B. Karwowska
Czestochowa University of Technology, Faculty of Infrastructure and Environment, Częstochowa, PL


Heavy metals characterize possibility of mobilization and transport in environment as a result of changes in condition of ecosystem. They are significantly dangerous for natural environment. Sewage sludge accumulate different contaminations, both inorganic and organic. Among them heavy metal compounds constitute a group of chemicals, what are toxic for humans, non-biodegradable and accumulating in living organisms. Recently, there has been great interest for the removal of heavy metals from sewage sludge with different chemical compounds solution and investigations of the transformation and distributions of heavy metal in sediment. The aim of our study was to evaluate the influence of citric acid extraction on the chemical fractions and mobility of heavy metals in sewage sludge. Efficiency of citric acid extraction was determined after the samples of sewage sludge shaking with 0.1M solution of citric acid. Samples of sewage sludge before and after washing were analyzed for fractionations of zinc, copper, nickel, lead and cadmium using BCR procedure. The total content of heavy metals for both sludge was also analyzed. Citric acid solution was effective washing medium for metals extraction from municipal sewage sludge. Metals were removed from all fractions, but in different efficiency. Zinc was washed generally from II and III fraction. Copper content decreased significantly in III fraction. The highest changes in amount of nickel were in II as well as I and III fraction. Changes in lead amount were the highest in IV and II fraction. Changes in cadmium content were observed mainly in III fraction.

Acknoledgments: This work was supported by the Czestochowa University of Technology project: BS-PB-402-301/2011

Keywords: sewage sludge, heavy metals fractionation, citric acid extraction