Produção de biodiesel de microalgas cultivadas com vinhaça

Abstract

The growing search for mitigating the consumption of fossil fuels responsible for negative environment impacts caused by the dispersion of their atmospheric pollutants, increased the demand for biofuels in recent years. In this scenario, biodiesel has been gaining prominence, as in addition to being a promising alternative to replace petroleum derivatives, it can be produced from various raw materials, such as microalgae. These microorganisms have been studied for this purpose because they have a considerable lipid content, also they do not require large areas for cultivation. Therefore, the purpose of this work was to carry out the cultivation of the microalgae Chlorella sorokiniana with diluted vinasse, verifying its potential for nutrient remediation and increase of its lipid fraction, to produce a quality biodiesel according to current regulations. Thus, different dilutions of vinasse were studied for the cultivation of Chlorella sorokiniana CTT 7727, being 5, 10 and 15% (v v-1) and N: P: K (20: 5: 20) 1% (v v -1) as a standard for comparison. Cultivation took place for 30 days, with controlled light intensity, constant airflow and 12/12h photoperiod (light/dark). After this step, biomass recovery was carried out following a series of unit operations (coagulation/flocculation/decantation/filtration/drying). From dry biomass, lipid extraction was performed, evaluating the potential of extraction of different solvents together with magnetic stirring or ultrasound. Biodiesel was produced by direct transesterification and analyzed through gas chromatography coupled with a flame ionization detector, enabling the identification and quantification of its fatty acid profile. The results obtained indicated that vinasse with a 10% dilution (v v-1) proved to be the most promising for application as a culture medium for this microalgae species, as it guaranteed a good cell growth rate, as well as a significant biomass productivity and lipid yield. In addition, Chlorella sorokiniana achieved nutrient removal rates above 75% for ammonia, nitrite, nitrate and phosphate, making it an alternative for treating the organic load of vinasse. Considering the biodiesel produced, it fits the regulatory standards of the National Agency for Petroleum, Natural Gas and Biofuels (ANP), demonstrating potential use in certain regions of Brazil, such as Mato Grosso do Sul. , it is concluded that Chlorella sorokiniana cultivated with diluted vinasse is an effective alternative for the production of biodiesel.