Efficiency of various binders in solidification/stabilization of heavy metals and compressive strength in sludge of Ceramic tile factory Niloufar in Birjand

Heavy metals are found in high concentrations in industrial wastewater and cause damage to humans and other organisms by entering to water, soil and food chain. Stabilization and solidification is a common process in the treatment of sludge containing heavy metals. In this study, solidification/stabilization of ceramic tile industry sludge was investigated using cement and additives like water, lime, microsilica and ordinary clay.

In this study, by designing the tests by response surface methodology, the effect of different additives on compressive strength and metals concentration after pollution leakage test was investigated. So, hazardousness of wastes after stabilization and solidification and the samples tolerance against the environmental loads was evaluated.

Results showed the highest value compressive strength in high amounts of cement. Decreasing the amount of waste and replacing more lime, clay and microsilica, the compressive strength was increased. In optimal mode, by 5.77% lime, 8.69% clay, 4.35% microsilica and 51.84% cement, the maximum compressive strength was achieved about 116 kg/cm2. The minimum concentration of Cr was 0.0782 mg/L and resulted from 11.23% lime, 21.31% clay, 10.65% microsilica and 27.46% cement. Minimum Pb concentration (0.0043 mg/L) was obtained in 11.23% lime, 21.31% clay, 4.35% microsilica and 33.76% cement.

The more efficiency on compressive strength is related to cement. In addition, applying the lime, clay, microsilica and cement concluded the effective reduction of Cr and Pb concentration in leaching the stabilized samples.