Fractionation of Selected Heavy Metals (Zn, Ni, Cu) in Municipal Sewage Sludges 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 Zn, Ni and Cu, organic matter and dry mass. The contents of the above-mentioned elements in fractions were evaluated using modified BCR method (four fractions: F1-acid soluble and exchangeable, F2-reducible, F3-oxidizable, F4-residual). The zinc content (mean values) in particular fractions can be arranged quantitatively in a sequence: F3 (60.8%) > F2 (20.0%) > F4 (19.9%) > F1 (3.9%), in the case of nickel: F3 ( 48.6%) > F2 (25.2%) > F4 (25.1%) > F1 (5.6%) and in the case of copper: F4 (66.3%) > F3 (35.3%) > F1 (4.2%) > F2 (3.0%). Cumulative content of zinc in mobile fractions (F1+F2+F3) ranged from 76.0 to 93.3%; for nickel from 56.3 to 89.6% and for copper from 28.8 to 53.3% of pseudo-total content.