Anais do Congresso Paranaense de Microbiologia
Anais do III Congresso Paranaense de Microbiologia

The integration of bioenergy production and wastewater treatment is a good approach to lower costs. Vinasse is an effluent resulting from the processing of sugarcane with high nutrient content and can be used for the microalgae biomass production of heterotrophic oleaginous in substitution of the culture media. Thus, the objective of the study was to determine the nutrient removal efficiency from culture medium, containing hydroponic nutrient salts supplemented with vinasse and yeast extract (MHVY), after the cultivation of freshwater Chlorella vulgaris for the production of biomass. The culture medium consisted of hydroponic salts with 40% vinasse without previous treatment, 30 mg L -1 of dry yeast extract (Saccharomyces cerevisiae) and pH adjusted to 7.0. The experiment was carried out, for 20 days, in a growth chamber under controlled conditions with a 12:12 h (light:dark) photoperiod with a photosynthetically active radiation intensity of 100 ± 20 µmol photons m -2 s -1 and temperature at 28 ± 1ºC, using flask of 250 mL and five replicates. The MHVY was inoculated with 30% (v/v) of a culture of a green C. vulgaris with concentration of 1.01 10 7 cells mL -1 , optical density at 670nm of 0.93, dry biomass of 0.39 g L -1 and pH 6.74. After 20 days of C. vulgaris cultivation, the optical density and the dry biomass increased linearly and the pH tended to be alkaline. Chemical characterization of the medium (MHVY) showed the following initial concentrations of nutrients in mg L -1 : 125.76 of nitrogen (N), 40.32 of phosphorus (P), 2033.74 of potassium (K), 148.66 of calcium (Ca), 51.30 of magnesium (Mg), 22.02 iron (Fe), 2.24 manganese (Mn), 0.020 copper (Cu) and 1.049 of Zinc (Zn). After the C. vulgaris cultivation, it was observed high reduction in the nutrient concentrations. The nutrient removal efficiency from the MHVY was the following: 76% of N, 69% of P, 8.7% of K, 51% of Ca, 26% of Mg, 67% of Fe, 82% of Mn, 100% of Cu and 44% of Zn. There was on average dry biomass production of 2.09 g L -1 with yield of 0.104 g L -1 d -1 . After cells harvest by centrifugation, the chemical oxygen demand in the MHVY was 72% lower than in the medium with hydroponic salts supplemented with vinasse and yeast extract. The results indicated that cultivation of C. vulgaris could be an alternative to remove efficiently nutrients contained in the effluent, vinasse, from the sugarcane industry and simultaneously for bioenergy and biofertilizers production.