Leaching test for assessing compliance with environmental requirements of fired clay bricks incorporated by deinking paper sludge

Abstract

The deinking paper sludge (DPS) generated by paper recycling incorporated in ceramic pastes has received significant attention to develop environmentally-friendly construction materials with a good thermal and sound insulation characteristic while maintaining a resistance mechanical acceptable by standards. The environmental risks associated with the incorporation of these sludge into clay bricks that rich in heavy metals such as Cr, Pb, Zn, Cu, Ni, etc. have been evaluated. The evaluation of these metals was carried out by performing the leaching test in order to be able to introduce this new material in the list of materials to be marketed in the field of civil engineering. Leaching tests were performed on clay, DPS and the finished product as fired bricks. Leaching results on clays show that they are non-hazardous products, while heavy metal leaching of DPS is above the limiting concentrations, which classifies DPS as a hazardous waste. In contrast, the leaching concentrations of the bricks incorporated by DPS, show that the heavy metals were immobilized in the ceramic structures of all the fired bricks. In this study, the percentages of DPS added in the composition of the bricks are 8%, 10% and 12%. Results of leaching test suggest that replacing up to 12% of clays with DPS can provide bricks to reduce the environmental impact of abundant waste and preserve non-renewable natural resources.