Preliminary study of the levels of metals potentially toxic in soil after sludge disposal in natura of the station of water treatment

Abstract

Due to the fact the sludge has intense influence anthropic, its use must be the source of study because it has significant quantities of metals potentially toxic and if it is handled incorrectly, it can contaminate the soil and the water at the disposal place. This way, the goal of this study was to evaluate the effect of the application of the sludge of the water treatment station on the chemical characteristics and on levels of metals potentially toxic from a medium textured soil. The experimental design used was completely randomized with four treatments and four repetitions, totaling 16 experimental units. The experimental units consisted of 1 polyethylene pot filled with 6 kg of substrate (soil or soil + sludge). The first treatment was filled to soil, functioning as a control. Other treatments consisted of sludge doses that corresponded to 75, 150 and 250 kg ha-1 sludge by soil. The study was conducted at the chemical laboratory of CESI-UEMA. The addition of sludge promoted significant changes in chemical properties of the soil, for example CTC, organic matter and pH. These changes contributed to increase soil quality. Under the conditions studied, the levels of copper, lead and chromium are within the tolerable limits of these metals in soils according to criteria established by CETESB and CONAMA.