| 1. |
- Bundschuh, J., et al.
(författare)
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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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Ingår i: Critical reviews in environmental science and technology. - : Taylor and Francis Inc.. - 1064-3389 .- 1547-6537. ; , s. 1-119
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Forskningsöversikt (refereegranskat)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. |
- Aad, G, et al.
(författare)
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- 2015
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swepub:Mat__t
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| 3. |
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| 4. |
- Ahmad, Arslan, et al.
(författare)
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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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Ingår i: One Century of the Discovery of Arsenicosis in Latin America (1914-2014). - : CRC Press. - 9781138001411 ; , s. 817-819
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Konferensbidrag (refereegranskat)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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| 5. |
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| 6. |
- Ahmad, Arslan, et al.
(författare)
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Arsenic reduction to < 1 mu g/L in Dutch drinking water
- 2020
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Ingår i: Environment International. - : Elsevier. - 0160-4120 .- 1873-6750. ; 134
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Forskningsöversikt (refereegranskat)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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| 7. |
- Ahmad, Arslan, et al.
(författare)
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Arsenite removal in groundwater treatment plants by sequential Permanganate-Ferric treatment
- 2018
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Ingår i: Journal of Water Process Engineering. - : ELSEVIER SCIENCE BV. - 2214-7144. ; 26, s. 221-229
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Tidskriftsartikel (refereegranskat)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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| 8. |
- Ahmad, Arslan, et al.
(författare)
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Characteristics of Fe and Mn bearing precipitates generated by Fe(II) and Mn(II) co-oxidation with O-2, MnO4 and HOCl in the presence of groundwater ions
- 2019
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Ingår i: Water Research. - : Elsevier. - 0043-1354 .- 1879-2448. ; 161, s. 505-516
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Tidskriftsartikel (refereegranskat)abstract
- In this work, we combined macroscopic measurements of precipitate aggregation and chemical composition (Mn/Fe solids ratio) with Fe and Mn K-edge X-ray absorption spectroscopy to investigate the solids formed by co-oxidation of Fe(II) and Mn(II) with O-2, MnO4, and HOCl in the presence of groundwater ions. In the absence of the strongly sorbing oxyanions, phosphate (P) and silicate (Si), and calcium (Ca), O-2 and HOCl produced suspensions that aggregated rapidly, whereas co-oxidation of Fe(II) and Mn(II) by MnO4 generated colloidally stable suspensions. The aggregation of all suspensions decreased in P and Si solutions, but Ca counteracted these oxyanion effects. The speciation of oxidized Fe and Mn in the absence of P and Si also depended on the oxidant, with O-2 producing Mn(III)-incorporated lepidocrocite (Mn/Fe = 0.01-0.02 mol/mol), HOCl producing Mn(III)-incorporated hydrous ferric oxide (HFO) (Mn/Fe = 0.08 mol/mol), and MnO4 producing poorly-ordered MnO2 and HFO (Mn/Fe > 0.5 mol/mol). In general, the presence of P and Si decreased the crystallinity of the Fe(III) phase and increased the Mn/Fe solids ratio, which was found by Mn K-edge XAS analysis to be due to an increase in surface-bound Mn(II). By contrast, Ca decreased the Mn/Fe solids ratio and decreased the fraction of Mn(II) associated with the solids, suggesting that Ca and Mn(II) compete for sorption sites. Based on these results, we discuss strategies to optimize the design (i.e. filter bed operation and chemical dosing) of water treatment plants that aim to remove Fe(II) and Mn(II) by co-oxidation.
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| 9. |
- Ahmad, Arslan, et al.
