Uso de materiais inertizantes e crescimento de espécies arbóreas em solo contaminado por metais pesados oriundos da Baía de Sepetiba Itaguaí - RJ

Abstract

The development of technologies and the growth of the world population resulted in increasing the demand of consumer goods. The manufacturing process generates considerable amount of waste that if improperly treated, will serve as potential sources of water, air and soil pollution. According to the issue presented, this study aimed to achieve viable and efficient solutions in remediation of areas contaminated by heavy metals near the Sepetiba Bay, located in Itaguaí municipality, Rio de Janeiro State (Brazil). The study was divided into three stages according to the strategy used for remediation. The first step was an experiment of chemical containment, which evaluated the efficiency of industrial wastes, alkaline (steelmaking slag) and adsorbent (mill scale), reduc ing the solubility of the metals Mn and Zn in three contaminated substrates (G1, G2 and G3) from Itaguaí Port - RJ. The second stage was related to the study of tree species growth: African Cordia (Cordia africana), knew (Mimosa caesalpiniaefolia), Acacia (Acacia angustissima), and white angico (Anadenanthera colubrina), developed for approximately nine years, in an area where it was deposited a contaminated substrate, from dredging the bottom of Sepetiba Bay, and possible usage of these species in phytoremediation strategies. These first two chapters were the basis for selecting inertizant treatments and more efficient plant species for us ing in strategies for phytostabilization, studied in the third chapter. Thus, the third step was to study the development and potential of the species Cordia africana, and Acacia angustissima, grown on the substrate G1 (the most acid one as evaluated in the first stage) treated with doses of industrial waste inertizants, also determined in the first stage of study. Thus, there were used data from the first two steps for the implementation of the third, in a greenhouse experiment. In this experiment, there was an increase in contamination of the natural substrate by the addition of industrial waste (IW) originated from Cia Mercantil and Industrial Ingá plants named Ingá Waste (Class I residue), collected from improperly disposed batteries, placed on the shores of the Sepetiba Bay, and sources of environmental contamination. In the phase regarding chemical restraining, it was observed that the inertizant more efficient in reducing the solubility of heavy metals were the steelmaking slag and the mill scale. In conclusion of the preliminary study and in accordance with the adopted criteria, the Cordia africana, and Acacia angustissima were selected as possible species to be studied in phytostabilization strategies. In the third stage, it was observed that the plants of the species Acacia angustissima entered into senescence, and the Cordia africana species had higher tolerance to the treatments studied and the highest potential for programs of phytostabilization. The residues steelmaking slag and the mill scale were effective in reducing the solubility of heavy metals, allowing the development of the Cordia Africana trees.