Fractionation of Heavy Metals (Pb, Cr and Cd) In Municipal Sewage Sluges from Podlasie Province

In the samples of fresh dehydrated sewage sludges from municipal treatment plants in Grajewo, Bielsk Podlaski, Sokółka, Dąbrowa Białostocka, Knyszyn, Mońki, Augustów, Suwałki, Sejny and Suchowola the following determinations were made: pH, pseudo-total content of Pb, Cd and Cr, organic matter and dry mass. The contents of the above-mentioned elements in fractions were evaluated using modified BCR method (four fractions: 1-acid soluble and exchangeable, 2-reducible, 3-oxidizable, 4-residual). The lead content (mean values) in particular fractions can be arranged quantitatively in a sequence: F4 (51.4%) > F2 (30.3%) > F3 (19.2%) > F1 (7.2%), in the case of cadmium: F4 (49.0%) > F2 (23.6%) > F3 (18.9%) > F1 (15.5%) and in the case of chromium: F4 (65.0%) > F3 (30.6%) > F2 (6.8%) > F1 (3.1%). Cumulative content of lead in mobile fractions (F1+F2+F3) ranged from 20.7% to 89.9%; for cadmium from 32.9% to 76.9% and for chromium from 27.5 to 58.6% of pseudo-total content.