(författare)
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Deep-dive into iron-based co-precipitation of arsenic : A review of mechanisms derived from synchrotron techniques and implications for groundwater treatment
- 2024
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Ingår i: Water Research. - : Elsevier Ltd. - 0043-1354 .- 1879-2448. ; 249
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Forskningsöversikt (refereegranskat)abstract
- The co-precipitation of Fe(III) (oxyhydr)oxides with arsenic (As) is one of the most widespread approaches to treat As-contaminated groundwater in both low- and high-income settings. Fe-based co-precipitation of As occurs in a variety of conventional and decentralized treatment schemes, including aeration and sand filtration, ferric chloride addition and technologies based on controlled corrosion of Fe(0) (i.e., electrocoagulation). Despite its ease of deployment, Fe-based co-precipitation of As entails a complex series of chemical reactions that often occur simultaneously, including electron-transfer reactions, mineral nucleation, crystal growth, and As sorption. In recent years, the growing use of sophisticated synchrotron-based characterization techniques in water treatment research has generated new detailed and mechanistic insights into the reactions that govern As removal efficiency. The purpose of this critical review is to synthesize the current understanding of the molecular-scale reaction pathways of As co-precipitation with Fe(III), where the source of Fe(III) can be ferric chloride solutions or oxidized Fe(II) sourced from natural Fe(II) in groundwater, ferrous salts or controlled Fe(0) corrosion. We draw primarily on the mechanistic knowledge gained from spectroscopic and nano-scale investigations. We begin by describing the least complex reactions relevant in these conditions (Fe(II) oxidation, Fe(III) polymerization, As sorption in single-solute systems) and build to multi-solute systems containing common groundwater ions that can alter the pathways of As uptake during Fe(III) co-precipitation (Ca, Mg bivalent cations; P, Si oxyanions). We conclude the review by providing a perspective on critical knowledge gaps remaining in this field and new research directions that can further improve the understanding of As removal via Fe(III) co-precipitation.
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| 10. |
- Ahmad, Arslan, et al.
(författare)
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Environmental arsenic in a changing world
- 2019
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Ingår i: Groundwater for Sustainable Development. - : Elsevier. - 2352-801X. ; 8, s. 169-171
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Tidskriftsartikel (refereegranskat)
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| 11. |
- Ahmad, Arslan
(författare)
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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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Rapport (övrigt vetenskapligt/konstnärligt)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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| 12. |
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| 13. |
- Ahmad, Arslan, et al.
(författare)
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Impact of phosphate, silicate and natural organic matter on the size of Fe(III) precipitates and arsenate co-precipitation efficiency in calcium containing water
- 2020
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Ingår i: Separation and Purification Technology. - : ELSEVIER. - 1383-5866 .- 1873-3794. ; 235
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Tidskriftsartikel (refereegranskat)abstract
- Removal of arsenic (As) from water by co-precipitation with Fe(III) (oxyhydr)oxides is a widely used technique in water treatment. Nevertheless, As removal efficiency appears to be sensitive to the composition of the water matrix. The aim of this study was to gain a deeper understanding of the independent and combined effects of silicate (Si), phosphate (P), natural organic matter (NOM) and calcium (Ca) on arsenate [As(V)] co-precipitation efficiency and the size of Fe(III) precipitates. We found that, in complex solutions, containing multiple solutes and high levels of Ca, (variations in) Si and P concentrations reduce As(V) removal to some extent, mainly due to a decreased adsorption of As(V) onto Fe(III) precipitates. On the other hand, NOM concentrations reduced As(V) removal to a much greater extent, due to possible formation of mobile Fe(III)-NOM complexes that were difficult to remove by filtration. These findings have a great significance for predicting As(V) removal as a function of seasonal and process-related water quality changes at water treatment plants.
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| 14. |
- Ahmad, Arslan, et al.
(författare)
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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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Ingår i: Separation and Purification Technology. - : ELSEVIER. - 1383-5866 .- 1873-3794. ; 241
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Tidskriftsartikel (refereegranskat)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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| 15. |
- Ahmad, Arslan, et al.
