| 1. |
- Bundschuh, J., et al.
(author)
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Arsenic in Latin America : New findings on source, mobilization and mobility in human environments in 20 countries based on decadal research 2010-2020
- 2020
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In: Critical reviews in environmental science and technology. - : Taylor and Francis Inc.. - 1064-3389 .- 1547-6537. ; , s. 1-119
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Research review (peer-reviewed)abstract
- Today (year 2020), the globally recognized problem of arsenic (As) contamination of water resources and other environments at toxic levels has been reported in all of the 20 Latin American countries. The present review indicates that As is prevalent in 200 areas across these countries. Arsenic is naturally released into the environment and mobilized from geogenic sources comprising: (i) volcanic rocks and emissions, the latter being transported over thousands of kilometers from the source, (ii) metallic mineral deposits, which get exposed to human beings and livestock through drinking water or food chain, and (iii) As-rich geothermal fluids ascending from deep geothermal reservoirs contaminate freshwater sources. The challenge for mitigation is increased manifold by mining and related activities, as As from mining sites is transported by rivers over long distances and even reaches and contaminates coastal environments. The recognition of the As problem by the authorities in several countries has led to various actions for remediation, but there is a lack of long-term strategies for such interventions. Often only total As concentration is reported, while data on As sources, mobilization, speciation, mobility and pathways are lacking which is imperative for assessing quality of any water source, i.e. public and private.
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| 2. |
- Bhattacharya, Prosun, 1962-, et al.
(author)
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Editors’ foreword
- 2016
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In: Arsenic Research and Global Sustainability. - London : CRC Press. - 9781315629438 ; , s. xlv-xlvi, s. xlvii-xlviii
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Conference paper (peer-reviewed)
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| 3. |
- Irunde, Regina, et al.
(author)
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Arsenic in Africa : Potential sources, spatial variability, and the state of the art for arsenic removal using locally available materials
- 2022
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In: GROUNDWATER FOR SUSTAINABLE DEVELOPMENT. - : Elsevier BV. - 2352-801X. ; 18, s. 100746-
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Journal article (peer-reviewed)abstract
- In the past two decades, several studies on arsenic (As) occurrence in the environment, particularly in surface and groundwater systems have reported high levels of As in some African countries. Arsenic concentrations up to 10,000 mu g/L have been reported in surface water systems, caused by human activities such as mining, industrial effluents, and municipal solid waste disposals. Similarly, concentrations up to 1760 mu g/L have been reported in many groundwater systems which account for approximately 60% of drinking water demand in rural Africa. Naturally, As is mobilized in groundwater systems through weathering processes and dissolution of As bearing minerals such as sulfides (pyrite, arsenopyrite, and chalcopyrite), iron oxides, other mineralized granitic and gneissic rocks, and climate change factors triggering As release in groundwater. Recently, public health studies in some African countries such as Tanzania and Ethiopia have reported high levels of As in human tissues such as toenails as well as in urine among pregnant women exposed to As contaminated groundwater, respectively. In urine, concentrations up to 150 mu g/L were reported among pregnant women depending on As contaminated drinking water within Geita gold mining areas in the north-western part of Tanzania. However, the studies on As occurrence, and mobilization in African water systems, as well as related health effects are limited, due to the lack of awareness. The current study aims to gather information on the occurrence of As in different environmental compartments, its spatial variability, public health problems and the potential remediation options of As in water sources. The study also aims at creating awareness of As contamination in Africa and its removal using locally available materials.
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| 4. |
- Ahmad, Arslan, et al.
(author)
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Arsenic reduction to < 1 mu g/L in Dutch drinking water
- 2020
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In: Environment International. - : Elsevier. - 0160-4120 .- 1873-6750. ; 134
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Research review (peer-reviewed)abstract
- Arsenic (As) is a highly toxic element which naturally occurs in drinking water. In spite of substantial evidence on the association between many illnesses and chronic consumption of As, there is still a considerable uncertainty about the health risks due to low As concentrations in drinking water. In the Netherlands, drinking water companies aim to supply water with As concentration of < 1 mu g/L - a water quality goal which is tenfold more stringent than the current WHO guideline. This paper provides (i) an account on the assessed lung cancer risk for the Dutch population due to pertinent low-level As in drinking water and cost-comparison between health care provision and As removal from water, (ii) an overview of As occurrence and mobility in drinking water sources and water treatment systems in the Netherlands and (iii) insights into As removal methods that have been employed or under investigation to achieve As reduction to < 1 mu g/L at Dutch water treatment plants. Lowering of the average As concentration to < 1 mu g/L in the Netherlands is shown to result in an annual benefit of 7.2-14 M(sic). This study has a global significance for setting drinking water As limits and provision of safe drinking water.
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| 5. |
- Ahmad, Arslan, et al.
