Browsing by Author "Otenio, Marcelo Henrique"
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- Biofuel recovery from microalgae biomass grown in dairy wastewater treated with activated sludge: the next step in sustainable productionPublication . Mendonca, Henrique Vieira de; Otenio, Marcelo Henrique; Marchão, Leonilde; Lomeu, Alice; Souza, Denise Salvador de; Reis, AlbertoABSTRACT: Microalgae biofuel could be the next step in avoiding the excessive use of fossil fuels and reducing negative impacts on the environment. In the present study, two species of microalgae (Scenedesmus obliquus and Chlorella vulgaris) were used for biomass production, grown in dairy wastewater treated by activated sludge systems. The photobioreactors were operated in batch and in continuous mode. The dry biomass produced was in the range of 2.30 to 3.10 g L-1. The highest volumetric yields for lipids and carbohydrates were 0.068 and 0.114 g L-1 day(-1). Maximum CO2 biofixation (750 mg L-1 day(-1)) was obtained in continuous mode. The maximum values for lipids (21%) and carbohydrates (39%) were recorded in the batch process with species Scenedesmus obliquus. In all of the experiments, the Linolenic acid concentration (C18:3) was greater than 12%, achieving satisfactory oxidative stability and good quality. Projected biofuel production could vary between 4,863,708 kg and 9,246,456 kg year(-1) if all the dairy wastewater produced in Brazil were used for this purpose. Two hectares would be needed to produce 24,99 x 10(9) L year(-1) of microalgae bioethanol, a far lower value than used in cultivating sugar cane. If all dairy wastewater generated annually in Brazil were used to produce microalgae biomass, it would be possible to obtain approximately 30,609 to 53,647 barrels of biodiesel per year. These data show that only by using dairy wastewater would biofuels be produced to replace 17% to 40% of the fossil fuels currently used in Brazil.
- Microalgae-mediated bioremediation and valorization of cattle wastewater previously digested in a hybrid anaerobic reactor using a photobioreactor: Comparison between batch and continuous operationPublication . Vieira de Mendonça, Henrique; Ometto, Jean Pierre H. Balbaud; Otenio, Marcelo Henrique; Reis, Alberto; Marques, Isabel PaulaABSTRACT: Scenedesmus obliquus (ACOI 204/07) microalgae were cultivated in cattle wastewater in vertical alveolar flat panel photobioreactors, operated in batch and continuous mode, after previous digestion in a hybrid anaerobic reactor. In batch operation, removal efficiencies ranges of 65 to 70% of COD, 98 to 99% of NH4+ and 69 to 77.5% of PO4-3 after 12 days were recorded. The corresponding figures for continuous flow were from 57 to 61% of COD, 94 to 96% of NH4+ and 65 to 70% of PO4-3 with mean hidraulic retention time of 12 days. Higher rates of CO2 fixation (327-547 mg L-1 d(-1)) and higher biomass volumetric productivity (213-358 mg L-1 d(-1)) were obtained in batch mode. This microalgae-mediated process can be considered promising for bioremediation and valorization of effluents produced by cattle breeding yielding a protein-rich microalgal biomass that could be eventually used as cattle feed.
- Valorization and Bioremediation of Digestate from Anaerobic Co-Digestion of Giant Reed (Arundo donax L.) and Cattle Wastewater Using MicroalgaePublication . Henrique, Guilherme; Renato, Natalia; Borges, Alisson; Martins, Marcio Arêdes; Reis, Alberto; Otenio, Marcelo HenriqueABSTRACT: Anaerobic digestion followed by microalgal cultivation is considered a promising renewable alternative for the production of biomethane with reduced effluent generation, thus lowering the environmental impact. In this arrangement, in addition to generating energy, the microalgae act by potentiating the refinement of the effluents generated via anaerobic digestion (digestates). In this study, the microalga Tetradesmus obliquus was cultivated in photobioreactors with the final digestate resulting from the co-digestion of Arundo donax L. plant biomass and cattle wastewater. The biotechnological route used was efficient, and the biogas production ranged from 50.20 to 94.69 mL gVS-1. The first-order kinetic model with variable dependence (FOMT) provided the best fit for the biogas production data. In the microalgal post-treatment, the removal values ranged from 81.5 to 93.8% for the chemical oxygen demand, 92.0 to 95.3% for NH4+-N, and 41.7 to 83.3% for PO43- after 26 days. The macromolecular composition of the algal biomass reached lipid contents ranging from 33.4 to 42.7%. Thus, the proposed process mediated by microalgae can be considered promising for the bioremediation and recovery of effluents produced by agriculture through the use of microalgal biomass for bioproduct production.