Heavy metal leaching of fly ash from waste incineration with gluconic acid and a molasses hydrolysate

The application properties of sugar acids and a hydrolysate containing sugar acids were investigated in order to evaluate their potential for removing heavy metals from waste incineration residues. Exemplarily the biomass residue molasses, which is rich in carbohydrates, was oxidized under acidic conditions to yield a hydrolysate containing natural chelating agents. The leaching capacities of the complexing agents containing solutions were examined in a series of batch tests with a fly ash from municipal waste incineration. Gluconic acid with a concentration of 0.5%, 2% and 5% and a molasses hydrolysate with a sugar acid content of approx. 1.8% were applied. It is demonstrated that sugar acids, as well as a biomass hydrolysate, which contains sugar acids, can be used as effective agents for the remediation of heavy metals which are bound to or included in the matrix of waste incineration residues. Advantageous for the leaching process is that sugar acids are particularly effective in the pH range which is normally measured for waste incineration residues.