Potencial biotecnologico da microalga Synechococcus nidulans para tratamento de águas ácidas de drenagem da região de mineração em Candiota - RS

Abstract

Brazil has one of the largest coal reserves of America, the most important is the field of Candiota, located on the southern edge of the Paraná Basin, located in Candiota RS, because it has about 12 billion tons, contributes 37 9% of total national reserves. However, mining activities may cause environmental impact, regarding the drainage of water, which may contain heavy metals, resulting in inevitable damage to the environment harming water quality and the development of local fauna and flora, as well as the cultures agropastoral. Biological processes have appropriate characteristics to aid in waste water treatment. Bioremediation, attraction and retention of a substance by a body from any source is an alternative. In this context, this work aimed at the cultivation of microalgae Synechococcus nidulans in drainage waters of Candiota county mining region in order to demonstrate their biotechnological potential for the treatment of this type of effluent. Preliminary experiments were carried out with the microalgae Synechococcus nidulans to assess its favorable metabolic bioremediation of acid drainage waters, evaluating their growth at different pH values and different concentrations of cadmium. Drain water sample was taken in an area of Riograndense Mining Company, called "mesh I" that has problems with Acid Drainage Mining. He underwent drainage water microalgae Synechococcus nidulans under laboratory conditions to verify their growth and consequently its potential in the treatment of effluent from the mining activity. The experiments were performed using three different means, using only autoclaved as effluent medium, autoclaved effluent with addition of Sodium Nitrate and Sodium Bicarbonate as a means and only half Zarrouk (control) in greenhouses BOD not sterile at 28 ± 1 ° C with photo-period of 12 hours for 20 days. It was found growth and alkalinization of the medium for the experiments with different pH values when started at 6.0 to 4.0 there was no significant growth, as the pH 1.5 to microalgae did not survive. In the experiment with different concentrations of cadmium was observed that the biomass values obtained at the end of cultivation for both cultures performed only by means Zarrouk, as for the cadmium were conducted with similar. It can be inferred that somehow the microalgae assimilated the heavy metal present in the culture medium. When grown in the effluent from the final lattice I cell concentration obtained for the effluent using cultures supplemented with NaHCO3, NaNO3 obtained a higher value compared with the crops using only the effluent. This was due to the low pH that this type of effluent has, which is out of the microalgae metabolism range. Through experiments carried out with the acid mine drainage effluents generated by mining can be concluded that the limited growth of microalgae present in acid drainage waters even NaHCO3 and supplemented with NaNO3. The use of this effluent to the growth of micro-algae requires a new approach to possibly becomes a biotechnological alternative for the treatment thereof. Obtaining information to assess and demonstrate through analysis of atomic absorption retention capacity of heavy metals by microalgae, also characterize the effluent for the presence of heavy metals is required.