CHALLENGES OF THE REPUBLIC OF SERBIA IN THE TREATMENT OF WASTE SLUDGE CONTAMINATED WITH HEAVY METALS

The interactions of heavy metals and cement phases in the solidification/stabilization (S/S) pro-cess have been examined. The S/S method was applied to the waste sludge contaminated with heavy metals to determine the conditions under which the treated materials can be safely disposed of at land-fills for inert, non-hazardous, or hazardous waste. Sludge samples were mixed with soil and sand to simulate improper sludge disposal directly into the soil. S/S technology was selected using different cement fractions to treat these contaminated samples. The use of Portland cement or mixtures of dif-ferent types of cement for the treatment of sludge containing heavy metals is widespread. Samples of leached content were analyzed for the presence of the following metals: arsenic (As), cadmium (Cd), chromium (Cr), copper (Cu), nickel (Ni), and zinc (Zn). The study results lead to the conclusion that the sludge contaminated with heavy metals after the application of S/S with the addition of different cement fractions is transformed into non-hazardous, monolithic material.