Study of heavy metal fractionation in the Lami municipal disposal facility, Fiji

This work reports the first screening study of the bioavailability of heavy metals such as copper, zinc, lead and nickel in the Lami municipal disposal facility, Suva, Fiji where virtually uncontrolled dumping had been carried out for over fifty years. The soil samples from three parts of the facility were collected and the potential for mobility into the surrounding marine environment was assessed according to international guidelines. The results showed high levels of Pb in Site A (109.0 mg kg–1) and that Zn was the predominant metal across Sites B and C with 550.7 mg kg–1 and 206.8 mg kg–1, respectively. Ni was present in the least amount with the highest value 8.7 mg kg–1. In addition, Cu, Pb and Zn concentrations exceeded commonly used eco-toxicity threshold values. Moreover, there were indications that considerable leaching of the studied heavy metals may have been occurring for long periods of time at the sites. Overall, this study showed that even in areas with little industrialization, lack of adequate waste management controls could result in unusually high levels of heavy metals contamination of the soil. The results raise concerns about the wellbeing of the communities living adjacent to the Lami municipal disposal facility that depend on the adjacent marine environment for their subsistence.

Reed bed systems for sludge treatment: case studies in Italy

In recent years, reed bed systems (RBSs) have been widely considered as a valid technology for sludge treatment. In this study are presented results about sludge stabilization occurring within beds in four RBSs, situated in Tuscany (Italy). The results showed that stabilization of the sludge over time occurred in all RBSs, as shown by the low content of water-soluble carbon and dehydrogenase activity, which measures indirectly the overall microbial metabolism, and by the re-synthesis of humic-like matter highlighted by the pyrolytic indices of mineralization and humification. Results about heavy metal fractionation, an appropriate technique to estimate the heavy metal bioavailability and sludge biotoxicity, showed that the process of sludge stabilization occurring in RBSs retains metals in fractions related to the stabilized organic matter, making metals less bioavailable. Moreover, the concentrations of various toxic organic compounds were below the limit of concentration suggested by the European Union's Working Document on Sludge, for land application. The effectiveness of the stabilization processes in RBs was hence clearly proven by the results that measured mineralization and humification processes, and by the low levels of bioavailable heavy metals and toxic organic compounds in stabilized sludges.