Chromium removal from electroplating waste using palm oil fuel ash

Abstract

© 2016, ICE Publishing. All rights reserved. This laboratory-scale study investigated the use of palm oil fuel ash (POFA) as an adsorbent to remove hexavalent chromium (Cr) from electroplating waste water as well as the potential of POFA as an admixture in a cement-based stabilisation and solidification (S/S) process. Results indicated that POFA was very effective in removing chromium, exceeding the 99·5% level in all experimental runs. Overall, adsorption improved as the POFA particle size decreased and the concentration of the reagent (ferrous chloride) added increased. Regarding the S/S tests, both the compressive strength and the chromium leachability of the solidified samples were found to be optimal at the lower explored ranges of POFA and ash-sludge mix ratio (0·25/0·25), water-to-solids ratio (0·7) and POFA particle size (<75 µm). Furthermore, both the compressive strength and the chromium leaching concentration of the solidified sludge samples were much lower than 5 mg/l (under most conditions tested), which satisfied the required Thai standards, either for application as a construction material or for secure landfill disposal.