Use of electroplating sludge in production of fired clay bricks: Characterization and environmental risk evaluation

A noticeable amount of electroplating sludge, resulting from electroplating and surface treatment industries, may pose serious threat to human health and surrounding environmental without safe treatment. This study examined the feasibility of preparing the fired clay bricks with the addition of electroplating sludge, by evaluating the physical properties and environmental risk of the prepared clay bricks. It was found that the introduction of electroplating sludge reduced the bulk density and compressive strength, and increased the mass loss, linear shrinkage, porosity ratio and water absorption. It was observed compressive strength declined from 23.5 to 15.5 MPa, and water absorption increased from 2.7 to 3.46% with the addition of electroplating sludge up to 10 wt%. Though the introduction of electroplating sludge influenced the mechanical and physical properties, these parameters are enough according to the values required by the standards. Prolonged leaching experiments up to 20 days were carried out to test the whole bricks and brick powder. The results clearly presented the optimum substitution amount of electroplating sludge in clay bricks was less than 8 wt%. Besides, leaching test suggested that though the prepared bricks with the addition of electroplating sludge were abandoned in the surrounding environmental after the use period, the leaching risks of heavy metals released from the bricks still can be reduced substantially, because heavy metals might be incorporated into stable mineral structure during firing process. These results suggested use of electroplating sludge in the production of fired clay bricks or ceramics might be a alternative and reliable method for the disposal of electroplating sludge.