Chrome (VI) Removal from Wastewater Using Water Treatment Plant Sludge as an Adsorbent

Abstract

Background: The extensive use of chromium in industries such as electroplating, steel production, wood preservation, and leather tanning can result in release of chromium-containing effluents. Hexavalent chromium in the environment has been often harmful and it should be treated before releasing into the environment. So far various wastewater treatment techniques have been used to remove heavy metals from industrial wastewater. Due to this, an adsorbent with high removal capacity, low cost, and easy accessibility will be a choice for industrial wastewater treatment option. This study aimed at removing chromium from wastewater using low-cost alum-based water treatment plant sludge, as an adsorbent.
Methods: The study was conducted on the removal of Cr (VI) by alum-based water treatment sludge through batch adsorption experimental study. Response surface methodology was applied in batch-wise experiments to evaluate the process viable, Cr (VI) concentration, pH, adsorbent dose, time, and temperature.
Results: Chrome (VI) concentration and pH increase were found to decrease chrome removal, while adsorbent dose
and shaking time increase, increased chrome removal. Cr (IV) concentration with pH shows that maximum chrome removal of 95.62% was obtained at Cr (IV) concentration of 2.4mg/l and pH 2.45, while the interaction of Cr (IV) concentration and adsorbent dose shows, 97.06% chrome removal was obtained at a chrome concentration of 3.3mg/L and adsorbent dose of 6.3g.
Conclusion: Alum-based water treatment sludge is a suitable material from which a low-cost adsorbent for removal of Cr (VI) can be developed.