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Contextualization: Currently, interest in the production of microalgae has increased due to the different uses of microalgal biomass in some industrial sectors, in addition to being used in the mitigation of greenhouse gases thanks to its high capacity for CO2 capture. Knowledge gap: Being part of the Paris Agreement in 2015, Colombia is committed to reduce its greenhouse gases emissions by 20%, to contribute to the goal set for 2050, for this reason, it must adopt research and action plans focused on this objective. Purpose: the purpose of this study was to evaluate the effect of CO2 induction at different concentrations on the growth kinetics of Chlorella Vulgaris CV_2714A and Scenedesmus Obliquus SOB_001 in a laboratory scale photobioreactor system in a volume of 3.8 L of culture medium (NPK solution + micronutrients). Methodology: The tests were carried out in photoperiods with 12 hours of light and 12 hours of darkness for 5 consecutive days. The completely randomized experimental design whose sources of variation were microalgae species and CO2 dosage (0.2, 6.5 and 12.8 L. day-1) with artificial lighting by a 4400-lumen fluorescent lamp. The cellular concentration was estimated by means of the numerical approximation in the "Neubauer" chamber with the methodology used by Darki et al. (2017), in addition to growth rate and cell doubling time in days according to Andersen, (2005). The data were submitted to analysis of variance and Tukey's mean tests (p<0.05). Results and conclusions: The results in the different tests showed a higher cell concentration in C. vulgaris compared to S. obliquus. Regarding CO2 supply, the 2 species obtained a significantly greater response (p<0.05) at the dose of 6.5 L. day-1, reaching a cellular concentration of 2.59 x 107 cel.ml-1 and 4.62 x 106 cel.ml-1, respectively. These results allow us to conclude that the cultivation of these microalgae associated with the dose of CO2 can favor their rapid growth and biomass production, while also contributing to other studies on the reduction of greenhouse gases. [ABSTRACT FROM AUTHOR]

Introduction: Due to the decrease of oil, an alternative energy source such as microalgae biomass is planted to obtain lipids and then biodiesel. Objective: to evaluate the influence of CO2 and the initial concentration of Chlorella vulgaris on lipid production on a laboratory scale. Material and methods: four microalgae growth tests were developed, with CO2 concentrations (0-3%; 3-6%; 6-9%; 9-12%) as a carbon source for biomass production. Start with a cell density of 8.01x106; 1.34x107; 1.74x107 and 1.58x107 cells/mL. The growth parameters were determined in the research group (Ángel, 2012), as a culture medium Foliagro® was used, from the 21 W red light bulbs for cycles of 12/12 hours light/dark, pH 7.5 and a temperature of 24 °C ± 2.5 °C. Results: CO2 concentrations were determined to be between 0-3% and 6-9%, with a cellular production of 3.65x107 cells/mL, satisfactory for the two intervals. The yield of the lipids produced was 61.83%, for a CO2 concentration between 0-3% and 54.49% for a CO2 concentration between 6-9%. Conclusions: for the test 1, the iodine index was 67.91 and the saponification index 107.99; for the test 3 the first was 63.12, and second was 132.63, the parameters that indicate that the lipids produced are useful for the production of biodiesel. [ABSTRACT FROM AUTHOR]

In this paper, fuelethanol production from Chlorella vulgariscake wasevaluated by experimental and conceptual design techniques.Enzymatic hydrolysis and fermentation with Saccharomyces cerevisiaewas performed to quantify the reducing sugars and ethanol from microalgaecake. Extractive distillation and molecular sieves were evaluatedas alternative technologies for the dehydration of ethanol. The massand energy balances were solved using the Aspen Plus software. Thetotal ethanol production costs were evaluated using the Aspen ProcessEconomic Analyzer software, and the Waste Reduction algorithm (WAR)was used to calculate the environmental impacts. Additionally, theeffect of energy integration was included in the economic analysisand environmental assessment. The yields obtained for reducing sugarsand ethanol were 0.55 and 0.17 g per g of cake, respectively. Theglobal yield of ethanol was 211.9 L per tonne of cake, and the totalproduction cost was 0.76 and 0.91 USD per liter using molecular sievesand extractive distillation, respectively. The most promising technologyto produce ethanol from microalgae cake was dehydration by molecularsieves with full energy integration. For this technology, the productioncost was 0.76 USD per liter, which resulted in an economic marginof 19.15%. From the environmental point of view, the potential environmentalimpact was 0.84 PEI/kg products. Additionally, bioethanol from microalgaewas shown to be less harmful than bioethanol from corn and sugar cane. [ABSTRACT FROM AUTHOR]

In South America, Colombia is known as an important oil-producing country. However, the environmental impact of crude oil industry has not been studied deeply and few studies have been carried out for evaluating responses of algae and its adaptation under specific conditions. Enzymatic and physiological effects in Chlorella vulgaris and its potential for bioremediation after exposure to produced water (PW) were assessed using different PW concentrations (0, 25, 50, 75 and 100%) and crude oil. Variables such as cell density, growth rate (μ), percentage of growth inhibition (% I), chlorophyll a and b and cell diameter were evaluated during 5 days. Furthermore, enzymatic biomarkers such as superoxide dismutase (SOD) and catalase (CAT) were also measured. Results showed that the treatment with 100% PW had the highest cell density and μ; similarly, 25% PW treatment had a similar behaviour, being these two treatments with the highest growth. A dose-dependent response was seen for chlorophyll a and b and cell diameter, showing significant differences between treatments and the control. Different levels of SOD and CAT were observed in algae exposed to PW. At 24 h, an increase in SOD and CAT activity was observed, probably due to effects caused by xenobiotics. After 72 h, a decrease in the activity of both enzymes was observed. The results evidenced that C. vulgaris can adapt easily to PW, showing an increase on its growth and stabilisation in its antioxidant activity. Additionally, cell diameter results and decrease of hydrocarbons and phenols show the potential of these algae to degrade xenobiotics from PW. [ABSTRACT FROM AUTHOR]