Incorporation of sewage sludge into heavy clay ceramic body

Abstract

This work has as its objective to evaluate the use of sewage sludge from wastewater treatment plant into heavy clay ceramic body. Compositions were prepared with amounts of 0, 2.5, 10 and 15 wt.% of sludge incorporated into the clay body. Rectangular specimens were obtained by 20 MPa pressure molding and then fired at 850oC in a laboratory furnace. Characterization of the waste was done by X-rayfluorescence, differential scanning calorimetry and thermogravimetric analysis. Ceramic properties related to the water absorption and compression strength were determined. The results indicated that the incorporation of the sludge into clay bricks must be done in low amounts. In higher amounts the sludge increases the water absorption and reduces the mechanical strength of the ceramic. This is a consequence of the changes caused in the porosity by the relatively elevated weight loss of the waste during the firing stage.