Use of Clay Sludge Water Treatment Plant Sludge to Produce Ceramic Brick

In the search for solutions capable of minimizing the environmental impacts from waste water treatment plant (WWTP) and reduce costs related to the final destination of the waste generated, the present work aims to evaluate the potential use of WWTP sludge by incorporating clay slurry to the production of bricks, in order to present an alternative environmentally correct destination for this waste. Sludge and clay underwent chemical and mineralogical characterization, through granulometric distribution, X-ray fluorescence analysis, X-ray diffraction. The samples were homogenized in the proportions of 0%, 12%, 14% and 18% of sludge in red clay, pressed at 25 MPa, and later production of test specimens which were then burned to a temperature of 900ºC. After sintering, physical and mechanical tests were performed to evaluate the quality of the final product, by means of analysis of the properties of fire loss, linear retraction, water absorption, apparent specific mass, apparent porosity, flexural rupture stress, moisture and plasticity. The results of the laboratory tests with the residue proportions incorporated in the clay mass demonstrate influence on the physical and mechanical properties of the ceramic material. The results presented show a similarity to that recommended and that despite the 18% (sludge) samples, in relation to the clay showed a variation in the chemical composition due to its high organic matter content, it was observed that both had SiO2, Al2O3 and Fe2O3. Comparing the results with the parameters established in NBR 15270-1, 2 and 3/2005, it was verified that the WWTP sludge can be incorporated in up to 18% in the clay mass for the manufacture of bricks.