Wpływ sposobu stabilizacji chemicznej na zmiany form Zn i Cu w osadach przefermentowanych

The aim of the study was to evaluate the bioavailability of Zn and Cu in digested sewage sludge chemically stabilised with CaO, Fenton’s reagent or peracetic acid. Sewage sludge samples were taken from closed fermentation chamber of municipal wastewater treatment plant. Calcium oxide (CaO), Fenton’s reagent or peracetic acid were added into the sludge. Total reaction time was equal to 24 h. After stabilisation, total Zn and Cu content in the sludge was analysed. Speciation of chemical forms of heavy metals was also done. Speciation of heavy metals was done by modified Tessier method. Five fractions were separated. Total concentration of Zn in sewage sludge was equal to 863.5 mg Zn/kg s.m. Zn in control sludge was mainly present in fraction II (74%). Total concentration of Cu in sewage sludge was equal to 190.8 mg/kg s.m. Cu in control sludge was mainly present in fractions IV (42.5%) and II (37%). Chemical stabilisation with CaO did not cause important changes in Zn and Cu content in individual fractions. Stabilisation with Fenton’s reagent and peracetic acid decreased these metals content in fraction II (bonded with carbonates). The use of advanced oxidation processes did not release Zn and Cu from fractions IV and V.