Leather buffing dust in brick production: Solid waste management in tanneries

Abstract

In leather processing, the generation of buffing dust is an indispensable solid waste. It contains chromium, synthetic oil, dyestuffs, and tanning agents. Management of buffing dust has become a great challenge for the leather industry. This study aims to use buffing dust in brick production and examine the effects of incorporating buffing dust into the physicomechanical, environmental, and morphological properties of produced bricks. In this experiment, bricks were produced conventionally by mixing buffing dust in different ratios ranging from 0% to 12% (wt.) with the clay, and the bricks were fired in a kiln at 1000 °C. Results indicate that 4% buffing dust incorporated bricks showed the maximum compressive strength (12.02 MPa), as well as other engineering properties - water absorption, weight loss on ignition, area shrinkage, bulk density, efflorescence test results - were also in the acceptable range according to ASTM and Bangladesh Standards. Scanning Electron Microscope images imply that buffing dust played an important role in the structure of fired bricks. The NEN 7345 and TCLP leaching tests of fired bricks showed that the leached amount of heavy metals was insignificant and far below the permissible limit. Thus using buffing dust incorporated bricks is quite feasible and will reduce environmental pollution as well.