DETERMINATION OF HEAVY METALS IN SEWAGE SLUDGE SYSTEMS
Keywords:
water, sewage sludge, heavy metals, sewage systemAbstract
Sewage sludge obtained in Wastewater Treatment Plants can be used as fertilizer in agricultural land. Nevertheless, it is necessary to know it load of pathogenic microorganisms, organic compounds and heavy metals. Here, we used X-Ray Fluorescence and Atomic Absorption Spectrometry to evaluate the load of Cd, Cr, Cu, Fe, Mn, Ni, Pb and Zn in sewage sludge obtained from Companhia de Saneamento Jundiaí, São Paulo
State. Due to the limited number of reference materials with similar matrices of that of interest, we developed an analytical program based on fundamentals parameters of photons absorption and excitation - relaxation of X-rays, using pressed pellets. The solutions used in Atomic Absorption Spectrometry were prepared by modifying a standard method of acid digestion for soils, developed by United States Environmental Protection Agency. The validation was done using standard certified materials. The results of Atomic Absorption Spectrometry are slightly smaller than those obtained by X-Ray Fluorescence, probably due to the incomplete acid digestion of the samples. The sewage sludge of Companhia de Saneamento Jundiaí showed smaller load of heavy metals than the maximum allowed by the regulations about application of this kind of biossolids in agricultural soils.
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