Transformation of hazardous residues from medical laboratory waste treatment plant into permeable brick

Abstract In this study, the transformation of hazardous residues (fly ash, silica gel, bottom ash, and sludge) from a medical laboratory waste incineration system of Sustainable Environment Research Center into permeable bricks was investigated. The fly ash was elutriated using water twice to remove the Cl−. The elutriated fly ash was mixed with silica gel, bottom ash, and sludge with different formulas which were designed using response surface methodology (RSM) in Design Expert 8.0.6 software. The mixed materials were melted at 1450 ℃. The RSM analysis results showed that the most optimal effect was achieved when silica gel constituted 60% of the total sample and the elutriated fly ash constituted 10% of the encapsulated phase (elutriated fly ash, bottom ash, and sludge), in terms of minimizing the amount of unmelted materials and maximizing the percentage of mass reduction. The slag with optimal melting effect was mixed with cullet, clay, cement, and water, molded, cured, and transformed into permeable bricks. The physical properties met the regulations for grade-A bricks, and the Toxicity Characteristic Leaching Procedure (TCLP) results showed that metals were well encapsulated in the permeable bricks. Overall, the permeable bricks will offer sufficient physical strength and will not contribute to environmental pollution when recycled.