Immobilization of chromium in cement matrices after treatment by stabilization/solidification of solid chemical residues

Resumen

Residues generated at the Universities represent 1% of the total waste in relation to other sources that generate solid waste, however, they have difficulty in treatment due to the amount and diversity of compounds present in a single waste. The residues are classified according to characteristics of flammability, corrosivity, reactivity, toxicity and pathogenicity (Class I) or biodegradability, combustibility or solubility in water (class II A or class II B). When they are classified as dangerous, they cause damage to health and the environment. An alternative treatment is stabilization/solidification, which promotes the incorporation of waste into cementitious matrices. The objective of this work was to immobilize chromium present in solid residues from chemical laboratories in cementitious matrices, aiming to reduce the environmental impact caused by the inappropriate destination of this type of residue. The specimens were made with pozzolonic Portland cement, fine sand, gravel and solid chemical laboratory residue. After integrity/durability tests and immobilization of contaminants, the best results were found for the incorporation of 5% of solid laboratory residues. Despite the 35% matrix having failed the leaching test, all treatments showed chromium retention efficiency above 93%, indicating that there was a significant reduction in the metal concentration in the residue after treatment.