Immobilization of zinc and lead from wastes using simple and fibre‐reinforced lime‐pozzolana admixtures

Abstract

Immobilization techniques which include chemical fixation and physical encapsulation are used for treatment and disposal of toxic industrial wastes in order to minimise the hazards to the environment. Heavy metal ions are found in the industrial waste waters and sludges of many vital industries. Most of these heavy metal ions, when present in appreciable quantities may be toxic to vegetable, aquatic, animal and human life. The present paper deals with the investigations on the immobilization of Zn and Pb present in the waste sludge in simple and fibre‐reinforced lime‐fly ash admixture cubes. The techniques studied include fixation, coating with sodium silicate solution and encapsulation procedures. The fibre additives studied include glasswool, steelwool and suqarcane‐bagasse, The results indicate that excellent immobilization efficiency can be achieved by encapsulating the heavy metal hydroxide sludge in simple as well as fibre‐reinforced lime‐fly ash admixtures as per the procedure now developed. Fixation and coating techniques also yielded encouraging results for the immobilization of heavy metal ions although they are not as efficient as the encapsulation technique. Fibre‐additives help in improving the structural strength of lime‐fly ash cubes.

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