Biological carbon capture and utilization (BCCU): An integrated process for O2 production and reduced CO2 emission/ Captura e utilização biológica de carbono (BCCU): um processo integrado para produção de O2 e emissão reduzida de CO2

The objective of this work was to evaluate the O2 production and CO2 emission in an integrated process. The experiments were performed in a bubble column photobioreactor with a volume of 2 L, luminous intensity of 15 µmol/m2/s, aeration of 1 VVM with air injection enriched with 15% carbon dioxide. The photobioreactor was integrated into a bio-combustion furnace designed on a laboratory scale, where the emissions were evaluated. The fuel used was petroleum coke. The experimental conditions in the were: initial coke mass 1.0 g, total combustion time of 20 min, and airflow 1.0 L/min. A gas chromatograph to determine greenhouse gas emission was used. The results showed a CO2 capture and O2 production in the photobioreactor of 0.46 and 0.40 kg/m³, respectively. Furthermore, the CO2 emissions in the furnace were 0.71 kg/m³. In this sense, the photobioreactor demonstrated the ability to capture carbon and produce bioproducts, and when integrated into a bio-combustion process, presented the potential to mitigate greenhouse gas

Environmental performance for microalgae cultivation commercial systems: sustainability metrics and indicators / Desempenho ambiental para sistemas comerciais de cultivo de microalgas: métricas e indicadores de sustentabilidade

In this study, we evaluated metrics and sustainability indicators for cultivation commercial systems based on microalgae. Cultivation systems as a raceway pond, tubular photobioreactor, flat plate photobioreactor, and fermenter were evaluated under a standard functional unit of 1 m³. These cultivation systems were estimated by midpoint indicators through the nine impact categories and later submitted to the normalization phase. Among the results found, three impact categories were shown to be more expressive to contribute to environmental impacts for the four cultivation systems, which are ecotoxicity potential, energy resource, and global warming potential. The best environmental performance was identified for raceway pond, although the worst-case scenario for the water footprint category was identified. Besides, in a comparative analysis between closed systems, fermenters showed better environmental indicators, followed by tubular and flat plate photobioreactors. In this way, the life cycle assessment allowed to highlight the hot points of the process, identifying the energy requirements as the critical points of the whole performance of the cultivation systems. Finally, regardless of the impacts associated with different cultivation configurations, it is important to note that the choice of the system will be directly associated with the target product to be produced. Therefore, the results found about the environmental performance of cultivation systems can serve as basic information to reduce the global environmental impacts of microalgae-based processes and bioproducts.

Extraction by supercritical fluids of value-added compounds from microalgae grown in photobioreactors simulating different climatic conditions

Resumen del trabajo presentado al 17th European Meeting on Supercritical Fluids y al 7th European Meeting on High Pressure Technology, celebrados en Ciudad Real (España) del 8 al 11 de abril de 2019.[Introduction]: Microalgae cultivation is strongly dependent on the daylight availability. Under natural climatic conditions, the light intensity, the photoperiod and the temperature play a key role in increasing the performance of microalgal-based processes. Globally, the market for microalgae-based products has gained a lot of attention in recent years because of the potential of these microorganisms to produce high-value bioproducts, like pigments, omega-3 fatty acids, proteins and carbohydrates which may be used in several food, pharma and cosmetic applications. Although there is such a market, the advance of microalgal biotechnology to a medium-sized market requires studies on the optimization of the industrial scale, due to the high costs for the extraction of biocompounds of interest. In this regard, there is a need to combine appropriate, selective, costeffective, and environmentally friendly extraction procedures with the legal requirements regarding the use of food-grade solvents and processes. Recently, there has been an increasing interest in the use of supercritical fluid extraction (SFE) with carbon dioxide (CO2) as a solvent. Carbon dioxide is an ideal solvent for the extraction of natural products because it is non-toxic, non-explosive, readily available and easy to remove from extracted products. In this sense, the objective of this work was to evaluate the influence of climatic conditions on the production of high-value biocompounds and their selective extraction from the biomass through a compressed fluids’ platform; the microalga Scenedesmus obliquus has been employed as case study.[Results and discussion]: The biomass of Scenedesmus obliquus was grown under different conditions in photobioreactors, simulating diverse climatic conditions in Brazil (tropical, subtropical, tropical Atlantic and equatorial) in four extreme regions (Boa Vista-RR, Rio Grande-RS, João Pessoa-PB and Rio Branco-AC). The different biomasses have been subjected to sequential extractions in order to achieve extracts enriched in target biomolecules. A compressed fluids’ platform has been employed considering different steps such as supercritical fuid extraction with pure carbon dioxide, SFE with carbon dioxide plus a polar modifier (ethanol), gas expanded liquids and pressurized liquid extraction. Final extracts’ composition has been determined by high performance liquid chromatography coupled to evaporative light-scattering detector (HPLC-ELSD) and HPLC coupled to diode array and mass spectrometry detectors (HPLC-DAD-MS/MS).[Conclusions]: Significant variation of climates by geographic location in the production of high-value bioproducts is an important tool in the planning and implementation of future microalgae-based cropping projects based on available climatic resources anywhere in the world

Environmental assessment of the integrated bio-combustion process: A life cycle energy balance / Avaliação ambiental do processo integrado de bio-combustão: balanço energético do ciclo de vida

The aim of the present study was to evaluate the life cycle energy balance of the integrated bio-combustion process. The life cycle analysis tool was applied to assess the environmental performance of the system. The experiments were performed in a bubble column photobioreactor with a volume of 2L, photon flux density of 150 µmol/m²/s, continuous aeration of 1VVM, and injection air-enriched with 15% of CO2. The photobioreactor exhaust gases were integrated into the bio-combustion furnace, which was designed on a lab-scale. The operational conditions were: initial coke mass of 1g, total combustion reaction time of 20 min, and airflow rate of 1 L/min. The energy balance was determined by equating of the energy produced by the required energy, followed by the net energy ratio. The results obtained showed a net energy ratio for the integrated process of 0.69, indicating an energy efficiency improvement close to 70%. Thus, the system has the potential to boost the sustainability of industrial facilities.