(1) Center of Excellence in Analytical Chemistry, University of Sindh, 76080 Jamshoro, Pakistan
Abstract:
The distribution and speciation of toxic metals in industrial wastewater sludge (IWS) was investigated. In this work, the
modified BCR three-stage sequential extraction procedure was applied to the fractionation of Cr Pb Ni, and Cd in untreated
industrial wastewater sludge from industrial sites in Hyderabad (Pakistan). The extracts were analyzed using electrothermal
atomic absorption spectrometry. The procedure was evaluated using a certified reference material for soil mixed with sewage
sludge BCR 483. The results from the partitioning study indicate that more easily mobilized forms (acid exchangeable) of Cd
were dominant. The oxidizable fraction was dominant for all four toxic metals. Metal recovery was good, with <4% difference
between the total metal recovered through the extractant steps and the total metal determined after microwave digestion. Lixiviation
tests (DIN 38414-S4) were used to evaluate the leaching of toxic species from IWS, and it was observed that levels of leachable
toxic metals were low compared to the amount of metal extracted in the exchangeable fraction of the BCR protocol.