The representative sample of waste sludge was collected in water treatment plant in the region of Campos dos
Goytacazes-RJ, Brazil. The waste sludge was sedimented to remove the excess water, homogenized and subjected to
drying in an oven for 48 hours at 110 °C. The dry waste was sieved until a fraction passing through a 35 mesh (425
um ASTM) sieve