(author)
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Arsenite removal in groundwater treatment plants by sequential Permanganate-Ferric treatment
- 2018
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In: Journal of Water Process Engineering. - : ELSEVIER SCIENCE BV. - 2214-7144. ; 26, s. 221-229
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Journal article (peer-reviewed)abstract
- The Dutch drinking water sector is actively investigating methods to reduce arsenic (As) to < 1 mu g/L in drinking water supply. We investigated (1) the effectiveness of sequential permanganate (MnO4-)-ferric (Fe(III)) dosing during aeration-rapid sand filtration to achieve < 1 mu g/L As (2) the influence of MnO4--Fe(III) dosing on preestablished removal patterns of As(III), Fe(II), Mn(II) and NH4+ in rapid sand filters and (3) the influence of MnO4--Fe(III) dosing on the settling and molecular-scale structural properties of the filter backwash solids. We report that MnO4--Fe(III) dosing is an effective technique to improve arsenite [As(III)] removal at groundwater treatment plants. At a typical aeration-rapid sand filtration facility in the Netherlands effluent As concentrations of < 1 mu g/L were achieved with 1.2 mg/L MnO4--and 1.8 mg/L Fe(III). The optimized combination of MnO4-and Fe(III) doses did not affect the removal efficiency of Fe(II), Mn(II) and NH4+ in rapid sand filters, however, the removal patterns of Fe(II) and Mn(II) in rapid sand filter were altered, as well as the settling behaviour of backwash solids. The characterization of backwash solids by Fe K-edge X-ray absorption spectroscopy (XAS) and X-ray diffraction (XRD) showed that the changed settling velocity of backwash solids with MnO4-Fe(III) in place was not due to changes in the molecular-scale structure of Fe-precipitates that constitute the major portion of the backwash solids.
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| 6. |
- Ahmad, Arslan
(author)
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Evaluation and optimization of advanced oxidation coagulation filtration (AOCF) to produce drinking water with less than 1 μg/L of arsenic
- 2014
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Reports (other academic/artistic)abstract
- Arsenic is an extremely poisonous element. It has been reported to cause contamination of drinking water sources in many parts of the world. The current drinking water permissible limit for arsenic in the European Union is 10 μg/L. The World Health Organization has a general rule that no substance may have a higher lifetime risk of more than 1 in 100,000. However, several studies on toxicity of arsenic suggest that purely based on health effects the arsenic limit of 10 μg/L is not sufficient. The main goal of this research was to develop an efficient arsenic removal technology that could be able to produce drinking water with an arsenic concentration of less than 1 μg/L. For this purpose, an innovative three step technique, Advanced Oxidation - Coagulation - Filtration (AOCF), was investigated through bench-scale and pilot scale experiments in the Netherlands at the water treatment plant of Dorst. Firstly, prior to the investigations on AOCF, the existing arsenic removal at the water treatment plant was investigated. Secondly, through a series of bench-scale experiments, the optimum type of coagulant, its combination dose with the selected chemical oxidant and optimum process pH were determined. Eventually, the partially optimized technique from the bench-scale was implemented at the pilot scale physical model of water treatment plant Dorst where AOCF was evaluated for arsenic removal and its effect on the removal of other common undesirable groundwater constituents. The optimized AOCF technology consistently removed arsenic from groundwater to below 1 ug/L when implemented at pilot scale. The overall effluent quality also remained acceptable. The method is efficient with both types of filtration media tested in this research i.e., virgin sand and metal oxide coated sand, however virgin sand media showed slightly better arsenic removal efficiency.
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| 7. |
- Ahmad, Arslan, et al.
(author)
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Mechanisms of arsenate removal and membrane fouling in ferric based coprecipitation-low pressure membrane filtration systems
- 2020
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In: Separation and Purification Technology. - : ELSEVIER. - 1383-5866 .- 1873-3794. ; 241
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Journal article (peer-reviewed)abstract
- Ferric based coprecipitation-low pressure membrane filtration is a promising arsenic (As) removal method, however, membrane fouling mechanisms are not fully understood. In this study we investigated the effect of feed water composition and membrane pore size on arsenate [As(V)] removal and membrane fouling. We observed that As removal efficiency was independent of the membrane pore size because the size of the Fe(III) particles was larger than the pore size of the membranes, attributed to a high calcium concentration in the feed water. Arsenic coprecipitation with Fe(III) (oxyhydr)oxides rapidly reached equilibrium before membrane filtration, within 1 min. Therefore, As removal efficiency was not improved by increasing residence time before membrane filtration. The removal of As(V) was strongly dependent on feed water composition. A higher Fe(III) dose was required to reduce As(V) to sub-mu g/L levels for feed water containing higher concentration of oxyanions such as phosphate and silicate, and lower concentration of cations such as calcium. Cake-layer formation was observed to be the predominant membrane fouling mechanism.
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| 8. |
- Aullón Alcaine, Anna, et al.
