Abstract
Abstract Microalgae are unicellular organisms capable of photosynthesis, turning sunlight and carbon dioxide (CO2) into rich biomass, precisely because of this definition in recent years, various sectors have been targeting the ability to reduce CO2 emissions and the capacity of simultaneously synthesize biomass which can later be used to produce bio-fuels. In respect to the capturing and utilization of CO2 emitted by different industries (cement, generation of electric energy, cellulose and ethanol production by fermentation of sugars) for the cultivation of microalgae destined to the production of bio-fuels, for example, biodiesel, ethanol or bio-oil. However, this research was developed in the Green Technologies Laboratory - Greentec / EQ / UFRJ, which focussed on the monitoring of CO2 consumption in microalgae Monoraphidium sp. cultivated in closed-window type photobioreactor, as well as, the characterization of the microalgal biomass produced in relation to the total lipid content (TL), convertible lipids into biodiesel (CLB), carbohydrates and proteins.The overall procedure involved the evaluation of the following parameters: injection of CO2, temperature (°C), lighting (μE m-2 s-1), pH, cell density (cells ml-1) and dry biomass. From the results of this study, it was observed that at the beginning of the culture (day 0) 0.79 g of CO2 were consumed per each gram of biomass produced. On the last day (12), 0.3 g of CO2 were consumed per gram of culture. On the sixth day of cultivation, the consumption of CO2 per gram of biomass increased, resulting in a CO2 consumption of 0.61 g. The best result was obtained on the second day of cultivation, when for each gram of biomass produced approximately 1.2 grams of CO2 were consumed. The biomass Monoraphidium sp. produced, contained 17,37 ± 3,27% of total lipid content, approximately 8.36 ± 2.69% of convertible lipids into biodiesel, 32% ± 3.37 of carbohydrates and 34.26% ± 0.41 of protein. The analysis performed by -GC-MS Gas chromatography showed the following composition of saturated fatty acids (SAFAs) mainly the C16:0 (palmitic), as in monounsaturated acids (MUFAs), in high quantity C18:1 (oleic) and polyunsaturated acids (PUFAs) mainly represented by C18:2 (Linoleic) and C18:3 (linolenic).
Highlights
Many factors, some of which are related to industrial development and diverse agricultural practices, are responsible for large quantities of carbon monoxide and dioxide in the atmosphere
The strain or standard culture used in the study was stored under controlled conditions in a screw-top test tube containing ASM-1medium kept in an incubator BOD 411D, with temperature controlled at 23 ° C and illuminated by four (4) 8 watts (W) fluorescent lamps providing a light intensity of 500 μE m-2s-1 (Fig. 1B)
The acid pretreatment procedure was performed as follows: an amount corresponding to 400 mg wet biomass dry weight was weighed on an analytical balance; 5 mL of HCl 2 M was added to the biomass and homogenized with the aid of vortex model MS3 basic IKA; the tube was placed in a thermostated bath at 80 °C for 1h; centrifuged at 2500 rpm for 15 minutes to separate the biomass acidic residue; the acid residue was removed and discarded in an appropriate vial
Summary
Some of which are related to industrial development and diverse agricultural practices (forest burning), are responsible for large quantities of carbon monoxide and dioxide in the atmosphere. In Brazil, during the United Nations (UN) Summit on Sustainable Development in September 2015, President Dilma Rousseff had already announced that the country plans to reduce by 37% the emissions that cause the greenhouse effect until the year2025, compared to levels recorded in 2005, reaching 43% by 2030. In this context, this research has developed aims in capitalizing on the CO2 removed in the biogas purification process, from its bio-fixation in microalgae cultivation for the production of renewable hydrocarbons. The resulting so-called ester fuels have proven suitable for blending with diesel stocks, up to 30% without affecting engine performance (Brindley C, et al 2002)
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