Avaliação da capacidade de espécies fúngicas para o tratamento de efluente sintético contaminado por zinco

Abstract

The accumulation of heavy metals can generate several damages to the environment. In water bodies, they can affect groundwater, contaminate animals and plants that depend directly or indirectly on these affected water bodies and, finally, compromise public health through direct or indirect consumption. The Sepetiba Bay region is an example of a water body highly contaminated by heavy metals, since its surroundings are home to many industries that release waste and effluents without treatment or with precarious treatment. The metallurgical sector is responsible for the release of 88% of these toxic metals in the region and among the most predominant is zinc. Remains of this form of pollution are difficult to treat and conventional methods are not enough for the remediation of metals to be carried out in an acceptable way, that is, within the parameters imposed by CONAMA. It is for this reason that there is a search for new treatments, so that they complement or replace the conventional ones. Given this, the present work addresses the application of bioremediation, a method of remediation using microorganisms, as a complementary or substitutive treatment. For the current research, filamentous fungi were used to remove zinc. Then, two fungal genera were evaluated for their ability to act as good zinc removal agents from synthetic effluents. The strains that make up these genera are: Penicillium purpurogenum IOC 3918, using only one strain, and Aspergillus versicolor, with two strains, IOC 4266 and IOC 4271. In previous research, the choice of fungal species and mineral medium was determinated. In the current work, tests were carried out to choose the carbon source responsible for fungal growth, among them: maltose, xylose and galactose. The dry weight of each fungi was also evaluated to obtain the “Q” value, indicating the best zinc removal agent. This value represents the mass of fungal biomass (in grams) needed to remove the metal in question (in milligrams). As a result, Penicillium purpurogenum IOC 3918 had its best performance with inactive biomass, using maltose, since it presented a Q value equivalent to 263.65 mg/g, the highest value removed in the present study. Aspergillus versicolor IOC 4266 reached the Q value corresponding to 228.11 mg/g using maltose and inactive biomass. Aspergillus versicolor IOC 4271 presented the value of 216.07 mg/g using xylose with inactive biomass. Therefore, the inactive biomass proved to be more effective and Penicillium purpurogenum IOC 3918, the strain with the greatest potential zinc remediation. In terms of percentage of removal, the three strains presented excellent averages, being above 97%, all of them using active and inactive biomass.