Coagulation/flocculation/sedimentation applied to marble processing wastewater treatment

Abstract

In the current work, the application of chemical coagulation/flocculation/sedimentation, an established and low cost method, to marble processing wastewater treatment is studied, and the optimum conditions for the maximum solid waste removal are investigated. The environmental impact from the operation of a modern marble processing plant is actually important, due to the consumption of high amounts of water resulting in the production of high effluent volumes, and therefore particular efforts are made for the efficient wastewater treatment in order to recover and reuse the effluents of the process, and avoid uncontrolled discharge and disposal of solid residue from the primary wastewater treatment. For that purpose, hydrated metal salts including Al 2 (SO 4) 3 18H 2 O, FeCl 3 6H 2 O and FeSO 4 7H 2 O were examined for their turbidity removal capacity under various dosages and studied in relation to the wastewater pH and electrical conductivity. Jar test results showed that FeCl 3 6H 2 O presented the highest turbidity removal ability at doses of about 0.375g/L, while the poorest coagulation/flocculation potential was found for FeSO 4 7H 2 O. The findings of this study are expected to contribute to the preparation of a strategic plan for the integrated management of marble processing operations with a lower environmental footprint.