Solidification/stabilization of hazardous waste sludge obtained from a chemical industry

In this study, treatment sludge obtained from a chemical-metal finishing industry, which contained potentially toxic heavy metals and organics, was characterized, and the performance of the solidification/stabilization (S/S) of the sludge was discussed. The hazard characteristics of the waste were determined by means of extraction procedure toxicity test and DIN 38414-S4 Test, as defined in both Turkish and USEPA regulations. S/S studies were conducted using Portland cement to solidify the sludge containing high concentrations of total organic carbon, Cr, Cu, Hg, Ni, Pb, and Zn. The waste/binder ratios of 36 sludge specimens were kept between 0/100 and 40/100. The specimens were cured at room temperature for 7, 28, and 90 days. The compressive strengths of the specimens were measured to determine the feasibility of using solidified waste sludge as construction materials. The compressive strength values indicated that specimens could be potentially used as construction materials. The heavy metal and organic contents of the extracts of each specimen were detected in concentrations which were lower than the standard concentrations in EPTox and DIN 38414-S4 leaching procedures for the most part.