Viability of use of sludge from sewage treatment plant in the ceramic mass production of ceramic bricks

The sludge generated in sewage treatment plants has become a growing problem and it is considered waste. This work aims to verify the feasibility of incorporating the sludge from sewage treatment plants (STP) in the ceramic slurry for the production of bricks. In order to do so, sludge samples were collected at the ETE Verde SANEPAR (a sewage treatment plant) in the city of Ponta Grossa, PR, Brazil, and clay samples at S. Gerônimo Ceramics in Prudentópolis, PR, Brazil. The sludge at the ETE Verde undergoes a cleaning process, significantly reducing the concentration of pathogens in the waste. The process used is 'liming', which promotes stabilization, thermal and chemical disinfection through the addition and mixing of lime into the sludge in a percentage from 30% to 50% of the dry weight of the sludge. For the characterization of sludge and clay, X-ray diffraction, differential thermal and thermogravimetric analysis, X-ray fluorescence and particle size distribution were carried out. The compositions studied were made with additions from 5 to 50% per weight of the sludge in the ceramic slurry. After the mixing of the sludge with the clay, the samples were processed by uniaxial pressing and sintered at temperatures of 900 °C, 1000 °C e 1100 °C. The sintered samples were characterized by measurements of apparent density, water absorption, apparent porosity, mechanical strength, X-ray diffraction and scanning electron microscopy. The results showed that the addition of sludge up to 20% of the slurry of the clay meets all parameters recommended by current standards for production of bricks.

bricks; sludge; waste