Abstract
The increased production of iron ore in recent decades to support the growing demand for steel for various industrial applications has been a challenging matter concerning environmental issues. However, since iron is an economically important metal there is a growing industrial interest to reduce the impact of its exploration in the environment. This concern did not avoid the biggest environmental disaster of Brazil’s history in 2015 when disruption of a mining dam in the city of Mariana (Minas Gerais State) released sediments of iron ore extraction to an affluent of an important watershed. Situations like this have awaked the demand for the development of new alternatives to minimize environmental problems and to remove contaminants present in aqueous matrices. Bioremediation is an innovative green process to treat water contaminated with organic and inorganic pollutants. It is a fast, efficient, and relatively inexpensive alternative when traditional chemical treatment is not the first choice, due to the interference of the latter with aquatic life. Bioremediation techniques are based on the use of fungi or bacteria (alive or deactivated), as well as agricultural by-products, as organic filters, which act by capturing metallic ions and other pollutants through adsorption or another mechanisms of chemical interaction. These filters can be easily obtained from renewable resources making the process economically viable. In this work, two species of filamentous fungi, Penicillium janthinellum and Syncephalastrum racemosum, were investigated for their capacity to remove iron present in aqueous matrices aiming at the development of a tailor-made filter for iron bioremediation. The fungi were grown for 10 and 12 days for biomass formation, respectively. The respective biomasses were recovered by filtration and subjected to aqueous solutions containing iron ions. The process was followed taking five aliquots in the first hour and then each 24 h for four days. Optimization was evaluated by varying the water content of bioremediation agents utilized (fresh or processed dry biomass) and also by exchanging the biomass for a fresh one after periods of 24, 48, and 72 h. Iron present in the aqueous matrices before and after bioremediation was quantified by atomic absorption. Results were very encouraging, with the dry biomass of P. janthinellum removing approximately 50 % of iron present in the aqueous matrices after only 1 h of contact time. After 72 h of the process, both microorganisms achieved more than 90 % of iron ions removal regardless of the type of biomass utilized in the process. The results proved that this approach is a simple and fast alternative for decontamination of water matrices contaminated with iron, with the positive aspect of the easiness of fungal cultivation, and the high yields of biomass produced. In addition, since this process does not alter the physicochemical properties of the treatment site, it stands out as a sustainable green technique to deal with processing of dynamic environments.
