Microalgae in renewable energy: biodiesel and bioplastic production in oil extraction water bioremediation

Abstract

Concerns about climate change, driven by burning fossil fuels and energy and food security, have spurred research, technological development and innovation. Microalgae are being researched as a possible source of third generation biofuels, especially biodiesel, bioethanol and bioplastic. The fact that each microalgal cell does not synthesize stems or other non-producing organs needed for vascular plants makes them efficient in the biological fixation of CO2. It is also known that under some conditions, their lipid content may be higher than oilseeds normally used in biodiesel production. To these attributes of microalgae is added the possibility of being cultivated in desert and coastal areas, do not need drinking water, do not compete with food crops and production is not seasonal and can be harvested all year round. One of the challenges for biodiesel production is the identification of productive strains and the reduction of production costs, currently an order higher than vegetable biodiesel. The use of effluent water as a substitute for synthetic cultivation media needed for microalgae growth can contribute to lower production costs and be associated with effluent bioremediation, making cultivation competitive. Fuel combustion generates about 33.5 billion tons of CO2, but natural processes absorb only half. Oil extraction generates up to five times more effluent water from wells than oil. This produced water (AP) contains organic and inorganic contaminants of difficult remediation and high cost of treatment, as well as salts, among other components. Many microalgae species are potentially capable of growing in wastewater from different sources. This proposal focuses on the sustainable production of renewable energy from microalgal biomass generated during the process of bioremediation of effluent water from petroleum extraction (AP) as a nutrient supply. Native microalgae strains maintained in the labs of the UFBA and UFSCar teams will be evaluated for AP bioremediation. The Bahian group has as main scientific interests the bioprospecting of microorganisms, the production of pilot scale microalgae, associated with environmental monitoring and remediation, as well as biotechnological applications in the area of biofuels, food and biodegradable packaging production. In contrast, the São Paulo group has as main scientific interests the ecophysiology and production of microalgae, biodiversity and microbial processes of aquatic ecosystems, focusing on phytoplankton toxicity assessment and ecotoxicological assessment including different trophic levels, important to broaden the scope of applications. of microalgae biomass fractions. The aim of this project is anchored in the establishment of academic, technical and scientific cooperation to be conducted between the institutions around the common interest of the participants, for the sustainable production of microalgal biofuels via bioprospecting strains and nutrient supply through effluent waters from petroleum extraction. Preliminary results with three strains showed that two bioconverted between 40 and 98% of the AP components (93.13 g/L solids) in cellular and extracellular biomasses containing lipids, polyhydroxyalkanoates and exopolysaccharides with potential application in different industrial sectors. renewable biofuels. Biofuel production, bioremediation of AP effluent water, and the generation of other high value-added products in the concept of a biorefinery would obviously achieve economic viability. (AU)