Improved bauxite residue dealkalization by combination of aerated washing and electrodialysis

Yaxian Zhang; Qi Shi; Muxi Luo; Hongtao Wang; Xuejiao Qi; Chia-Hung Hou; Fengting Li; Zisheng Ai; Jose Tacares Araruna Junior

doi:10.1016/j.jhazmat.2018.10.023

Improved bauxite residue dealkalization by combination of aerated washing and electrodialysis

J Hazard Mater. 2019 Feb 15:364:682-690. doi: 10.1016/j.jhazmat.2018.10.023. Epub 2018 Oct 15.

Authors

Yaxian Zhang¹, Qi Shi², Muxi Luo², Hongtao Wang³, Xuejiao Qi², Chia-Hung Hou⁴, Fengting Li², Zisheng Ai⁵, Jose Tacares Araruna Junior⁶

Affiliations

¹ State Key Laboratory of Pollution Control and Resource Reuse, Key Laboratory of Yangtze River Water Environment, Ministry of Education, College of Environmental Science and Engineering, UNEP-TONGJI Institute of Environment for Sustainable Development, Tongji University, Siping Rd 1239, Shanghai, 200092, PR China; Shanghai Institute of Pollution Control and Ecological Security, Tongji University, Siping Rd 1239, Shanghai, 200092, PR China; International Joint Research Center for Sustainable Urban Water System, Tongji University, Siping Rd 1239, Shanghai, 200092, PR China.
² State Key Laboratory of Pollution Control and Resource Reuse, Key Laboratory of Yangtze River Water Environment, Ministry of Education, College of Environmental Science and Engineering, UNEP-TONGJI Institute of Environment for Sustainable Development, Tongji University, Siping Rd 1239, Shanghai, 200092, PR China; Shanghai Institute of Pollution Control and Ecological Security, Tongji University, Siping Rd 1239, Shanghai, 200092, PR China.
³ State Key Laboratory of Pollution Control and Resource Reuse, Key Laboratory of Yangtze River Water Environment, Ministry of Education, College of Environmental Science and Engineering, UNEP-TONGJI Institute of Environment for Sustainable Development, Tongji University, Siping Rd 1239, Shanghai, 200092, PR China; Shanghai Institute of Pollution Control and Ecological Security, Tongji University, Siping Rd 1239, Shanghai, 200092, PR China; International Joint Research Center for Sustainable Urban Water System, Tongji University, Siping Rd 1239, Shanghai, 200092, PR China. Electronic address: hongtao@tongji.edu.cn.
⁴ Graduate Institute of Environmental Engineering, National Taiwan University, Taipei, 10617, Taiwan, ROC. Electronic address: chiahunghou@ntu.edu.tw.
⁵ Department of Medical Statistics, School of Medicine, Tongji University, 1239 Siping Road, Yangpu District, Shanghai, 200092, PR China.
⁶ Department of Civil and Environmental Engineering, Pontifical Catholic University of Rio de Janeiro, Rio de Janeiro, Brazil.

PMID: 30399551
DOI: 10.1016/j.jhazmat.2018.10.023

Abstract

Bauxite residue, a major by-product of the alumina-producing Bayer process, is a serious environmental pollutant due to its high alkalinity. Here, we reported an operation system designed in our laboratory that included washing and electrodialysis dealkalization systems with aeration pipes. Washing with aeration releases a substantial amount of free alkali and attached alkali into water and increases the dealkalization efficiency. The washing liquid was treated with five steps of batch-mode electrodialysis. The average removal of total dissolved solids (TDS) after the aeration and non-aeration electrodialysis processes were 61.30% and 39.61%, respectively. The average removal of OH^- under aeration conditions was 76.62%, a value that was greater than the value produced under non-aeration conditions (68.48%). This efficiency was also higher than that of some other reports (64.90-68.50%). Aeration decreased the energy consumption to a greater extent than the non-aeration condition. NaOH was recovered in terms of the concentration chamber, and the NaAl(OH)₄ present in the dilution chamber was separated for the electrodialysis treatment. Membrane scaling was generated to a lesser amount under aeration conditions than that of non-aeration conditions, which would improve the dealkalization efficiency. The high repeatability of the experiments was indicated by the intraclass correlation coefficient (P < 0.05).

Keywords: Aeration; Bauxite residue; Dealkalization; Electrodialysis; Membrane.

Publication types

Research Support, Non-U.S. Gov't