Detoxification of a highly toxic lead-loaded industrial solid waste by stabilization using apatites

Apatites are known for their properties to immobilize lead contained in aqueous solutions or contaminated soils. In this study, apatites were examined as stabilization additives for lead-loaded industrial solid toxic wastes. The specific waste was the residue, obtained after thermal treatment of sludges (incineration), which was derived from tetraethyl lead fuel storage tanks. It was found to contain around 30 wt.% lead and 33 wt.% iron. Standard leaching tests (according to DIN 38414 S-4) were applied for the determination of leachability of metals from the ash and, thus, of chemical toxicity; the proposed leaching tests examined both initial and stabilized products in order to evaluate the effectiveness of the applied additives. The results obtained demonstrate the fact that lead concentrations in leachates, after the application of the proposed leaching tests using apatites as additives and with a ratio of 50% solid waste-50 wt.% apatite, could be reduced to the range of 1mg/l.