{"id":91,"date":"2011-05-30T08:11:19","date_gmt":"2011-05-30T08:11:19","guid":{"rendered":"http:\/\/africa-and-science.com\/?p=91"},"modified":"2011-05-30T10:34:10","modified_gmt":"2011-05-30T10:34:10","slug":"dr-chicgoua-noubactep-available-in-english-and-in-german","status":"publish","type":"post","link":"https:\/\/africa-and-science.com\/?p=91","title":{"rendered":"Dr. Chicgoua Noubactep"},"content":{"rendered":"

On February 16th, 2011, Dr. Chicgoua Noubactep <\/strong>defended his Habilitation Thesis, at the University of G\u00f6ttingen (Germany). His research was on \u00abMetallic iron for\u00a0safe drinking water production\u00bb. <\/span><\/strong>(available in English and German)<\/span><\/span><\/p>\n

Abstract<\/strong><\/p>\n

Scientific progress\u00a0is in\u00a0normally a permanent accumulation of experimental observations and data. However, pure accumulation is of limited value. A profound look behind the data is necessary to recognize relations between apparently remote observations and express these relations in universally valid concepts and models. Usually, such concepts are cornerstones for further scientific progress.<\/p>\n

Based on the above premise and the experimental evidence that metallic iron (Fe0) do remove more substances or substance classes from\u00a0aqueous solutions\u00a0than could be predicted for a\u00a0reducing agent\u00a0(Fe0), the objective of the present work was to critically review the literature on \u201cwater treatment\u00a0with Fe0\u201d and discuss the consequences for the further development of the technology of \u201cusing Fe0\u00a0for water treatment\u201d.<\/p>\n

The first observation was that the approach to investigate processes in Fe0\/H2O systems has been more pragmatic than systematic. In fact, iron walls have first been reported to effectively degrade solvents in groundwater. Subsequently, the ability of Fe0\u00a0to treat other contaminants has been evaluated on a case-by-case basis. Quantitative removal of non-reducible species, oxidable species and species without redox properties has been reported as well. Therefore, the concept considering Fe0\u00a0as a reducing agent has been questioned and proven inconsistent. A new concept has been introduced and validated which considers adsorption (and adsorptive size exclusion in column studies), and co-precipitation as fundamental contaminant removal mechanisms. Because removed contaminants are enmeshed in the matrix of transforming iron corrosion products, they are necessarily long-term stable under experimental conditions. Thus, Fe0\u00a0is a universal material for water treatment and in particular for safe drinking water production.<\/p>\n

Next to the profound understanding of the mechanism of contaminant removal in packed Fe0\u00a0beds, the volumetric expansive nature of iron oxidative dissolution at pH > 4.5 was properly considered. The result was the suggestion of Fe0\u00a0volumetric proportions between 30 and 60 % for safe drinking water production at household level. Ideally, Fe0\u00a0is mixed with porous inert materials which sustain the reactivity of Fe0\u00a0by storing in-situ generated\u00a0iron hydroxides.<\/p>\n

The efficiency of a Fe0\u00a0bed mostly depends on: (i) the intrinsic reactivity of used Fe0, (ii) the thickness of the bed, and the water flow rate (or the\u00a0residence time\u00a0within the bed). Future experimental works should be focused on characterizing the intrinsic reactivity of potential affordable materials. It can be emphasized that Fe0\u00a0beds will allow for the provision of household and remote small communities with\u00a0safe drinking water.<\/p>\n

Zusammenfassung<\/p>\n

Die generelle Eignung von Eisenwerkstoffen (Fe0) zur Schadstoffentfernung aus der w\u00e4ssrigen Phase wurde konzeptionell nachgewiesen. Das Arbeitziel bestand darin, sich widersprechende Beobachtungen und Ergebnisse aus 15 Jahren Forschung zum Thema \u201eWasserbehandlung mit metallischem Eisen\u201c kritisch zu betrachten.\u00a0Aus\u00a0dieser kritischen Betrachtung sollten Beziehungen zwischen scheinbar zusammenhanglosen Erscheinungen erkennt werden. Diese Beziehungen sollten dann in ein einfaches allgemeing\u00fcltiges Konzept ausgedr\u00fcckt werden. Das entstandene Konzept sollte die Grundlage f\u00fcr weitere Fortschritte sein.<\/p>\n

