[Effects of adsorbents on partitioning and fixation of heavy metals in the incineration process of sewage sludge].

ABSTRACT

Experiments were carried out on laboratory-scale electrically heated tube furnace sewage sludge combustion with different adsorbents. Four solid adsorbents (calcium oxide, Alumina, fly ash and kaolin) were used to control the emission of heavy metals (Pb, Cd, Cu, Cr, Ni, Zn) during the sewage sludge incineration. The results showed that the heavy metals tended to be fixed and left over in the incineration bottom ash with the addition of calcium oxide, Alumina, fly ash and kaolin. With the increase of the solid adsorbent ratio, the residual rate of heavy metals in the bottom ash also increased. Incineration temperature had a great influence on the heavy metal adsorption effect of the solid adsorbent. The forms, melting point and boiling point of the heavy metals were found to be important factors that determined its volatility. There was huge difference in the inhibitory effect of different adsorbents on heavy metals migration. From the view of controlling heavy metal evaporation, the adsorbents kaolin and CaO were superior to the other adsorbents. The interaction between the active center of the solid adsorbent and the molecules of the heavy metal compounds depended on the distribution of these active sites and the chemical properties of the heavy metals.