(författare)
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Mobility and redox transformation of arsenic during treatment of artificially recharged groundwater for drinking water production
- 2020
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Ingår i: Water Research. - : Elsevier. - 0043-1354 .- 1879-2448. ; 178
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Tidskriftsartikel (refereegranskat)abstract
- In this study we investigate opportunities for reducing arsenic (As) to low levels, below 1 mu g/L in produced drinking water from artificially infiltrated groundwater. We observe that rapid sand filtration is the most important treatment step for the oxidation and removal of As at water treatment plants which use artificially recharged groundwater as source. Removal of As is mainly due to As co-precipitation with Fe(III)(oxyhydr)oxides, which shows higher efficiency in rapid sand filter beds compared to aeration and supernatant storage. This is due to an accelerated oxidation of As(III) to As(V) in the filter bed which may be caused by the manganese oxides and/or As(III) oxidizing bacteria, as both are found in the coating of rapid sand filter media grains by chemical analysis and taxonomic profiling of the bacterial communities. Arsenic removal does not take place in treatment steps such as granular activated carbon filtration, ultrafiltration or slow sand filtration, due to a lack of hydrolyzing iron in their influent and a lack of adsorption affinity between As and the filtration surfaces. Further, we found that As reduction to below 1 mu g/L can be effectively achieved at water treatment plants either by treating the influent of rapid sand filters by dosing potassium permanganate in combination with ferric chloride or by treating the effluent of rapid sand filters with ferric chloride dosing only. Finally, we observe that reducing the pH is an effective measure for increasing As co-precipitation with Fe(III)(oxyhydr)oxides, but only when the oxidized arsenic, As(V), is the predominant species in water.
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| 16. |
- Ahmad, Muhammad Arslan, et al.
(författare)
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Estimating the Permeability of Naturally Structured Soil From Percolation Theory and Pore Space Characteristics Imaged by X-Ray
- 2018
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Ingår i: Water Resources Research. - 0043-1397 .- 1944-7973. ; 54, s. 9255-9263
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Tidskriftsartikel (refereegranskat)abstract
- The saturated hydraulic conductivity of soil, K-s, is a critical parameter in hydrological models that remains notoriously difficult to predict. In this study, we test the capability of a model based on percolation theory and critical path analysis to estimate K-s measured on 95 undisturbed soil cores collected from contrasting soil types. One parameter (the pore geometry factor) was derived by model fitting, while the remaining two parameters (the critical pore diameter, d(c), and the effective porosity) were derived from X-ray computed tomography measurements. The model gave a highly significant fit to the K-s measurements (p<0.0001) although only 47% of the variation was explained and the fitted pore geometry factor was approximately 1 to 2 orders of magnitude larger than various theoretical values obtained for idealized porous media and pore network models. Apart from assumptions in the model that might not hold in reality, this could also be attributed to experimental error induced by, for example, air entrapment and changes in the soil pore structure occurring during sample presaturation and the measurement of K-s. Variation in the critical pore diameter, d(c), was the dominant source of variation in K-s, which suggests that d(c) is a suitable length scale for predicting soil permeability. Thus, from the point of view of pedotransfer functions, it could be worthwhile to direct future research toward exploring the correlations of d(c) with basic soil properties and site attributes.
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| 17. |
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Arsenic Research and Global Sustainability: Proceedings of the Sixth International Congress on Arsenic in the Environment (As2016), June 19-23, 2016, Stockholm, Sweden
- 2016
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Proceedings (redaktörskap) (refereegranskat)abstract
- The Congress "Arsenic in the Environment" offers an international, multi- and interdisciplinary discussion platform for research and innovation aimed towards a holistic solution to the problem posed by the environmental toxin arsenic, with considerable societal impact. The congress has focused on cutting edge and breakthrough research in physical, chemical, toxicological, medical, agricultural and other specific issues on arsenic across a broader environmental realm. The Congress "Arsenic in the Environment" was first organized in Mexico City (As2006) followed by As2008 in Valencia, Spain, As2010 in Tainan, Taiwan, As2012 in Cairns, Australia and As2014 in Buenos Aires, Argentina. The 6th International Congress As2016 was held June 19-23, 2016 in Stockholm, Sweden and was entitled Arsenic Research and Global Sustainability.
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| 18. |
- Arslan, Muhammad, et al.
