Cultivo da microalga Chlorella vulgaris em efluente industrial, como meio alternativo, para produção de biomassa visando obtenção de energia verde

Abstract

The production of microalgal biomass has been extensively studied due to its biotechnological applications, mainly due to its ability to accumulate bioproducts such as lipids, carbohydrates, proteins, pigments and others. The biomass of the green microalgae Chlorella vulgaris can be used mainly in the bioremediation of effluents and in the synthesis of compounds with high added value, such as biofuels. Furthermore, culture media are sought after as an alternative to synthetic media that guarantee similar or even greater growth in order to minimize cultivation costs. Therefore, the objective of this work is to quantitatively analyze the final biomass production of the microalgae Chlorella vulgaris in an alternative medium, industrial effluent, aiming at the production of green energy. The experiment was carried out in 20L polyethylene reactors with a useful volume of 10L, with constant aeration and a 12/12 hour light photoperiod, differing in the cultivation medium used. The experimental setup consisted of two treatments (MC and EI) in triplicate, where MC is the cultivation of microalgae in standard control medium, f/2 GUILLARD, and EI is the cultivation in an alternative medium, industrial effluent. The growth of microalgae was monitored for 10 days using an optical density spectrophotometer (HACH) and cell counting in a Neubauer chamber. Effluent treatment was monitored using a multiparameter probe (HANNA). Biomass was obtained through chemical flocculation with NaOH followed by centrifugation of each of the treatments (MC and EI). Thus, the weights and treated data were measured based on the average of the repetitions of each treatment, while the other parameters were subjected to simple analysis of variance (ANOVA) (p<0.05). In the standard culture (MC) it was possible to observe a yield of 0.520g, while in the alternative medium (EI) the yield was 0.890 g. Furthermore, bioremoval was found in 100% nitrate, 76.3% ammonia and 7% total phosfor. It was possible to conclude that the cultivation of microalgae in industrial effluents does not negatively affect the production of Chlorella vulgaris biomass, which may be a possibility of reducing the costs of producing green energy from algae biomass, in addition to having the capacity to reduce nitrogen compounds in the effluent.