Ausgehend von der Feststellung, dass sowohl reduzierbare und oxidierbare w\u00e4ssrige Verbindungen, als auch Verbindungen ohne Redox-Eigenschaften quantitativ durch Anwesenheit von\u00a0Fe0entfernt werden, besagt das in dieser Arbeit entwickelte Konzept, dass keine chemische Umwandlung (Oxidation oder Reduktion) der Grundvorgang f\u00fcr die Schadstoffentfernung sein kann. Folglich werden Schadstoffe haupts\u00e4chlich durch\u00a0Adsorption\u00a0und Mitf\u00e4llung aus der w\u00e4ssrigen Phase entfernt. Da die entfernten Schadstoffe in der Masse der Eisenkorrosionsprodukte eingekapselt werden d\u00fcrften, sind sie langzeitstabil, unabh\u00e4ngig davon, ob sie chemisch umgewandelt wurden oder nicht. In Festbetten kommt einen adsorptiven Gr\u00f6\u00dfenausschluss (\u201eadsorptive size exclusion\u201c) als R\u00fcckhaltmechanismus hinzu. Somit ist Fe0\u00a0ein Universalmaterial f\u00fcr die Wasserbehandlung: Trinkwasseraufbereitung, Abwasserbehandlung und Grundwassersanierung.<\/p>\n

Als Ergebnis wird Fe0-Festbett f\u00fcr Wasserbehandlung empfohlen. Fe0-Festbett sollen zwischen 30 und 60 % Volumenanteil Fe0\u00a0enthalten. Sand und por\u00f6se Materialien werden als F\u00fcllmaterialien vorgeschlagen, um eine Langzeitreaktivit\u00e4t zu gew\u00e4hrleisten. Da der Gesamtvorgang der Eisenkorrosion f\u00fcr die Schadstoffentfernung sorgt, ist die Flie\u00dfgeschwindigkeit des Wassers in Fe0-Festbett und die Bettst\u00e4rke gezielt zu bestimmen. Zuk\u00fcnftige praktische Arbeiten m\u00fcssen sich der Charakterisierung der Fe0-Materialien widmen. Fe0-Festbette eignen sich insbesondere f\u00fcr Wasserversorgung von kleinen Gemeinden oder einzelne Haushalte.\/.<\/p>\n","protected":false},"excerpt":{"rendered":"

On February 16th, 2011, Dr. Chicgoua Noubactep defended his Habilitation Thesis, at the University of G\u00f6ttingen (Germany). His research was on \u00abMetallic iron for\u00a0safe drinking water production\u00bb. (available in English and German)<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[6],"tags":[],"class_list":["post-91","post","type-post","status-publish","format-standard","hentry","category-master-and-phd-theses"],"_links":{"self":[{"href":"https:\/\/africa-and-science.com\/index.php?rest_route=\/wp\/v2\/posts\/91"}],"collection":[{"href":"https:\/\/africa-and-science.com\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/africa-and-science.com\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/africa-and-science.com\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/africa-and-science.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=91"}],"version-history":[{"count":8,"href":"https:\/\/africa-and-science.com\/index.php?rest_route=\/wp\/v2\/posts\/91\/revisions"}],"predecessor-version":[{"id":94,"href":"https:\/\/africa-and-science.com\/index.php?rest_route=\/wp\/v2\/posts\/91\/revisions\/94"}],"wp:attachment":[{"href":"https:\/\/africa-and-science.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=91"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/africa-and-science.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=91"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/africa-and-science.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=91"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}