(författare)
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Impact of Varying Load Conditions and Cooling Energy Comparison of a Double-Inlet Pulse Tube Refrigerator
- 2020
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Ingår i: Processes. - : MDPI. - 2227-9717. ; 8:3
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Tidskriftsartikel (refereegranskat)abstract
- Modeling and optimization of a double-inlet pulse tube refrigerator (DIPTR) is very difficult due to its geometry and nature. The objective of this paper was to optimize-DIPTR through experiments with the cold heat exchanger (CHX) along the comparison of cooling load with experimental data using different boundary conditions. To predict its performance, a detailed two-dimensional DIPTR model was developed. A double-drop pulse pipe cooler was used for solving continuity, dynamic and power calculations. External conditions for applicable boundaries include sinusoidal pressure from an end of the tube from a user-defined function and constant temperature or limitations of thermal flux within the outer walls of exchanger walls under colder conditions. The results of the system's cooling behavior were reported, along with the connection between the mass flow rates, heat distribution along pulse tube and cold-end pressure, the cooler load's wall temp profile and cooler loads with varied boundary conditions i.e. opening of 20% double-inlet and 40-60% orifice valves, respectively. Different loading conditions of 1 and 5W were applied on the CHX. At 150 K temperature of the cold-end heat exchanger, a maximum load of 3.7 W was achieved. The results also reveal a strong correlation between computational fluid dynamics modeling results and experimental results of the DIPTR.
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| 19. |
- Aullón Alcaine, Anna, et al.
(författare)
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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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Ingår i: Science of the Total Environment. - : Elsevier. - 0048-9697 .- 1879-1026. ; 715
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Tidskriftsartikel (refereegranskat)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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| 20. |
- Bhattacharya, Prosun, 1962-, et al.
(författare)
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Editors’ foreword
- 2016
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Ingår i: Arsenic Research and Global Sustainability. - London : CRC Press. - 9781315629438 ; , s. xlv-xlvi, s. xlvii-xlviii
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Konferensbidrag (refereegranskat)
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| 21. |
- Bhattacharya, Prosun, 1962-, et al.
(författare)
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Prevalence of SARS-CoV-2 in Communities Through Wastewater Surveillance—a Potential Approach for Estimation of Disease Burden
- 2021
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Ingår i: Current Pollution Reports. - : Springer Nature. - 2198-6592. ; 7:2, s. 160-166
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Tidskriftsartikel (refereegranskat)abstract
- The episodic outbreak of COVID-19 due to SARS-CoV-2 is severely affecting the economy, and the global count of infected patients is increasing. The actual number of patients had been underestimated due to limited facilities for testing as well as asymptomatic nature of the expression of COVID-19 on individual basis. Tragically, for emerging economies with high population density, the situation has been more complex due to insufficient testing facilities for diagnosis of the disease. However, the recent reports about persistent shedding of viral RNA of SARS-CoV-2 in the human feces have created a possibility to track the prevalence and trends of the disease in communities, known as wastewater-based epidemiology (WBE). In this article, we highlight the current limitations and future prospects for WBE to manage pandemics.
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| 22. |
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| 23. |
- Chwialkowska, Agnieszka, et al.
(författare)
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Co-creating value and well-being experiences in physiotherapy services
- 2022
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Ingår i: Journal of Services Marketing. - : Emerald Group Publishing Limited. - 0887-6045. ; 37:1, s. 12-24
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: The purpose of this paper is to study the US-based (American) physiotherapy customers’ goals to engage in value cocreation activities during their well-being experience. Design/methodology/approach: The authors perform Smart PLS-SEM analysis of the primary data of physiotherapy service customers in the USA. Findings: The findings show that the US well-being customer engages in physiotherapy for individualizing, empowering, development, concerted and ethical motives but not for relating motives. These findings are contrasted with previous research to show that the service-dominant logic is not sufficient to account for the contextual complexity of the well-being experience and to explain the identified differences across culturally different customer segments. Research limitations/implications: By integrating insights from health-care and cross-cultural literature, the authors highlight the importance of relationship dynamics, culture and institutional context in well-being sector and develop a more comprehensive understanding of the cocreation behaviors in this industry. This helps advance the value cocreation research in well-being sector and promote the well-being experiences such as physiotherapy. Originality/value: The authors draw from a variety of disciplinary perspectives and challenge the service-dominant (S-D) logic as insufficient in explaining the value cocreation between the customer and expert in the well-being sector. The authors adapt physician–patient relationship model from health-care literature and cultural values of power distance from cross-cultural literature to complement the S-D logic to account for the complexity and nuanced context of the well-being cocreation experience.
