Affiliations 

  • 1 Department of Environmental Engineering, School of Civil Engineering, Faculty of Engineering, Universiti Teknologi Malaysia, 81300, Johor Bahru, Malaysia
  • 2 Department of Environmental Engineering, School of Civil Engineering, Faculty of Engineering, Universiti Teknologi Malaysia, 81300, Johor Bahru, Malaysia; Centre for Environmental Sustainability and Water Security (IPASA), Research Institute for Environmental Sustainability, Universiti Teknologi Malaysia, 81310, Johor Bahru, Malaysia. Electronic address: mfadhil@utm.my
  • 3 Department of Civil and Environmental Engineering, Seoul National University, Seoul, Republic of Korea
  • 4 Department of Structure and Materials, School of Civil Engineering, Faculty of Engineering, Universiti Teknologi Malaysia, 81310, Johor Bahru, Johor, Malaysia
  • 5 Engineering Department, UTM Razak School of Engineering & Advanced, Universiti Teknologi Malaysia, Malaysia
  • 6 Office of Deputy Vice-Chancellor (Development), Universiti Teknologi Malaysia, 81300, Johor Bahru, Malaysia
J Environ Manage, 2018 Dec 15;228:13-19.
PMID: 30212670 DOI: 10.1016/j.jenvman.2018.09.008

Abstract

For decades, water treatment plants in Malaysia have widely employed aluminium-based coagulant for the removal of colloidal particles in surface water. This generates huge amount of by-product, known as sludge that is either reused for land applications or disposed to landfills. As sludge contains high concentration of aluminium, both can pose severe environmental issues. Therefore, this study explored the potential to recover aluminium from water treatment sludge using acid leaching process. The evaluation of aluminium recovery efficiency was conducted in two phases. The first phase used the one factor at a time (OFAT) approach to study the effects of acid concentration, solid to liquid ratio, temperature and heating time. Meanwhile, second phase emphasized on the optimization of aluminium recovery using Response Surface Methodology (RSM). OFAT results indicated that aluminium recovery increased with the rising temperature and heating time. Acid concentration and solid to liquid ratio, however, showed an initial increment followed by reduction of recovery with increasing concentration and ratio. Due to the solidification of sludge when acid concentration exceeded 4 M, this variable was fixed in the optimization study. RSM predicted that aluminium recovery can achieve 70.3% at optimal values of 4 M, 20.9%, 90 °C and 4.4 h of acid concentration, solid to liquid ratio, temperature and heating time, respectively. Experimental validation demonstrated a recovery of 68.8 ± 0.3%. The small discrepancy of 2.2 ± 0.4% between predicted and validated recovery suggests that RSM was a suitable tool in optimizing aluminium recovery conditions for water treatment sludge.

* Title and MeSH Headings from MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.