A multi-component numerical leach model coupled with a general chemical speciation code

A multi-component numerical leach model (SBLEM) was developed by coupling a general chemical speciation code with a modified Crank–Nicolson algorithm to determine the leaching behavior of contaminants in stabilized/solidified (s/s) wastes. The thermodynamic database of the speciation code was modified using batch leaching data. SBLEM was evaluated by simulating a dynamic leaching test of cement-treated combined bottom and fly ash from a municipal solid waste (MSW) incinerator. Simulations used an input composition prepared from acid neutralization capacity (ANC) test data of the ash. The results show that SBLEM can reasonably predict the dynamic leaching behavior of metals from the cement-treated ash when the ANC of the ash and pH-solubility curves of metals are well described. This indicates SBLEM simulations may be able to augment or replace experimental leaching tests that can consume a substantial period of time (>2 months) and in some cases, provide unreliable results.