Combined effects of FeCl3 and CaO conditioning on SO2, HCl and heavy metals emissions during the DDSS incineration

Batch incineration tests of sludge before and after conditioning were conducted in atmospheric conditions to investigate the emissions of SO2, HCl and heavy metals using a simulated laboratory tubular-furnace reactor. The results show that when the temperature increased from 600 °C to 900 °C, the emissions of SO2 and HCl increased before sludge conditioning. After conditioning with FeCl3/CaO, the SO2 emissions was reduced and the conversion of Cl to HCl decreased, but HCl emissions increased. When the temperature was above 900 °C, the conditioner had a weak effect on fixing the S and Cl emission. After conditioning with FeCl3/CaO, Pb, Zn, and Cu concentrations in the bottom ash decreased, the volatility of Cu and Cr improved. Chlorine exhibited larger effects on the volatilization of heavy metals than did CaO. The consistency between the above experimental results and the model predictions based on a thermodynamic equilibrium analysis was confirmed.