Ispitivanje mogućnosti primene ubrzane karbonizacije u procesu solidifikacije/stabilizacije sedimenta zagađenog teškim metalima

Abstract

This dissertation investigates the application of accelerated carbonization as a technique for improving the solidification/stabilization treatment of sediment contaminated with heavy metals. In the first part of the research, the accelerated carbonization method is optimised for use to improve the treatment of solidification/stabilization of contaminated sediment. In the second part of the research, solidification/stabilization (S/S) and solidification/stabilization with accelerated carbonization (S/S/K) treatments are applied to contaminated sediment of the Begej canal which had previously undergone electrokinetic treatment. Wheat and soybean straw bio-ash and molasses bio-ash were used as immobilizing agents. After treatment of the monolithic mixtures, risk assessment was performed using a sequential extraction procedure and the DIN 3841-4 S4 and TCLP leaching tests. The influence of accelerated carbonization on the efficiency of S/S treatment was assessed, and the most efficient immobilizing agent was investigated, in order to provide an in depth insight into the application of the S/S and S/S/K treatments on the metals-contaminated sediments of the Veliki bački canal. In addition to bio-ash from wheat and soybean straw, calcium oxide was also used as an immobilizing agent. Leaching tests and the sequential extraction showed that accelerated carbonization has a positive effect on the immobilization of critical metals (Zn, Cu and Cd) in monolithic mixtures, which correlates with an increase in carbonate phase (confirmed by XRD and SEM/EDS analysis), as well as a lower toxicity of the monolith relative to the contaminated sediment. The results of the applied DIN 3841-4 S4 and TCLP tests show that all the monolithic mixtures are categorized by the relevant Serbian Regulations as non-hazardous and safe for disposal, based on the leached concentrations of Zn, Cu, Cd and Ni. The newly developed S/S/K method for treating polluted sediment enables the use of large amounts of bio ash (waste use) and the reduction of carbon dioxide emissions into the atmosphere by its long-term storage and sequestration in monolithic mixtures which are safe for disposal.