Physico-chemical characterization of centrifuged sludge from the Tamanduá water treatment plant (Foz do Iguaçu, PR)

ABSTRACT The water treatment process generates a residue called water treatment plant (WTP) sludge, which needs to be correctly characterized to ensure appropriate disposal or reuse. This study aimed to characterize the centrifuged sludge produced at the Tamanduá WTP, Iguaçu Falls City, Brazil, and considered opportunities for its reuse in the production of concrete for the civil construction industry. Wet sludge (sludge in its natural form) analysis included the determination of total solids, moisture content, density, pH, and inorganic parameters (As, Al, Ba, Cd, Pb, Cr, F, Hg, Ag, and Se) through thermogravimetric analysis, X-ray diffraction, and chemical analysis by X-ray fluorescence and loss ignition. For calcined WTP sludge, chemical and mineralogical composition and laser granulometry were evaluated. The results indicated that calcined sludge had the potential to be used in the production of cement materials; conversely wet sludge did not reach the appropriate safety standards due to the high quantity of organic matter.