Fluoride Removal and Recovery from Groundwater Using an Integrated Reverse Osmosis–Membrane Crystallization Process

Elevated fluoride levels in drinking water pose a significant health risk for communities relying on groundwater in the Ethiopian Central Rift Valley. This study aims at characterizing real groundwater samples from the Ethiopian Central Rift Valley and evaluating the performance of an integrated mem...

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Main Authors: Wuhib Zeine Ousman, Esayas Alemayehu, Patricia Luis
Format: Article
Language:English
Published: MDPI AG 2025-05-01
Series:Clean Technologies
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Online Access:https://www.mdpi.com/2571-8797/7/2/40
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author Wuhib Zeine Ousman
Esayas Alemayehu
Patricia Luis
author_facet Wuhib Zeine Ousman
Esayas Alemayehu
Patricia Luis
author_sort Wuhib Zeine Ousman
collection DOAJ
description Elevated fluoride levels in drinking water pose a significant health risk for communities relying on groundwater in the Ethiopian Central Rift Valley. This study aims at characterizing real groundwater samples from the Ethiopian Central Rift Valley and evaluating the performance of an integrated membrane process based on reverse osmosis (RO) and membrane crystallization (MCr) for fluoride removal and its recovery as mixed fluoride salts. Groundwater analysis revealed fluoride concentrations of 20.8 mgL<sup>−1</sup> at the Meki-01 site and 22.7 mgL<sup>−1</sup> at the Meki-02 site, both exceeding the WHO guideline of 1.5 mgL<sup>−1</sup>. In addition, total dissolved solids exceeded 1000 mgL<sup>−1</sup> at both sites, classifying the water as brackish. A commercial RO membrane demonstrated excellent fluoride and ion rejection, with fluoride removal rates exceeding 99%. The total dissolved solids (TDS) removal efficiency reached 89%. The mean water permeability of the membrane was 4.52 Lm<sup>−2</sup>h<sup>−1</sup>bar<sup>−1</sup>. The retentate produced in the RO unit reached a concentration of 70 mgL<sup>−1</sup>, which was then treated using osmotic membrane distillation–crystallization (OMD-Cr) and/or vacuum membrane crystallization (VM-Cr). This process facilitated the recovery of mixed salts while achieving an almost zero-liquid discharge. The study confirms the successful removal of fluoride and its recovery as mixed salt, along with the recovery of water in an environmentally friendly and manageable way.
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spelling doaj-art-7253106451ad4dc2a3d0ba3a664b8a792025-08-20T03:27:23ZengMDPI AGClean Technologies2571-87972025-05-01724010.3390/cleantechnol7020040Fluoride Removal and Recovery from Groundwater Using an Integrated Reverse Osmosis–Membrane Crystallization ProcessWuhib Zeine Ousman0Esayas Alemayehu1Patricia Luis2Jimma Institute of Technology, Jimma University, Jimma P.O. Box 378, EthiopiaJimma Institute of Technology, Jimma University, Jimma P.O. Box 378, EthiopiaMaterials & Process Engineering (iMMC-IMAP), UCLouvain, Place Sainte Barbe 2, B-1348 Louvain-la-Neuve, BelgiumElevated fluoride levels in drinking water pose a significant health risk for communities relying on groundwater in the Ethiopian Central Rift Valley. This study aims at characterizing real groundwater samples from the Ethiopian Central Rift Valley and evaluating the performance of an integrated membrane process based on reverse osmosis (RO) and membrane crystallization (MCr) for fluoride removal and its recovery as mixed fluoride salts. Groundwater analysis revealed fluoride concentrations of 20.8 mgL<sup>−1</sup> at the Meki-01 site and 22.7 mgL<sup>−1</sup> at the Meki-02 site, both exceeding the WHO guideline of 1.5 mgL<sup>−1</sup>. In addition, total dissolved solids exceeded 1000 mgL<sup>−1</sup> at both sites, classifying the water as brackish. A commercial RO membrane demonstrated excellent fluoride and ion rejection, with fluoride removal rates exceeding 99%. The total dissolved solids (TDS) removal efficiency reached 89%. The mean water permeability of the membrane was 4.52 Lm<sup>−2</sup>h<sup>−1</sup>bar<sup>−1</sup>. The retentate produced in the RO unit reached a concentration of 70 mgL<sup>−1</sup>, which was then treated using osmotic membrane distillation–crystallization (OMD-Cr) and/or vacuum membrane crystallization (VM-Cr). This process facilitated the recovery of mixed salts while achieving an almost zero-liquid discharge. The study confirms the successful removal of fluoride and its recovery as mixed salt, along with the recovery of water in an environmentally friendly and manageable way.https://www.mdpi.com/2571-8797/7/2/40fluoride removalfluoride recoveryphysicochemical analysisreverse osmosismembrane crystallization
spellingShingle Wuhib Zeine Ousman
Esayas Alemayehu
Patricia Luis
Fluoride Removal and Recovery from Groundwater Using an Integrated Reverse Osmosis–Membrane Crystallization Process
Clean Technologies
fluoride removal
fluoride recovery
physicochemical analysis
reverse osmosis
membrane crystallization
title Fluoride Removal and Recovery from Groundwater Using an Integrated Reverse Osmosis–Membrane Crystallization Process
title_full Fluoride Removal and Recovery from Groundwater Using an Integrated Reverse Osmosis–Membrane Crystallization Process
title_fullStr Fluoride Removal and Recovery from Groundwater Using an Integrated Reverse Osmosis–Membrane Crystallization Process
title_full_unstemmed Fluoride Removal and Recovery from Groundwater Using an Integrated Reverse Osmosis–Membrane Crystallization Process
title_short Fluoride Removal and Recovery from Groundwater Using an Integrated Reverse Osmosis–Membrane Crystallization Process
title_sort fluoride removal and recovery from groundwater using an integrated reverse osmosis membrane crystallization process
topic fluoride removal
fluoride recovery
physicochemical analysis
reverse osmosis
membrane crystallization
url https://www.mdpi.com/2571-8797/7/2/40
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AT esayasalemayehu fluorideremovalandrecoveryfromgroundwaterusinganintegratedreverseosmosismembranecrystallizationprocess
AT patricialuis fluorideremovalandrecoveryfromgroundwaterusinganintegratedreverseosmosismembranecrystallizationprocess