Investigating the mechanism of Uranium removal by zerovalent iron

Zerovalent iron (ZVI) has been proposed as a reactive material in permeable in situ walls for groundwater contaminated by metal pollutants. For such pollutants that interact with corrosion products, the determination of the actual mechanism of their removal is very important to predict their stability in the long term. From a study of the effects of pyrite (FeS2) and manganese nodules (MnO2) on the uranium removal potential of a selected ZVI material, a test methodology (FeS2MnO2 method) is suggested to follow the pathway of contaminant removal by ZVI materials. An interpretation of the removal potential of ZVI for uranium in the presence of both additives corroborates coprecipitation with iron corrosion products as the initial removal mechanism for uranium.Keywords: iron, redox reactions, uranium, water treatmentresearc

Elemental iron (Fe0) for better drinking water in rural areas of developing countries

Many of the reasons behind the anthropogenic contamination problems in rural environments of developing countries lie in changes in the traditional way of life and the ignorance on the toxic potential of introduced manufactured products. A generalization trend exists within the international community suggesting that water in developing countries is of poor quality. However, the water quality is rarely analytically determined. Existing potabilization solutions may be prohibitively expensive for the rural populations. Therefore, efficient and affordable technologies are still needed to ameliorate the water quality. In the recent two decades,elemental iron has shown the capacity to remove all possible contaminants (including viruses) from the groundwater. This paper presents a concept to scale down the conventional iron barrier technology to meet the requirements of small communities and households in rural environments worldwide.researc

Integrierte Datenauswertung Hydrogeologie

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Testing the Suitability of Zerovalent Iron Materials for Reactive Walls

Zerovalent iron (ZVI) has been proposed as reactive material in permeable in situ walls for contaminated groundwater. An economically feasible ZVI-based reactive wall requires cheap but efficient iron materials. From an uranium treatability study and results of iron dissolution in 0.002 M EDTA by five selected ZVI materials, it is shown that current research and field implementation is not based on a rational selection of application-specific iron metal sources. An experimental procedure is proposed which could enable a better material characterization. This procedure consists of mixing ZVI materials and reactive additives, including contaminant releasing materials (CRMs), in long-term batch experiments and characterizing the contaminant concentration over the time.Keywords: iron, redox reactions, uranium water, treatmentresearc

The effect of gluconic acid secretion by phosphate-solubilizing Pseudomonas putida bacteria on dissolution of pyromorphite Pb_{5}(PO_{4})_{3}Cl and Pb remobilization

The purpose of this study was to investigate the effect of bacterially produced gluconic acid on the dissolution of pyromorphite and Pb remobilization. Pyromorphite Pb_5(PO_4)_3Cl is formed as a product of the phosphate-induced treatment of Pb-contaminated sites. This very stable mineral greatly decreases the bioavailability of Pb. In this study, bacterial and abiotic batch experiments on the dissolution of pyromorphite were carried out. In the microbial experiments, the mineral was dissolved in the presence of the phosphate solubilizing soil bacterium, Pseudomonas putida. The bacterial growth medium was supplemented with glucose, which under natural conditions can be supplied to microbes via symbiosis with plants. P. putida acquired P from pyromorphite and enhanced its dissolution. Elevated Pb concentrations were observed in the suspensions with bacteria. The bacterial secretion of 16.5 mM gluconic acid played a significant role in Pb remobilization; the pH of the solution dropped down from an initial 7.4 to 3.5. In the abiotic experiments, pyromorphite was dissolved at several concentrations of gluconic acid and at an acidic to neutral pH range. Both acidification and formation of stable Ph-gluconate ligands enhanced the dissolution of pyromorphite and caused Pb remobilization

Pb remobilization by bacterially mediated dissolution of pyromorphite Pb_{5}(PO_{4})_{3}Cl in presence of phosphate-solubilizing Pseudomonas putida

Remediation of lead (Pb)-contaminated sites with phosphate amendments is one of the best studied and cost-effective methods for in situ immobilization. In this treatment, a very stable mineral, pyromorphite Pb(5)(PO(4))(3)Cl, is formed. Several studies propose to improve this treatment method with the addition of phosphate-solubilizing bacteria (PSB). The effect of bacteria on solubilization of pyromorphite is unknown. In this study, the effect of the soil microorganisms on the stability of pyromorphite Pb(5)(PO(4))(3)Cl has been investigated in a set of batch solution experiments. The mineral was reacted with Pseudomonas putida, a common soil microorganism. Dissolution of pyromorphite was enhanced by the presence of P. putida, resulting in an elevated Pb concentration in the solution. This occurred even when the bacteria were provided with an additional source of phosphate in the solution. Pyromorphite has been shown to be a potential source of nutrient phosphorus for common soil bacteria. Thus, the use of PSB in remediation treatments of Pb contaminated sites may have adverse long-term impacts on Pb immobilization. Conscious phosphate management is suggested for long-term sustainability of the in situ Pb immobilization by pyromorphite formation

Dictionary Applied Geology English – French – German – Spanish

This dictionary was compiled by hydrogeologists from Germany, Mexico and Nicaragua. German and Spanish expressions were established by native speakers, all of them with a good knowledge of English and some French. However no native English or French speaker has reviewed the dictionary so far. Using the dictionary you will additionally recognize that some translations are still missing in one or more languages while they are already available in others. Further some special expressions you are looking for might be neglected at all. The dictionary is published by now in order to make it available to as many scientists in the field of applied geology as possible, however it is still under construction and probably will ever be. We do think about adding definitions for at least part of the words and a more convenient way to query. If you find any mistakes, missing words or if you have any additional suggestions or want to participate in our multilingual dictionary project (e.g. with a further language) please feel free to contact Prof. Dr. Broder Merkel ([email protected]. de). At the end of this four lingual introduction you will find the dictionary applied geology in four versions, all of them contain all four languages, sorted by the language listed in the file name (“English dictionary”: expressions sorted by the first column English; “Deutsches Wörterbuch”: expressions sorted by the first column German, etc.). You may download each dictionary and use the search function of the Acrobat Reader to look for the desired expression. Articles are indicated behind each word with (f) for feminine, (m) for masculine, (n) for neutral. For some words several translations exist in one language or the other. They are listed in different lines below each other. All copyrights belong to the authors. Neither the whole dictionary nor parts of it are to be published by any other user. We hope this dictionary helps you working in the multilingual field of applied geology and you will help us to further improve it. Enjoy!researc