Avaliação do desempenho da Thypha domingensis e Eichhornia crassipes como fitorremediadoras para remoção de Fe e Mn de águas destinadas ao abastecimento das Minas do Camaquã

Abstract

It is known that drinking water is an essential resource for the survival of all living beings, but nowadays it has become increasingly limited, whether due to waste, population growth or industrial expansion. In order for the water to become drinkable and accessible to the population, it is important that it be subjected to treatments carried out in a water treatment plant, meeting the potability standards required by the Ministry of Health. Every source responsible for supplying the population is characterized by several physical-chemical and bacteriological analyzes, and thus it is possible to allocate the best treatment. Among the various characteristics found in the capture for supply, are the levels of heavy metals, which in high amounts become a major problem, as the ions of Fe and Mn, for example, cause deposits and incrustations that allow the appearance of bacteria harmful ferruginous in the supply networks, and consequently the appearance of color, taste and odor, in addition to the excess of them being adverse to health. Although there are numerous technologies capable of removing heavy metals from the water, such as filtration with membranes, chemical precipitation, among others, the use of these has high costs, which often make them unfeasible. Given this fact, in this study, the phytoremediation technique was approached, which consists of using plants to remedy contaminated environments. Based on the above, the main objective of this work was, then, to evaluate two species of aquatic macrophytes in the retention of heavy metals, such as Fe and Mn, from the João Dias stream dam, source of water in the Minas do Camaquã river. The aquatic macrophytes used for the phytoremeidiation process were Thypha Domingensis - Taboa and Eichhornia Crassipes - Aguapé, both with different characteristics that demonstrate their potential in the extraction of heavy metals. The applied methodology was based on the creation of three distinct systems, and on the characterization of the before, during and after the one submitted to the phytoremediation process. System 1 was composed by the species Eichhornia crassipes - Aguapé, system 2 by the species Thypha domingensis - Taboa and system 3 by the two species. The characterization of those originated during the months of February to March 2021, lasting 34 days. As a characterization, the parameters of pH, turbidity, electrical conductivity, total dissolved solids and levels of Fe and Mn were collected. The pH remained stable throughout the analysis period, maintaining an interval of 7. Whereas parameters such as turbidity, electrical conductivity and total dissolved solids, obtained better results for system 1. For Fe and Mn contents, the system containing the species Thypha domingensisproved to be more efficient for Fe retention, resulting in a retention index of 95.6% for the first 8 days, for Mn ions, both species showed satisfactory results, obtaining a retention rate above 98% for the three systems. Regarding the development of plants, Taboa showed a better development when isolated, while the macrophyte water hyacinth showed better development in conjunction with another species, showing its adaptive power.