Use of effluents and composted sewage sludge on the bioavailability of heavy metals in a tropical soil

Abstract

The objective of this study was to evaluate the impacts of irrigation with treated effluent of domestic origin (EET) and different doses of composted sewage sludge (CSS) on soil chemical attributes and heavy metals bioavailability after five years of application. The experimental design was completely randomized, in an arrangement of subdivided plots, with ten replications. The plots contain two types of water for irrigation (EET-treated domestic effluent and AP-potable water) and in subplots doses of organic compound (CSS-50, 100, 150, 200 and 250%), whose fertilizer quantities were based on the nitrogen fertilization required for the cultures, as reference. Results showed that levels of heavy metals As, Ba, Cd, Cr, Cu, Hg, Pb, Ni, Se and Zn did not exceed the limits and the maximum permissible content in the soil. Fertilization with composted sewage sludge associated with effluent irrigation positively impacted soil chemical quality in organic matter content, pH, bases sum (SB), base saturation (V%) and CEC. Responses obtained in this study showed a direct relationship between the type of water for irrigation and doses of compound in all evaluated parameters.