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Chlorella vulgaris is an eukaryotic microalgae from the Chlorellaceae family which can be cultivated under three different metabolic routes: autotrophic, heterotrophic and mixotrophic –. In the autotrophic metabolic route the microalgae catches the CO2 and solar luminosity, using them as carbon and energy sources through photosynthesis for cell growth. These autotrophic microalgae cultures can be located near industries or CO2 and NOx sources . On the other hand, heterotrophic growth involves higher production costs due to the use of an external carbon source as substrate without CO2 consumption. Therefore, the interest in the use of industrial, agricultural and domestic wastes are prospective alternative substrates for microalgae culture , . And the last metabolic route is the mixotrophic culture. This culture involves the use of inorganic and organic carbon sources , .
This work presents an analysis about the production costs of microalgae C. vulgaris through heterotropic and autotrophic growth. Additionally, C. vulgaris growth was experimentally evaluated using dairy waste as substrate. The total content of lipids, carbohydrates and proteins of the collected and dried C. vulgaris biomass were determined through Methanol-Chloroform method , , Phenol-Sulfuric method  and Kjeldahl digestion method respectively .
With the aim of using some of the molecules produced inside by the microalgae (lipids and carbohydrates from C. vulgaris cake) were evaluate the bioethanol and biodiesel production based on kinetics and yields reported in the literature , , , . The simulation procedure was developed using the commercial software Aspen Plus V8.2 (ASPEN TECHNOLOGY INC). The economic evaluation was performed using the software commercial Aspen Process Economic Analyzer V8.2 (ASPEN TECHNOLOGY INC) taking into account the Colombian context. It was possible to compare 3 cases for the microalgae growth: i) biodiesel and bioethanol production for autotrophic microalgae growth, ii) Biodiesel and bioethanol for heterotrophic growth using a conventional substrate, and iii) Biodiesel and bioethanol production for heterotrophic growth using milk whey as substrate. Finally, considering the share represented by raw materials was probed the sensitivity of microalgae production costs to the substrate source and price. Other important identified issue is related to the microalgae yields which represent the main drawback for profitable biofuels production.
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