Comparative Study of Heavy Metal Leaching from Clay – Tannery Sludge – Glass Powder Bricks using TCLP and Netherlands Tank Leaching Methods

Abstract

The work compared the leaching of heavy metals (Cr, Ni, Zn, and Pb) from the hybrid bricks using the Toxicity Characteristics Leaching Procedure (TCLP) and Netherland’s tank leaching tests. Hybrid bricks were prepared by partially replacing clay with an increasing weight percentage of tannery sludge (0, 9, 18, and 27% by weight of brick specimen) and a constant weight percentage (10% by weight of brick) of glass powder. The prepared mixes were fired to 900oC, 950oC, and 1000oC to assess the leaching potential of metals from hybrid bricks at different temperatures. The TCLP test was conducted as per the United States Environmental Protection Agency (USEPA) 1311, whereas the Netherlands tank leaching test was performed as per the NEN 7345 standard. In both methods, the leaching of metals increased with the tannery sludge amounts and decreased with an increase in temperature. The release of metals from the TCLP test was slightly higher than that of the Netherlands tank leaching test. The higher amounts of metal released from the TCLP test were due to exposure to more areas of particles due to the crushing of particles. The results obtained from the TCLP test are more appropriate to the actual field conditions arising in the service life of materials.