B. Karwowska, Li. Dąbrowska
Czestochowa University of Technology, Faculty of Infrastructure and Environment, Department of Chemistry, Water and Wastewater Technology, Częstochowa, PL

BIOAVAILABILITY OF HEAVY METALS IN THE MUNICIPAL SEWAGE SLUDGE


The purpose of presented studies was compare the amount of metals potentially available for plants with their content in chemicals forms detected with sequential extraction procedure and evaluation the hypothesis that content of metals in some fractions could be equivalent to their bioavailability The report presents results of BCR sequential extraction procedure of metals (Zn, Cu, Ni, Cd, Pb) from sewage sludge from two WWTP and single extraction with 1M HCl used for determination of bioavailable forms of metals. Our studies stated the presence of copper and cadmium generally in the organic fraction, nickel and lead in the residual fraction and zinc both in the organic as well as in the iron and manganese oxyhydroxides fraction. However determined bioavailability significantly differed from the metals content in the fractions regarded as mobile. Content of zinc in the I and II fraction was on the level 48-51% of the total amount and bioavailability 86-92%. Concentration of copper and nickel in the mobile fractions (I and II) was 2-4% and 22-33%, respectively and in bioavailable form 49-63% and 25-41%, respectively. Lead available content in sludge was in the same scheme like copper and nickel (21-22 and 51-62%, respectively). Bioavailable content detected for analysed metals covered I and II mobile fractions but for Zn, Cu and Ni also significant part of III – potentially immobile fraction. Additionally for Pb even a part of IV – assumed as practically immobile and inactive fraction. Obtained data indicated that speciation forms of metal are not always equivalent to their bioavailability.

Keywords: heavy metals, municipal sewage sludge, sequential procedure BCR, bioavailability