Jessica Hartwig Duarte

Utilization of simulated flue gas containing CO2, SO2, NO and ash for Chlorella fusca cultivation.

Microalgae can use the CO2 from coal power plants in their metabolic pathways. However, these microorganisms must be able to tolerate other residues produced from burning coal. This study evaluated the wastes addition (CO2, SO2, NO and ash) present in the flue gas from a coal power plant on the growth parameters during culture, CO2 biofixation and on the biomass characterization of Chlorella fusca LEB 111. The SO2 and NO injection (until 400ppm) in cultivations did not markedly affect CO2 biofixation by microalga. The best CO2 biofixation efficiency was obtained with 10% CO2, 200ppm SO2 and NO and 40ppm ash (50.0±0.8%, w w(-1)), showing a specific growth rate of 0.18±0.01 d(-1). The C. fusca LEB 111 biomass composition was similar in all experiments with around 19.7% (w w(-1)) carbohydrates, 15.5% (w w(-1)) lipids and 50.2% (w w(-1)) proteins.

Biological CO2 mitigation from coal power plant by Chlorella fusca and Spirulina sp.

CO2 biofixation by microalgae and cyanobacteria is an environmentally sustainable way to mitigate coal burn gas emissions. In this work the microalga Chlorella fusca LEB 111 and the cyanobacteria Spirulina sp. LEB 18 were cultivated using CO2 from coal flue gas as a carbon source. The intermittent flue gas injection in the cultures enable the cells growth and CO2 biofixation by these microorganisms. The Chlorella fusca isolated from a coal power plant could fix 2.6 times more CO2 than Spirulina sp. The maximum daily CO2 from coal flue gas biofixation was obtained with Chlorella fusca (360.12±0.27mgL-1d-1), showing a specific growth rate of 0.17±<0.01d-1. The results demonstrated the Chlorella fusca LEB 111 and Spirulina sp. LEB 18 potential to fix CO2 from coal flue gas, and sequential biomass production with different biotechnological destinations.

Spirulina cultivated under different light emitting diodes: Enhanced cell growth and phycocyanin production

This study evaluated light emitting diodes (LEDs) as a light source in Spirulina sp. LEB 18 cultures in terms of growth parameters and biomass composition. Different photoperiods (partial and integral) and colors (blue, green, red and white) were assessed. Blue, green, red and white LEDs increased biomass productivity and maximum specific growth rate of such cultivations. The maximum biomass concentration (1.77 ± 0.02 g L-1) was obtained when red LEDs in integral light photoperiod were applied to cultivations. The biomass composition showed around 12.8% carbohydrates (w w-1), 57.4% proteins (w w-1) and 12.7% lipids (w w-1). The major fatty acids produced during cultivations were palmitic, linoleic and γ-linolenic. Green LEDs in partial light photoperiod promoted a higher concentration of phycocyanin (126.39 mg gbiomass-1). The potential of LEDs as an energy source in Spirulina sp. LEB 18 cultures was demonstrated by the biomass and bioproducts photostimulation.

Synechococcus nidulans from a thermoelectric coal power plant as a potential CO2 mitigation in culture medium containing flue gas wastes

This study evaluated the intermittent addition of coal flue gas wastes (CO2, SO2, NO and ash) into a Synechococcus nidulans LEB 115 cultivation in terms of growth parameters, CO2 biofixation and biomass characterization. The microalga from a coal thermoelectric plant showed tolerance up to 200ppm SO2 and NO, with a maximum specific growth rate of 0.18±0.03d-1. The addition of thermal coal ash to the cultivation increased the Synechococcus nidulans LEB 115 maximum cell growth by approximately 1.3 times. The best CO2 biofixation efficiency was obtained with 10% CO2, 60ppm SO2, 100ppm NO and 40ppm ash (55.0±3.1%). The biomass compositions in the assays were similar, with approximately 9.8% carbohydrates, 13.5% lipids and 62.7% proteins.

Blue light emitting diodes (LEDs) as an energy source in Chlorella fusca and Synechococcus nidulans cultures

LEDs have narrow wavelength bands, which can influence microalgae biomass. This study pioneers the evaluation of blue LEDs as an energy source in Chlorella fusca and Synechococcus nidulans cultures. Blue LEDs increased the specific growth rate in Synechococcus nidulans LEB 115 cultures by 80% compared to the standard light used in indoor cultivations. Moreover, blue LEDs also induced lipid accumulation in Chlorella fusca LEB 111 cells, yielding concentrations of this bioproduct of up to 23% (ww-1). The chlorophylls and carotenoids were photostimulated proportionally to the LED light intensity. When the intensity of the blue LEDs was increased from 50 to 150μmolm-2s-1, the biomass accumulated up to 4.5 and 2.4 times more chlorophylls and carotenoids, respectively. The potential of blue LEDs as an alternative environmentally friendly light source to stimulate biomass and metabolite production for different purposes was demonstrated.