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| 24. |
- Del Olmo, Gonzalo, et al.
(författare)
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Influence of phosphate dosing on biofilms development on lead in chlorinated drinking water bioreactors
- 2020
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Ingår i: npj Biofilms and Microbiomes. - : Springer Nature. - 2055-5008. ; 6:1
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Tidskriftsartikel (refereegranskat)abstract
- Phosphate dosing is used by water utilities to prevent plumbosolvency in water supply networks. However, there is a lack of knowledge regarding biofilm formation on lead and plastic materials when phosphate concentrations are modified in drinking water systems. In this study, biofilms were grown over lead coupons and PVC tubes in bioreactors supplied with local drinking water treated to provide different phosphate doses (below 1, 1 and 2 mg/L) over a period of 28 days. A range of commercial iron pellets (GEH104 and WARP) were tested aiming to maintain phosphate levels below the average 1 mg/L found in drinking water. Changes in biofilm community structure in response to three different phosphate treatments were characterised by Illumina sequencing of the 16S rRNA gene for bacteria and the ITS2 gene for fungi. Scanning electron microscopy was used to visualise physical differences in biofilm development in two types of materials, lead and PVC. The experimental results from the kinetics of phosphate absorption showed that the GEH104 pellets were the best option to, in the long term, reduce phosphate levels while preventing undesirable turbidity increases in drinking water. Phosphate-enrichment promoted a reduction of bacterial diversity but increased that of fungi in biofilms. Overall, higher phosphate levels selected for microorganisms with enhanced capabilities related to phosphorus metabolism and heavy metal resistance. This research brings new insights regarding the influence of different phosphate concentrations on mixed-species biofilms formation and drinking water quality, which are relevant to inform best management practices in drinking water treatment.
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| 25. |
- del Pozo, David Fernandes, et al.
(författare)
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A novel CFD model to predict effluent solids concentration and pressure drop in deep bed granular filters for water treatment
- 2022
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Ingår i: Separation and Purification Technology. - : Elsevier BV. - 1383-5866 .- 1873-3794. ; 295
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Tidskriftsartikel (refereegranskat)abstract
- Rapid sand filtration is a widely used technology to remove suspended solids in drinking water and wastewater treatment plants. One of the challenges of the rapid sand filtration is to reliably predict the removal efficiency of suspended solids and pressure drop as a function of filtration time. In this study we put forward a novel CFD model to simultaneously predict the solids concentration in the effluent and hydraulic resistence build-up in rapid sand filters. The CFD model is assessed against lab scale filtration data at different filter media grain sizes and filtration velocities. Our results show an overall satisfactory agreement with the observations. Finally, we highlight the complexity and need for further work in developing general CFD models for rapid sand filtration.
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| 26. |
- Ghumman, Iss, et al.
