Aproveitamento do concentrado da dessalinização via osmose inversa para desenvolvimento de Chlorella sp e Chlorella vulgaris visando a produção de biodiesel.

Abstract

Fossil fuels to be an inexhaustible source became a worldwide concern because of the need to meet excessive demand both in industrial and transportation. A major concern with current fossil fuels is the harmful/hazardous environmental effect it causes by the generation of gases that cause global overheating warming. These reasons this concern have led man looking for new sources of renewable energy. In this regard, oilseeds have become the main source of biofuels, though it has been under heavy criticism mainly because of the excessive use of arable land that would compromise the generation production of food. Another source of renewable energy that does not present this difficulty is biofuel from microalgae. The (microalgae) need adequate nutrients for development. These nutrients can be from the preparation of a synthetic or supplied form other sources, such as the use of domestic wastewater, brackish waters and other waste. This study examined the feasibility of (growing) microalgae Chlorella sp and Chlorella vulgaris in a modified culture medium with addition of the concentrate product from the process of desalination of brackish water via the reverse osmosis in order to evaluate the potential production of the biodiesel microalgae studied. This study was conducted in two stages: the first step carried out studies in a bench scale, developed in the LABDES/UFCG and BIOTEC/UFSC laboratories. In this step, two strains of Chlorella sp (TU1 and TU3) and a strain of Chlorella vulgaris were grown in culture medium Bold's Basal Medium (BMB) and there growth assessed. The culture was carried out at 26 C under illumination 5klux and a photoperiod of 12 hours with continuous stirring. Chlorella vulgaris showed higher productivity growth, reaching a maximum cell growth of 5.9xl07eeLmL_1e with lipid content of 8.56%. In the fatty acid profile analyzed by gas chromatography,34.68% of the fatty acids were saturated. The studies followed with culture media modification by addition of the concentration. The track showed a better cell growth yield and with lipid was added to the culture medium 10-25% of the concentrate. 25% of the concentrate to in the culture medium corresponded to a conductivity of 1.622u.S.cm"' and approximately 1054.30 mg.L"1 SDT. A cell density of 4.7 x 107cel.mL"' was obtained, which had a lipid content of 9.76%, 40.57% saturated fatty acids, the levels of carbohydrates and proteins remained unchanged with respect to culture in 100% of BBM. The separation of the cell type by means of flocculation was inefficient due to the great loss of biomass. The separation process by microfiltration membranes showed better efficiency. The second stage of this work was developed in raceway ponds of4000L, Urucu located in the community, district of the ray tracing-PB. The results obtained in these ponds were not satisfactory. The lipids contents were 2.88%, there was also a decrease in protein and carbohydrates concentrations, mainly due to variations in temperature and luminance. The culture in the open proved highly complex to operate in local weather conditions which hampered cell development. However, under conditions of a laboratory scale photobioreactors, the use of the concentrate was viable because it provided excellent cell growth while maintaining high values of carbohydrates and proteins, except for fatty acids, thus showing the possibility of minimizing the environmental impacts caused by concentrated.