Pozzolanic-based materials for stabilization/solidification of contaminated sludge with hazardous heavy metal: case study

In this study, the efficiency of metals immobilization in sludge using pozzolanic materials fly ash and cement clinker dust (CCD) was investigated. Also, estimation of the optimum binder to waste ratio was determined. Different leaching tests such as the standard European (EN) 12457-2 leaching tests; the toxicity characteristic leaching procedure; and the multiple extraction procedure test were used to evaluate the efficiency of metals stabilization in sludge matrix, and they showed that the availability of metals leaching (Cd, Cu, Cr, Pb, Ni, Zn) from the stabilized sludge were lower than the permissible limit set by National and International regulations for hazardous waste management. Examination of the solidified sample for its compressive strength after curing for 28 days yielded a value of 1.55 and 4.57 MPa for fly ash, and CCD which indicates that the treated sludge was well solidified and safe to be used in a wide variety of applications, for instance as a raw material for pavement blocks.