(författare)
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Computational Fluid Mechanics Model for Numerical Investigation of Frictional Tribo-pair during Mixed Lubrication
- 2022
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Ingår i: Proceedings of 2022 19th International Bhurban Conference on Applied Sciences and Technology, IBCAST 2022. - : Institute of Electrical and Electronics Engineers Inc.. - 9781665460514 ; , s. 815-820
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Konferensbidrag (refereegranskat)abstract
- All the machines are constructed through mechanical links and pairs. One of the crucial pairs is the sliding pair; due to their nature and general use, they are often subjected to a higher degree of dynamics and external forces leading to high frictional force. To reduce wear from friction formerly thick film of commercial oil is used. However, viscosity-based higher thickness yields higher energy losses, and nano-lubricants are popular in reducing friction while keeping film thickness and improving wear resistance. This paper develops a numerical model for sliding pairs that predicts the load carried by components under different lubrication regimes. The aim is to simulate hydrodynamic and mixed lubrication regimes for different loading conditions. A detailed multiphysics model of tribo-pair was modeled, including lubricant rheology, surface topology, oil film squeeze, and film temperature through the moving mesh. The fluid domain has been meshed with Arbitrary Lagrangian and Eulerian techniques. Energy loss due to viscous friction and boundary friction were determined by solving Naiver- Stokes equations in the moving mesh deformable geometry domain. The numerical model was compared with the available literature, and the results are presented. This numerical simulation remained valid and provides the fundamental understanding of oil film thickness and load-carrying capacity of sliding tribo-pair in the presence of nano-lubricants. The developed model is a useful methodology for studying lubricant oil enriched with nanoparticles.
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| 27. |
- Hussain, Muhammad Mahroz, et al.
(författare)
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Arsenic biogeochemical cycling in paddy soil-rice system : Interaction with various factors, amendments and mineral nutrients
- 2021
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Ingår i: Science of the Total Environment. - : Elsevier BV. - 0048-9697 .- 1879-1026. ; 773
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Tidskriftsartikel (refereegranskat)abstract
- Arsenic (As) contamination is a well-recognized environmental and health issue, threatening over 200 million people worldwide with the prime cases in South and Southeast Asian and Latin American countries. Rice is mostly cultivated under flooded paddy soil conditions, where As speciation and accumulation by rice plants is controlled by various geo-environmental (biotic and abiotic) factors. In contrast to other food crops, As uptake in rice has been found to be substantially higher due to the prevalence of highly mobile and toxic As species, arsenile (As(Ill)), under paddy soil conditions. In this review, we discussed the biogeochemical cycling of As in paddy soil-rice system, described the influence of critical factors such as pH, iron oxides, organic matter, microbial species, and pathways affecting As transformation and accumulation by rice. Moreover, we elucidated As interaction with organic and inorganic amendments and mineral nutrients. The review also elaborates on As (im) mobilization processes and As uptake by rice under the influence of different mineral nutrients and amendments in paddy soil conditions, as well as their role in mitigating As transfer to rice grain. This review article provides critical information on As contamination in paddy soil-rice system, which is important to develop suitable strategies and mitigation programs for limiting As exposure via rice crop, and meet the UN's key Sustainable Development Goals (SDGs: 2 (zero hunger), 3 (good health and well-being), 12 (responsible consumption and production), and 13 (climate action)).
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| 28. |
- Hussain, Nazim, et al.
(författare)
-
Firm absorptive capacity : multidimensionality, drivers and contextual conditions
- 2022
-
Ingår i: Journal of Knowledge Management. - : Emerald Group Publishing Limited. - 1367-3270 .- 1758-7484. ; 26:10, s. 2718-2742
-
Tidskriftsartikel (refereegranskat)abstract
- Purpose: This paper aims to enrich absorptive capacity literature by specifically highlighting and adding environmental conditions and internationalisation process to the original conceptualisation.Design/methodology/approach: The authors undertake a conceptual analysis and present an enhanced framework of absorptive capacity by integrating multiple literature streams. The authors have analysed the most relevant literature to provide underlying justifications for the proposed conceptual model. Findings: Absorptive capacity ensures the long-term survival and success of a business. To develop absorptive capacity successfully, firms should focus on its various dimensions and existing intangible assets and external environment. The multidimensionality and richness of absorptive capacity is an under-explored area in the existing literature. The authors revisit the conceptualisation of absorptive capacity and add environmental conditions and the internationalisation process to the original conceptualisation. Absorptive capacity does not lead to a competitive advantage independent of its environment. To successfully develop it, firms have to adopt a holistic approach by considering the multi-dimensions, drivers and contextual conditions of absorptive capacity. Originality/value: This study contributes by conceptualising absorptive capacity as a dynamic capability. It is one of the first studies to specifically propose a framework that combines antecedents (prior knowledge, combinative capabilities and IT capabilities), moderators (environmental conditions, namely, market and technological turbulence, competitiveness and the internationalisation process) and consequences (competitive advantage). The study offers a unique conceptualisation with implications for researchers and managers. As a result, managers will have a well-defined blueprint to create value by using firm capabilities.
