Caracterização da incorporação de lodo de estação de tratamento de água em matriz cerâmica refratária: análise do comportamento refratário

Abstract

Water Treatment Plants (WTP) behave as industries, changing raw water into drinking water and producing significant quantities of residues and effluents as a result. The sludge from the cleaning of inclined plates and filters is classified as solid residue and it cannot be discarded in bodies of water. Furthermore, CONAMA’s resolution n° 430/2011 classifies this material as a pollutant, due to its chemical composition, which has direct relation with the coagulant used in the treatment, basically aluminum and iron compounds. However, this material has clay minerals and silts in its constitution that is approximated to clays, optimizing its incorporation to red ceramics products. Studies conclude the incorporation of up to 15%, in weight, of the sludge to the burnt red ceramics mass between 850ºC and 1050ºC did not provoke significant alterations in the mixtures, which still comply with the standard requirements. Other studies concluded additions up to 10% of sludge have few effects on the linear shrinkage for burning temperature up to 1000ºC, but there is an increase of water absorption with decrease of mechanical resistance. Due to these studies, adding the residues incorporation techniques, the objective is to value WTP sludge through its incorporation to the manufacture of refractory ceramics pieces. The raw materials have been collected in the state of Paraná, physically and chemically featured, mixed in different proportions and burned, looking for the formulation that presents the best relation between linear shrinkage, water absorption, mechanical resistance and thermal shock resistance and provides the appreciation of this residue in coating articles. The sludge incorporation into the ceramics matrix caused increasing of loss in the fire and of the absorption with decreasing of mechanical resistance. Regarding to the thermal properties there was not sludge negative influence in the mixture. Thereby, it was concluded that it is possible to incorporate up to 10% of sludge in the ceramics matrix without great mechanical damage.