presents the chemical composition of the waterworks waste sample. Although the properties of the sludge samples are highly variable and dependent on both the type of the raw water and the chemical composition of coagulant [21], it can be seen from Table 2 that aluminum is the dominant component in the dewatered alum sludge with ~39 % in mass expressed as Al2O3. The other principal chemical components were SiO2 and Fe2O3.