Aline Meireles dos Santos

Heterotrophic Cultivation of Cyanobacteria: Study of Effect of Exogenous Sources of Organic Carbon, Absolute Amount of Nutrients, and Stirring Speed on Biomass and Lipid Productivity

The production of bioproducts from cyanobacteria with techno-economic feasibility is a challenge to these biotechnological processes. The choice of low-cost raw materials is of great importance for the overall economy of bioprocesses, as they represent a significant percentage in the final cost of the product. The objective of this work was to study the operational parameters of cultivation (exogenous sources of organic carbon and absolute amount of nutrients) to optimize productivity in bioproducts by Aphanothece microscopica Nägeli, for further evaluation of stirring speed. The experiments were performed in a bubble column bioreactor, operating at 30°C, pH of 7.6, C/N ratio of 20, 100 mg/L of inoculum, continuous aeration of 1 volume of air per volume of culture per minute (VVM), and absence of light. The results indicate that absolute amounts of 5,000/250 using cassava starch resulted in improved system performance, reaching biomass productivity of 36.66 mg/L/h in parallel with lipid productivity of 6.65 mg/L/h. Finally, experiments with variation in stirring speed indicate that 200 rpm resulted in better average rate of substrate consumption (44.01 mg/L/h), in parallel to biomass productivity of 39.27 mg/L/h. However, the increase of stirring speed had a negative effect on lipid productivity of the process. The technological route developed indicates potential to production of biomass and bulk oil, as a result of the capacity of cyanobacteria to adapt their metabolism in varying culture conditions, which provides opportunities to modify, control, and thereby maximize the formation of targeted compounds.

Microalgal Biorefineries for Bioenergy Production: Can We Move from Concept to Industrial Reality?

Biorefineries are commercial facilities that transform raw materials into commodities of considerable interest to the world bioeconomy. In addition, biorefineries have the potential to achieve favorable environmental characteristics, such as minimal greenhouse gas (GHG) emissions and a lower water footprint, compared to homologous fossil fuels. However, for this concept to become efficient and viable, the use of potentially abundant and specific renewable biological feedstocks should be considered, such as microalgae biomass and other generated products. However, there is an emerging need to consolidate industrial plants that are not only affected by market fluctuations but also aim to transform biological materials into industrially usable products. Thus, for a microalgae biorefinery to compete with the resilient oil refineries in the future, process integration in the supply chain is a promising engineering approach, associating all the components from the cultivation to obtain multiple products that are economically and environmentally sustainable. Therefore, the objective of this review is to compile issues related to microalgal biorefineries applied to bioenergy and biofuel production.

Cassava processing wastewater as a platform for third generation biodiesel production

This study aimed to evaluate third generation biodiesel production by microalgae Phormidium autumnale using cassava processing wastewater as a platform. Experiments were performed in a heterotrophic bubble column bioreactor. The study focused on the evaluation of the bioreactor (batch and fed-batch) of different operational modes and the analysis of biofuel quality. Results indicate that fed-batch cultivations improved system performance, elevating biomass and oil productions to 12.0 g L−1 and 1.19 g L−1, respectively. The composition of this oil is predominantly saturated (60 %) and monounsaturated (39 %), resulting in a biodiesel that complys with U.S., European and Brazilian standards. The technological route developed indicates potential for sustainable production of bulk oil and biodiesel, through the minimization of water and chemical demands required to support such a process.