Potencial das microalgas Clorella vulgaris e Dunaliella tertiolecta BUTCHER para produção de biocombustíveis e biorremediação de efluente doméstico e rejeito de dessalinização.

Abstract

The desalination of brackish groundwater is, in many locations in the semi-arid region, the only solution for water supply. However, the reverse osmosis membrane desalination process produces a polluting waste that is difficult to treat. Another challenge of the same dimension concerns the post-treatment of the effluent produced by the treatment of domestic sewage in an anaerobic filter, in order for it to adapt to the rules for dumping in water bodies. Thus, the bioremediation of wastewater, using microalgae, appears as a complementary treatment option for these effluents. In addition, the biomass resulting from the cultivation of microalgae has a high concentration of lipids, raw material for the production of biodiesel. Thus, the present research aimed to evaluate and optimize the bioremediation potential and biofuel production of the microalgae species Chlorella vulgaris and Dunaliella tertiolecta in a medium composed of wastewater. The study was conducted under laboratory conditions, in Campina Grande - PB, using the Central Composite Rotational Design (DCCR). To control the cultivation conditions, three factors were chosen: Photoperiod, pH and Effluent Proportion (PDE). To measure the bioremediation capacity, the chosen variables were Chemical Oxygen Demand (COD), Total Phosphorus (PT), Salinity and Electrical Conductivity. The variables used to measure crop development were Productivity and Growth Rate. Subsequently, the lipid content of the species was also obtained. The results showed a maximum COD removal of 81.25% (D. tertiolecta) and 100% PT removal (C. vulgaris), a maximum growth rate and productivity of 0.0509 h-1 (C. vulgaris) and 0.1662 g. L-1.dia-1 (D. tertiolecta), respectively. The models were mostly validated. Finally, the lipid contents of the species biomass were established, for the optimized cultivation conditions, of 42.56 and 13.92% for Dunaliella tertiolecta and Chlorella vulgaris, respectively. It is concluded that the use of alternative means for microalgae cultures, aiming at bioremediation and biofuel production is something viable.