste for ethanol production while minimizing the environmental problems associated with its treatment and disposal (Staniszewski et al ., 2007; Fonseca, 2008). Several microorganisms have been considered as ethanologenic microbes. The yeast Saccharomyces cerevisiae and Kluyveromyces marxianus and the facultative bacterium Zymomonas mobilis are better candidates for industrial alcohol production (Mohammed et al., 2001; Alfenore et al., 2004). The main aim of the present study to recycling of the agro industrial wastes to reduce the financial cost of the process and the potential of molasses and whey permeate as substrates for ethanol production by yeast and bacterial strains.