Estudo da viabilidade da remoção de metais potencialmente tóxicos de um igarapé da região do Polo Industrial de Manaus (PIM) utilizando um sistema piloto de tanque com macrófita e wetland construído

Abstract

Constructed wetlands are projected systems aim to removing organic pollutants (aromatics, organ chlorine, etc) and inorganic (nitrogen, phosphorus, heavy metals) of contaminated water. This system presents several applications for cleaning domestic effluent and industrial wastewaters. Thus, a pilot system comprised of a tank with Pistia stratiotes (a floating macrophyte species) coupled to a filter planted with Alocasia machorriza cultivate in clayey soil, chemically modified was made in this work in aim to remove TPM (Fe, Mn, Cu, Co, Ni, and Cd) of contaminated water from Igarapé do Quarenta stream (Manaus Industrial Pole). Initially, the ability of the macrophyte Lemna aequinoctialis to remove heavy metal was studied in two different sampling times during its flowering. Concentrations of Ni, Cu, Co, Cr, Mn, Pb, Zn, and Fe present in Lemna aequinoctialis and water were determined by flame atomic absorption spectrometry (FAAS). We found that rhizofiltration of Lemna aequinoctialis removes high amount of heavy metal in this order: Cr >Ni>Cu> Fe > Zn >Mn. Only significant changes in chemical composition of the water, pH and electrical conductivity alter the absorption capacity of Lemna aequinoctialis. The physical and chemical properties of the water became impracticable the using of the Lemna aequinoctialis in purification water pilot system. Unlike its natural conditions the Lemna aequinoctialis showed no income and no survival needed to be used in a water purification system. In a second step after testing, a pilot system comprised of a tank with Pistia stratiotes (a floating macrophyte species) coupled to a filter planted with Alocasia machorriza cultivate in clayey soil, chemically modified showed better findings. The system received three shipments of contaminated water from the Igarapé do Quarenta stream in the range of 24 hours to complete 120 hours. Every 24 hours, samples of water from the pilot system were collected and the following variables determined pH, conductivity and concentration of MPT. Findings showed that the pilot system reduces the concentration of studied MPT being most effective for Co and Pb. The Pistia stratiotes remove more MPT than the filter planted. The Pistia stratiotes absorbed high concentrations of Pb and Fe in their roots and leaves, Alocasia machorriza Ni and Pb in their leaves, Co Ni in their stems and Pb, Ni and Co in their roots.