title: Designing metallic iron based water filters: Light from methylene blue discoloration.
abstract: Available water filtration systems containing metallic iron (Fe(0) filters) are pragmatically designed. There is a lack of sound design criteria to exploit the full potential of Fe(0) filters. A science-based design relies on valuable information on processes within a Fe(0) filter, including chemical reactions, hydrodynamics and their relation to the performance of the filter. The aim of this study was to establish a simple method to evaluate the initial performance of Fe(0) filters. The differential adsorptive affinity of methylene blue (MB) onto sand and iron oxide is exploited to characterize the evolution of a Fe(0)/sand system using the pure sand system as operational reference. Five systems were investigated for more than 70 days: pure sand, pure Fe(0), Fe(0)/sand, Fe(0)/pumice and Fe(0)/sand/pumice. Individual systems were characterized by the extent of changes in pH value, iron breakthrough, MB breakthrough and hydraulic conductivity. Results showed that for MB discoloration (i) pure sand was the most efficient system, (ii) hybrid systems were more sustainable than the pure Fe(0) system, and (iii) the pores of used pumice are poorly interconnected. Characterizing the initial reactivity of Fe(0) filters using MB discoloration has introduced a powerful tool for the exploration of various aspects of filter design.
authors.affiliation: Laboratory of Industrial and Pollution Chemistry, Department of Applied Chemistry, ENSAI, University of Ngaoundéré, BP 455 Ngaoundéré, Cameroon; Université Paris-Est, Laboratoire Navier (UMR CNRS - IFSTTAR - ENPC), IFSTTAR, 6-8, av. Bd. Pascal, F-77455 Marne-la-Vallée, France.
authors.forename: B D
authors.initials: BD
authors.lastname: Btatkeu-K
authors.affiliation: Laboratory of Industrial and Pollution Chemistry, Department of Applied Chemistry, ENSAI, University of Ngaoundéré, BP 455 Ngaoundéré, Cameroon.
authors.forename: J B
authors.initials: JB
authors.lastname: Tchatchueng
authors.affiliation: Angewandte Geologie, Universität Göttingen, Goldschmidtstraße 3, D-37077 Göttingen, Germany; Kultur und Nachhaltige Entwicklung CDD e.V., Postfach 1502, D-37005 Göttingen, Germany; Comité Afro-européen, Avenue Léopold II, 41, 5000 Namur, Belgium. Electronic address: cnoubac@gwdg.de.
authors.forename: C
authors.initials: C
authors.lastname: Noubactep
authors.affiliation: Université Paris-Est, Laboratoire Navier (UMR CNRS - IFSTTAR - ENPC), IFSTTAR, 6-8, av. Bd. Pascal, F-77455 Marne-la-Vallée, France.
authors.forename: S
authors.initials: S
authors.lastname: Caré
mesh_terms: D000327:Adsorption; D005290:Ferric Compounds / Q000737:chemistry; D005374:Filtration / Q000295:instrumentation* / Q000379:methods; D007501:Iron / Q000737:chemistry*; D008751:Methylene Blue / Q000032:analysis / Q000737:chemistry; D017640:Silicates / Q000737:chemistry; D012822:Silicon Dioxide / Q000737:chemistry; D013053:Spectrophotometry; D014867:Water / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000032:analysis*; D018508:Water Purification / Q000295:instrumentation / Q000379:methods*
chemical_list: D005290:Ferric Compounds; D017640:Silicates; D014874:Water Pollutants, Chemical; D014867:Water; C000499:ferric oxide; D012822:Silicon Dioxide; D007501:Iron; C005144:pumice; D008751:Methylene Blue
keywords: Contaminant removal; Frugal innovation; Selective adsorption; Water filtration; Zero-valent iron