Lead as a heavy metal from urban wastes of Maringá PR

Abstract

Human wastes are a permanent environmental challenge. Present research analyzed the amount of lead in the sewerage and sludge of the Sewerage Treatment Stations (STSs) of Maringá PR. Samples collection were undertaken at STSs. Sewerage samples were digested with nitric acid and reduction volume. Biosolid samples previously dried at constant weight were ground and digested by aqua regia. Metal concentrations were determined by atomic absorption spectrometry. The pH, nitrogen, carbon and organic matter (OM) were determined by the respective classical methods. Total average values were: a) Pb in affluent sewerage 0.089 and effluent sewerage 0.070 µg.mL^-1. b) biosolid: Pb = 388.8 µg.g^-1; pH = 3.38; N = 3.24 %; C = 24.5 % e OM = 42.1 %. Based on variance analysis of experimental values taking into account the variation sources of the stations (STSs) and collecting time, it has been reported that, at level of 1 % confidence, there were no significantly difference between the values of lead concentration, N (%), C (%) and organic matter (%) respectively in the two variation sources. Amounts of organic matter and C:N (carbon:nitrogen) ratio of sewage sludge are appropriated for soil application