Chemical absorption and CO2 biofixation via the cultivation of Spirulina in semicontinuous mode with nutrient recycle

Abstract

The chemical absorption of carbon dioxide (CO2) is a technique used for the mitigation of the greenhouse effect. However, this process consumes high amounts of energy to regenerate the absorbent and to separate the CO2. CO2 removal by microalgae can be obtained via the photosynthesis process. The objective of this study was to investigate the cultivation and the macromolecules production by Spirulina sp. LEB 18 with the addition of monoethanolamine (MEA) and CO2. In the cultivation with MEA, were obtained higher results of specific growth rate, biomass productivity, CO2 biofixation, CO2 use efficiency, and lower generation time. Besides this, the carbohydrate concentration obtained at the end of this assay was approximately 96.0% higher than the control assay. Therefore, Spirulina can be produced using medium recycle and the addition of MEA, thereby promoting the reduction of CO2 emissions and showing potential for areas that require higher concentrations of carbohydrates, such as in bioethanol production.

Bioprocess strategies for enhancing biomolecules productivity in Chlorella fusca LEB 111 using CO2 a carbon source

“…The all gas flow rates were measured by rotameters (Cole Parmer). To increase the residence time of the carbon source in the medium, the stirring of the assays was stopped 1 min before and 1 min after the addition of CO 2 to the culture . Two control assays were carried out with stirring by atmospheric air and: (a) standard BG‐11 medium; (b) BG‐11 medium without Na 2 CO 3 , in this one the CO 2 of atmospheric air (0.03% vol/vol CO 2 –0.08 ml CO2 ml medium −1 days −1 ) was the unique carbon source.…”

“…The use of microalgae is a biological strategy, and it is considered a promising alternative to other strategies because of its high photosynthetic efficiency during the bioconversion of CO 2 to biomass compared with terrestrial plants . In addition, the resulting biomass is primarily composed of proteins, carbohydrates, and lipids, which can be used in bioproducts and biofuels such as biodiesel and bioethanol …”

Cell-nanoparticle assembly fabricated for CO2 capture and in situ carbon conversion

“…For example, in the first cycle, CO 2 fixation capacity was 71 mmol CO 2 /g dry cell in 24 h; in the second cycle, 68 mmol CO 2 /g dry cell was obtained in 24 h; but in the fifth cycle, 52 mmol CO 2 /g dry cell was obtained in 44 h. For several algal CO 2 sequestration processes in photobioreactors, CO 2 fixation yield was about 12 mmol CO 2 /g cells per day by Spirulina sp. [13], or 43 mmol CO 2 /g cells per day by Chlorella sp. [12].…”

“…With the addition of monoethanolamine (MEA) and CO 2 in the cultivation process of Spirulina sp. LEB 18, algae can be produced using medium recycle and the addition of MEA, thereby promoting the reduction of CO 2 emissions [13]. Beside photosynthesis microalgae, some nonphotosynthetic carbon-fixation microorganism can selectively capture CO 2 without light irradiation, and convert CO 2 to some useful platform chemicals such as ethanol and organic acids [14], among which, succinic acid is a four-carbon diacid (C 4 H 6 O 4 ), and is a precursor in the chemical synthesis of various commodities in food, chemical, agricultural, and pharmaceutical industries [15].…”

“…Choi et al [21] believed that the CO 2 biofixation by microalgae could be improved if the amount of dissolved gas in the liquid was increased beyond the natural balance of the algal culture. The use of MEA in microalgae cultures can increase the CO 2 fixation activity [13,22]. However, one of the major limitations to the implementation of the CO 2 capture technology by amine is the high-energy consumption and cytotoxicity [23].…”