Copper and zinc fractionation in biosolid cultivated with Pennisetum purpureum in different periods

ABSTRACT In order to reduce the effect of heavy metals on the biosolid, it is necessary to promote its phytoremediation. It is important to know the total content and chemical forms of these elements in the residue for analyzing its behavior and potential toxicity. Thus, the aim of this study was to evaluate the fractionation and behavior of Cu and Zn in biosolid cultivated with Pennisetum purpureum in different periods. The experiment was carried out using a randomized complete block design. The treatments, with five replicates, corresponded to Pennisetum purpureum cultivation in biosolid for 30, 60, 90, 120 and 150 days after planting. The total contents of Cu and Zn in the biosolid remained below the critical limits established by the CONAMA Resolution 357, and there was a reduction in these values with Pennisetum purpureum cultivation. Furthermore, the increment in the grass cultivation period caused intense reduction of Zn contents bound to organic matter, but there was an increase in soluble Zn and residual Zn. Additionally, there was an intense reduction in the content of Cu bound to sulfides. Therefore, for biosolid phytoremediation purposes, the grass should be cultivated for 150 days.