Avaliação da produção de microalgas em tanques de betão

Abstract

The present work had the objective of evaluating the production of microalgae in concrete tanks. The experiment took place in 19 days, during which water quality analysis was carried out daily at 8 am and 3:30 p.m. The identification of the microalgae species was made through observation under the optical microscope and with the help of the phytoplankton identification guide. In order to extract and determine the concentration of chlorophyll-a, the samples were collected in the water column in each tank, after which the chlorophyll pigments were extracted, where the absorbance values of chlorophyll were obtained in the 610nm wavelet and 660nm. At the end of the experiment, the microalgae were collected with the aid of a 60μm plankton net. Subsequently, the determination of the fresh and dry biomass was carried out after the evaporation of the water. The results of the water quality showed great variations of temperature and oxygen throughout the days of cultivation, whose minimum and maximum values were 21 ° C and 28 ° C, 5.4 mg / l and 15.6 mg / l, respectively. The salinity variations were not significant, values obtained were between 12.1 ppm and 17.7 ppm, while pH values tended to remain stable, between 7.2 and 8.6. During the experiment 6 species were identified, namely Nitzschia sp, Skeletonema sp, Cyclotella sp, Chorella sp, Chaetoceros sp and Euglena sp. The concentration of chlorophyll-a at the beginning and at the end of the experiment was 11.1 μg / l and 152.7 μg / l. The average values of fresh and dry biomass obtained at the end of the experiment were 16 kg and 14 kg. These results allow to conclude that factors such as temperature and nutrients have a greater influence on the production of microalgae biomass.