Effect of heating temperature on the sintering characteristics of sewage sludge ash

This study investigated and analyzed the effects of the heating temperature on the properties of the sintered sewage sludge ash. The results indicated that the water absorption rate of the sintered sewage sludge ash samples decreased when the firing temperature was increased from 800 to 900 °C. When the heating temperature reached 1000 °C, the absorption rate decreased significantly. The bulk density of the sewage sludge ash samples increased by 2.3 g/cm3 when the heating temperature was increased from 900 to 1000 °C, indicating that the densification was affected by heating. The porosity of the sintered sewage sludge ash samples ranged from 36% to 39% when the heating temperature ranged from 600 to 900 °C. The least porosity occurred at 1000 °C; the sintered samples were well densified. When the temperature was between 900 and 1000 °C, the strength appeared to increase significantly, reaching 2040 kgf/cm2, implying an advance in densification due to sintering. The SEM observations were in general agreement with the trends shown by the density data.