Keywords: heavy metals, oxidation, phosphorus, reduction, sewage sludge, TG-DTA curves, combustion atmosphere, vapourisation, environmental pollution, bottom ash, hydrogen chloride, calcium oxide
The behaviour of phosphorus and heavy metals in sewage sludge ashes
The effect of the combustion atmosphere and the additives (CaO and HCl) on the behaviour of phosphorus and heavy metals during sewage sludge combustion was investigated. The results demonstrated that the reduction combustion promoted the vapourisation of phosphorus and heavy metals during sewage sludge combustion. Moreover, the concentrations of phosphorus and heavy metals in the bottom ash decreased with increasing HCl ratio, and the addition of CaO can stabilise heavy metals and phosphorus. It was also observed that phosphorus and heavy metals increased with increasing CaO ratio. Lastly, the difference of the TG-DTA curves with and without additives is discussed.