Fe0/H2O Filtration Systems for Decentralized Safe Drinking Water: Where to from Here?

Nanseu‐Njiki, Charles Péguy; Gwenzi, Willis; Pengou, Martin; Rahman, Mohammad Azizur; Noubactep, Chicgoua

doi:10.3390/w11030429

Cited by 25 publications

(26 citation statements)

References 143 publications

(349 reference statements)

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“…Once a significant number of materials differing in their k Phen values are tested in such long-term experiments, it will be possible to reliably recommend selected ones for the site-specific design of field Fe 0 /H 2 O systems. In other words, the data provided herein are a clear starting point for the design of future laboratory, pilot, and field-scale studies for the design of the next generation Fe 0 remediation systems to achieve the United Nations Sustainable Development Goals (UN SDGs) [18]. Further work should also use other affordable approaches like the methylene blue method (MB method) [69] to quickly access the impact of various parameters of the system efficiency.…”

Section: Discussionmentioning

confidence: 99%

“…Therefore, k Phen values provide a reliable and confident parameter to characterize reactive Fe 0 materials. Following the roadmap of [18], it is time to build a significant k Phen database for available Fe 0 materials to prepare their systematic testing in long-term column experiments. Once a significant number of materials differing in their k Phen values are tested in such long-term experiments, it will be possible to reliably recommend selected ones for the site-specific design of field Fe 0 /H 2 O systems.…”

Section: Discussionmentioning

confidence: 99%

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A Novel and Facile Method to Characterize the Suitability of Metallic Iron for Water Treatment

Lufingo

Ndé-Tchoupé

et al. 2019

Water

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Metallic iron (Fe0) materials have been industrially used for water treatment since the 1850s. There are still many fundamental challenges in affordably and reliably characterizing the Fe0 intrinsic reactivity. From the available methods, the one using Fe0 dissolution in ethylenediaminetetraacetic acid (EDTA—2 mM) was demonstrated the most applicable as it uses only four affordable chemicals: Ascorbic acid, an ascorbate salt, EDTA and 1,10-Phenanthroline (Phen). A careful look at these chemicals reveals that EDTA and Phen are complexing agents for dissolved iron species. Fe3-EDTA is very stable and difficult to destabilize; ascorbic acid is one of the few appropriate reducing agents, therefore. On the other hand, the Fe2-Phen complex is so stable that oxidation by dissolved O2 is not possible. This article positively tests Fe0 (0.1 g) dissolution in 2 mM Phen (50 mL) as a characterization tool for the intrinsic reactivity, using 9 commercial steel wool (Fe0 SW) specimens as probe materials. The results are compared with those obtained by the EDTA method. The apparent iron dissolution rate in EDTA (kEDTA) and in Phen (kPhen) were such that 0.53 ≤ kEDTA (μg h−1) ≤ 4.81 and 0.07 ≤ kPhen (μg h−1) ≤ 1.30. Higher kEDTA values, relative to kPhen, are a reflection of disturbing Fe3 species originating from Fe2 oxidation by dissolved O2 and dissolution of iron corrosion products. It appears that the Phen method considers only the forward dissolution of Fe0. The Phen method is reliable and represents the most affordable approach for characterizing the suitability of Fe0 for water treatment.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

A Novel and Facile Method to Characterize the Suitability of Metallic Iron for Water Treatment

Lufingo

Ndé-Tchoupé

et al. 2019

Water

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“…Required experiments should last for long times (at least one year) as there is no way to reproduce accelerated iron corrosion. The authors have been advocating for the past decade that designing such filters will universally provide safe drinking water to low-income communities worldwide [82][83][84].…”

Section: Significance Of the Resultsmentioning

confidence: 99%

Steel Wool for Water Treatment: Intrinsic Reactivity and Defluoridation Efficiency

Hildebrant¹,

Ndé-Tchoupé

Lufingo

et al. 2020

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Studies were undertaken to characterize the intrinsic reactivity of Fe0-bearing steel wool (Fe0 SW) materials using the ethylenediaminetetraacetate method (EDTA test). A 2 mM Na2-EDTA solution was used in batch and column leaching experiments. A total of 15 Fe0 SW specimens and one granular iron (GI) were tested in batch experiments. Column experiments were performed with four Fe0 SW of the same grade but from various suppliers and the GI. The conventional EDTA test (0.100 g Fe0, 50 mL EDTA, 96 h) protocol was modified in two manners: (i) Decreasing the experimental duration (down to 24 h) and (ii) decreasing the Fe0 mass (down to 0.01 g). Column leaching studies involved glass columns filled to 1/4 with sand, on top of which 0.50 g of Fe0 was placed. Columns were daily gravity fed with EDTA and effluent analyzed for Fe concentration. Selected reactive Fe0 SW specimens were additionally investigated for discoloration efficiency of methylene blue (MB) in shaken batch experiments (75 rpm) for two and eight weeks. The last series of experiments tested six selected Fe0 SW for water defluoridation in Fe0/sand columns. Results showed that (i) the modifications of the conventional EDTA test enabled a better characterization of Fe0 SW; (ii) after 53 leaching events the Fe0 SW showing the best kEDTA value released the lowest amount of iron; (iii) all Fe0 specimens were efficient at discoloring cationic MB after eight weeks; (iv) limited water defluoridation by all six Fe0 SW was documented. Fluoride removal in the column systems appears to be a viable tool to characterize the Fe0 long-term corrosion kinetics. Further research should include correlation of the intrinsic reactivity of SW specimens with their efficiency at removing different contaminants in water.

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“…On the other hand, the long-term kinetics of the generation of contaminant scavengers (iron corrosion products) is yet to be properly addressed. This knowledge gap will soon be filled, and a roadmap to achieve this was presented in Nanseu-Njiki et al [4].…”

mentioning

confidence: 99%

“…Nanseu-Njiki et al [4] is a timely paper focusing on decentralized safe drinking water provision using Fe 0 -based systems. The authors excellently resolved the prevailing confusion that has strongly hampered the design of efficient and sustainable Fe 0 filters for drinking water.…”

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confidence: 99%

Editorial for the Special Issue: Filters in Drinking Water Treatment

Noubactep¹

2019

Water

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Slow sand filters were first used for safe drinking water provision during the 19th century. The technology has been gradually improved and utilized at several scales. Based on their intrinsic limitations other filtration systems have been developed, including membrane technologies. The universal applicability of filtration in drinking water supply makes filters a device of choice to facilitate the achievement of the UN Sustainable Development Goals (‘drinking water for all by 2030’). Available strategies to rationally design efficient and sustainable water filters are scattered in the literature and are difficult to access and evaluate by starting researchers. The present Special Issue summarizes knowledge on two key filtration systems for drinking water supply: (i) membrane technology and (ii) metallic iron based filters. The five (5) accepted articles are being briefly presented herein.

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Fe0/H2O Filtration Systems for Decentralized Safe Drinking Water: Where to from Here?

Cited by 25 publications

References 143 publications

A Novel and Facile Method to Characterize the Suitability of Metallic Iron for Water Treatment

A Novel and Facile Method to Characterize the Suitability of Metallic Iron for Water Treatment

Steel Wool for Water Treatment: Intrinsic Reactivity and Defluoridation Efficiency

Editorial for the Special Issue: Filters in Drinking Water Treatment

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