Application of nanofiltration for Rare Earth Elements recovery from coal fly ash leachate: Performance and cost evaluation

Borte Kose Mutlu, Beatrice Cantoni, Andrea Turolla, Manuela Antonelli, Heileen Hsu-Kim, Mark R. Wiesner*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

75 Citations (Scopus)


This work evaluated nanofiltration (NF) as a potential step in the recovery process of Rare Earth Elements (REEs) from leachates of coal combustion fly ashes. A pre-treatment step, by pH adjustment and microfiltration (MF), has been studied to separate REEs by major elements. The individual and combined effects of applied pressure (12-24 bar) and NF feed acidity (pH 1.5-3.5) on rejection of six critical REEs and permeate flux have been investigated via response surface methodology (RSM). The resulting model equations were used to develop a cost model for the recovery chain, in order to select the optimum NF operating conditions. The optimization of the REE recovery chain, including pre-treatment and NF, was done with respect to the objective of maximizing the difference between NF concentrate economic value and treatment cost. NF with an appropriate MF pre-treatment has been effective in concentrating REEs from fly ash leachate, reaching the maximum potential gain at the optimum operating conditions of 12 bar and pH 3.5.

Original languageEnglish
Pages (from-to)309-317
Number of pages9
JournalChemical Engineering Journal
Publication statusPublished - 1 Oct 2018
Externally publishedYes

Bibliographical note

Publisher Copyright:
© 2018 Elsevier B.V.


The research was supported by the U.S. Department of Energy under the Project No. DE-FE0026952 and the U.S. National Science Foundation Environmental Engineering program (CBET-1510965). The financial support for Dr. Borte Kose-Mutlu was provided by TUBITAK 2219-International Postdoctoral Research Fellowship Program. The authors thank Ross Taggart for providing coal fly ash leachate, Prof. Dr. Dincer Topacık National Research Center on Membrane Technologies (MEM-TEK) for ZP measurements, and David Dickerson for supplying NP010 and NP030 membranes.

FundersFunder number
National Science Foundation Environmental Engineering ProgramCBET-1510965
U.S. Department of EnergyDE-FE0026952


    • Coal combustion residues
    • Cost model
    • Critical elements
    • Membrane technology
    • Response surface methodology


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