(author)
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Hydrogeochemical controls on the mobility of arsenic, fluoride and other geogenic co-contaminants in the shallow aquifers of northeastern La Pampa Province in Argentina
- 2020
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In: Science of the Total Environment. - : Elsevier. - 0048-9697 .- 1879-1026. ; 715
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Journal article (peer-reviewed)abstract
- Elevated Arsenic (As) and Fluoride (F) concentrations in groundwater have been studied in the shallow aquifers of northeastern of La Pampa province, in the Chaco-Pampean plain, Argentina. The source of As and co-contaminants is mainly geogenic, from the weathering of volcanic ash and loess (rhyolitic glass) that erupted from the Andean volcanic range. In this study we have assessed the groundwater quality in two semi-arid areas of La Pampa. We have also identified the spatial distribution of As and co-contaminants in groundwater and determined the major factors controlling the mobilization of As in the shallow aquifers. The groundwater samples were circum-neutral to alkaline (7.4 to 92), oxidizing (Eh similar to 0.24 V) and characterized by high salinity (EC = 456-11,400 mu S/cm) and Na+-HCO3- water types in recharge areas. Carbonate concretions ("tosca") were abundant in the upper layers of the shallow aquifer. The concentration of total As (5.6 to 535 mu g/L) and F (0.5 to 14.2 mg/L) were heterogeneous and exceeded the recommended WHO Guidelines and the Argentine Standards for drinking water. The predominant As species were arsenate As(V) oxyanions, determined by thermodynamic calculations. Arsenic was positively correlated with bicarbonate (HCO3-), fluoride (F), boron (B) and vanadium (V), but negatively correlated with iron (Fe), aluminium (Al), and manganese (Mn), which were present in low concentrations. The highest amount of As in sediments was from the surface of the dry lake. The mechanisms for As mobilization are associated with multiple factors: geochemical reactions, hydrogeological characteristics of the local aquifer and climatic factors. Desorption of As(V) at high pH, and ion competition for adsorption sites are considered the principal mechanisms for As mobilization in the shallow aquifers. In addition, the long-term consumption of the groundwater could pose a threat for the health of the local community and low cost remediation techniques are required to improve the drinking water quality.
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| 9. |
- Irunde, Regina, et al.
(author)
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The natural magnesite efficacy on arsenic extraction from water and alkaline influence on metal release in water
- 2023
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In: Applied Geochemistry. - : Elsevier BV. - 0883-2927 .- 1872-9134. ; 155, s. 105705-105705
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Journal article (peer-reviewed)abstract
- Arsenic (As) removal studies were carried out through batch experiments to investigate the performance of the locally available calcined magnesite mineral rocks from Tanzania. Natural water from a stream source in Tanzania and the prepared synthetic water at the laboratory were used for the studies. Parameters such as initial As concentration, calcined magnesite dosage, contact time and pH were evaluated for As removal using an overhead rea×2 shaker. Arsenic concentration was reduced from 5.3 to 1.1 mg/L As(V) at 180 min when 0.5 g/L calcined magnesite was applied to a synthetic water sample, whereas the concentration of 117 μg/L As(V) and 5.2 μg/L As(III) was reduced to below 0.1 μg/L in natural water. An increase in calcined magnesite dosage resulted in increased As removal up to below 0.01 mg/L. The calcined magnesite raised the pH of the water sample from 6.8 to 10 when the applied dosage increased between 0.002 g/L and 0.05 g/L. The pH was constant at around 10 even when the amount of 0.05 g/L was added 2000 times. Despite the high pH, the amount of magnesium released in water was low. The calcination of magnesite at 500 ◦C increased surface area by 4 times as compared to the natural magnesite and X-ray diffraction showed presence of MgCO3 phase as the dominant phase at this temperature. The reaction kinetics of As removal on 0.5 g/L calcined magnesite fitted with the pseudo-second-order (R2 = 0.96). Reaction isotherm was strongly fitted with Freundlich isotherm (R2 = 0.98). Linear regression and artificial intelligence neural network showed the As removal was influenced by both contact time and pH. Arsenic can be removed from As water using calcined magnesite and will be suitable for water treatment around gold mining areas.
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| 10. |
- Ahmad, Arslan, et al.
(author)
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Advanced Oxidation-Coagulation-Filtration (AOCF) - An innovative treatment technology for targeting drinking water with <1 μg/L of arsenic
- 2014
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In: One Century of the Discovery of Arsenicosis in Latin America (1914-2014). - : CRC Press. - 9781138001411 ; , s. 817-819
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Conference paper (peer-reviewed)abstract
- Advanced Oxidation-Coagulation-Filtration (AOCF) has been investigated for producing drinking water with less than 1 μg L-1 of As through a series of bench scale and pilot scale experiments. At bench scale, the suitable coagulant, its combination dose with KMnO4 oxidant, the optimum process pH and kinetics of As removal were determined. The optimized AOCF technique was capable of consistently reducing the As concentration to below 1 μg L-1 when implemented at pilot scale and did not adversely affect the already existing removal processes of Fe, Mn and NH4 +. Dual media filter solved the filter run time reduction issue.
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