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| 29. |
- Ijumulana, J., et al.
(författare)
-
Spatial modeling of the occurrences of geogenic fluoride in groundwater systems and implications for the provision of safe drinking water in Tanzania
-
Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Inadequate data and spatial dependence in the observations during geochemical studies are among the disturbing conditions when estimating environmental factors contributing to the local variability in the pollutants of interest. Usually, spatial dependence occurs due to the researcher’s imperfection on the natural scale of occurrence which affects the sampling strategy. As a consequence, observations on the study variable are significantly correlated in space. In this study, the machine learning approach was developed and used to study the environmental factors controlling the local variability in fluoride concentration in drinking water sources of northern Tanzania within the East African Rift Valley. The approach constituted use of the geographical information systems (GIS) technology, exploratory spatial data analysis methods, and spatial modeling at a local level. The environmental variables used to study the local variation in fluoride concentration include topography, tectonic processes, water exchanges between hydrogeological layers during lateral movement, the mineralization processes (EC), and pH. The study was based on 20 local spatial regimes determined using GIS based on water sources density in the four hydrogeological environments. The non-parametric (one-way Kruskal-Wallis sum ranks test and Multiple Comparisons Dunn Test), spatial statistics (Global Moran's I statistic), ordinary least squares (OLS) regression and spatial lag models were used to quantify the effects of topography, tectonic processes, water exchange between hydrogeological environments and waterphysiochemical parameters (pH and EC) on the spatial variability of fluoride concentrations in drinking water sources at a local scale. In the order of significance, the local spatial variation in fluoride concentration is influenced by the EC, topography, tectonic processes, pH and water exchange between hydrogeological layers during water movement. The results presented in this paper are crucial for safe water access planning in the naturally contaminated aquifers.
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| 30. |
- Ijumulana, Julian, et al.
(författare)
-
Spatial modeling of the occurrences of geogenic fluoride in groundwater systems in Tanzania : Implications for the provision of safe drinking water
- 2024
-
Ingår i: Groundwater for Sustainable Development. - : Elsevier BV. - 2352-801X. ; 26
-
Tidskriftsartikel (refereegranskat)abstract
- Inadequate data and spatial dependence in the observations during geochemical studies are among the disturbing conditions when estimating environmental factors contributing to the local variability in the pollutants of interest. Usually, spatial dependence occurs due to the researcher 's imperfection on the natural scale of occurrence which affects the sampling strategy. As a consequence, observations on the study variable are significantly correlated in space. In this study, the machine learning approach was developed and used to study the environmental factors controlling the local variability in fluoride concentrations in drinking water sources of northern Tanzania within the East African Rift Valley. The approach constituted the use of geographical information systems (GIS) technology, exploratory spatial data analysis (ESDA) methods, and spatial regression modeling at a local level. The environmental variables used to study the local variation in fluoride concentration include topography, tectonic processes, water exchanges between hydrogeological layers during lateral movement, mineralization processes (EC), and water pH. The study was based on 20 local spatial regimes determined using GIS based on water sources density in the four hydrogeological environments. Specifically, the nonparametric (one-way Kruskal-Wallis sum ranks test and Multiple Comparisons Dunn Test), spatial statistics (Global Moran 's I statistic), ordinary least squares (OLS) regression, and spatial lag models were used to quantify the effects of topography, tectonic processes, water exchange between hydrogeological environments and water physiochemical parameters (pH and EC) on the spatial variability of fluoride concentrations in drinking water sources at a local scale. In order of significance, the local spatial variation in fluoride concentration is influenced by the EC, topography, tectonic processes, pH, and water exchange between hydrogeological layers during water movement. The results presented in this paper are crucial for safe water access planning in naturally contaminated aquifer systems.
