PRODUCCIÓN DE BIOETANOL CON CÉLULAS INMOVILIZADAS

Abstract

Nowadays, the efficiency in the ethanol production has been increased of stable way, since it is considered like a product of high added value. Nevertheless, the use of the ethanol like fuel additive could only be considered if the costs in the ethanol production are reduced; for this reason, the work proposal is related to the use of mixed cultures with cells free and immobilized of Zymomonas mobilis and Saccharomyces cerevisiae in calcium alginate. The realized acid hydrolysis with sulfuric acid to 5% of cassava sample (Manihot esculenta Crantz) allowed obtaining the greater fermentable sugar concentration maltose and glucose (74.9 g/L and 125.6 g/L, respectively). For enzymatic hydrolysis, the sample of which produced major fermentable sugar concentration maltose and glucose was the cassava (Manihot esculenta Crantz) with 75.9 g/L and 48.6 g/L respectively. The optimal conditions of growth of Saccharomyces cerevisiae and Zymomonas mobilis were determined, using enzymatic hydrolysate of cassava like carbon source, which was of 30-40 °C and pH of 5 and 30-40 °C and pH of 8.5, respectively. In addition, the optimal conditions of ethanol production of Saccharomyces cerevisiae and Zymomonas mobilis were determined, which was of 40 °C and pHs of 5-8.5 and 40 °C and pH of 8.5, respectively. In order to carry out the fermentation with free cells in mixed culture it was used in a shaken reactor of 2 L, with agitation of 100 rpm, 40 °C and initial pH of 8.5; it was inoculated first with Zymomonas mobilis and 12 h later Saccharomyces cerevisiae, obtaining a ethanol production of 13.08 g/L, and a yield of 0.5773 (gprod/gsust). The fermentation with immobilized cells in mixed culture was carried out in a shaken reactor of 0.5 L, with agitation of approximately 100 rpm, initial pH of 8.5 and 40 °C of temperature; it was inoculated first with Zymomonas mobilis and 8 h later Saccharomyces cerevisiae, obtaining a ethanol production of 8.42 g/L and a yield of 0.4097 (gprod/gsust). With these results we can say that immobilization had a positive effect in the biomass production, nevertheless the ethanol production is fallen in a 35 %. For that reason he is recommendable to prove new systems of culture using free, immobilized and co-immobilized cells of S. cerevisiae and Z. mobilis.