Recycling of sewage treatment plant (STP) waste in red ceramics

This study aimed to evaluate the use of sewage treatment plant (STP) waste on the production of red ceramic. The raw materials used were clayey ceramic body and STP waste from Campos dos Goytacazes - RJ. The raw materials were characterized through techniques of X-ray fluorescence and X-ray diffraction; moreover. The thermal behavior of STP waste was evaluated by DSC/TG/DTG analysis. The formulations of the clayeys ceramics were prepared with use 0, 3, 5, 10 and 15 wt% STP waste. Through these formulations, specimens were prepared by extrusion with 30% moisture content and fired at 800 °C. The evaluated physical and mechanical properties of the fired ceramics were water absorption, linear shrinkage, flexion strength and relative density. The microstructure of fired pieces was investigated by scanning electron microscopy. The results showed the STP waste increased the resistance to flexion and water absorption. The use of the waste improved the mechanical strength of the ceramic mass and tended to increase the flexural strength with the increase in the waste content added to the specimen. This type of waste can be aproveited in red ceramic by up to 15% by mass.