Abstract
For the purpose of the early stabilization of MSW bottom ash, we investigated Pb insolubilization treatments that can be combined with water sprinkling treatments to wash out salts. For the insolubilization treatment method, we conducted column tests to verify sprinkling treatments with chemical agents in solution and accelerated carbonation treatments using CO2 gas. We used sodium bicarbonate (SHC), phosphoric acid (PA) and organic chelate (OC) as the chemical agents.
For the chemical sprinkling treatment, we confirmed Pb insolubilizing effects for all the chemicals. In the OC group, the Pb concentration was 0.01 mg L－1 in all layers, but in the SHC and PA groups, the reaction also progressed with Ca in the bottom ash, and the effect was reduced in the lower layers of the columns.
In the accelerated carbonation treatment, we estimated that the threshold value of the CO2 supply amount at which the Pb insolubilizing effect is observed was about 30-40 g kgDW－1. We confirmed that the same effect can be obtained even with the CO2 concentration changed from 100 % to 10 %. In addition, we verified the effectiveness of the order of the combination of water sprinkling and carbonation.