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| 31. |
- Ijumulana, Julian, et al.
(författare)
-
Spatial uncertainties in fluoride levels and health risks in endemic fluorotic regions of northern Tanzania
- 2021
-
Ingår i: Groundwater for Sustainable Development. - : Elsevier BV. - 2352-801X. ; 14
-
Tidskriftsartikel (refereegranskat)abstract
- Spatial uncertainty caused by large-scale variation in fluoride (F-) occurrence remains a setback for water supply authorities in the F- belts of the world. It is estimated that approximately 80 million people in the East African Rift Valley (EARV) regions and volcanic areas exhibit a wide variety of fluorosis symptoms due to drinking water with F- concentrations higher than 1.5 mg/L (WHO guideline limit). In this study, we combined geostatistical techniques, spatial statistical methods, and geographical information systems (GIS) to (i) map the probable places with F- < 0.5 mg/L and F- > 1.5, 4.0 and 10.0 mg/L using probability kriging (PK) method, (ii) estimate the probable total population at high or low F- risk levels using univariate local Moran's I statistic, and (iii) map the spatial distribution of population at high and low F- risk levels in Manyara, Arusha and Kilimanjaro regions using GIS. It was predicted that places along the major and minor EARV mountain ranges and around the flanks of major stratovolcanoes were dominated by groundwater sources with extremely low F-(<<0.5 mg/L). In contrast, places within EARV graben were dominated by groundwater sources with F- > 1.5 mg/L. About 1 million people (similar to 20% of the total population) living around Mt. Kilimanjaro in Rombo, Moshi, and Mwanga districts are at high dental caries risk. Furthermore, it was estimated that about 2 million people (similar to 41% of the total population) in Siha, Hai, Arusha City, Hanang', Arusha, Simanjiro, and Meru districts are at high risk of dental, skeletal, and crippling fluorosis. Fluorosis, especially dental and crippling fluorosis, is an increasing disease burden at the community level due to prolonged consumption of F- contaminated water within EARV graben. The major findings of the present study are very crucial for authority to minimize the uncertainty caused by high spatial variability in geogenic F- occurrence.
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| 32. |
- Ijumulana, Julian, et al.
(författare)
-
Spatial variability of the sources and distribution of fluoride in groundwater of the Sanya alluvial plain aquifers in northern Tanzania
- 2022
-
Ingår i: Science of the Total Environment. - : Elsevier BV. - 0048-9697 .- 1879-1026. ; 810
-
Tidskriftsartikel (refereegranskat)abstract
- Groundwater contamination from geogenic sources paces challenges to many countries, especially in the developing world. In Tanzania, the elevated fluoride (F-) concentration and related chronic fluorosis associated with drinking F- rich water arc common in the Fast African Rift Valley regions. In these regions, F- concentration is space dependence which poses much uncertainty when targeting safe source for drinking water. To account for the spatial effects, integrated exploratory spatial data analysis, regression analysis, and geographical information systems tools were used to associate the distribution of F- in groundwater with spatial variability in terrain slopes, volcanic deposits, recharge water/vadose materials contact time, groundwater resource development for irrigated agriculture in the Sanya alluvial plain (SAP) of northern Tanzania. The F- concentration increased with distance from steep slopes where the high scale of variation was recorded in the gentle sloping and flat grounds within the SAP. The areas covered with debris avalanche deposits in the gentle sloping and flat grounds correlated with the high spatial variability in F- concentration. Furthermore, the high spatial variability in F- correlated positively with depth to groundwater in the Sanya flood plain. In contrast, a negative correlation between F- and borehole depth was observed. The current irrigation practices in the Sanya alluvial plain contribute to the high spatial variability in F- concentration, particularly within the perched shallow aquifers in the volcanic river valleys. The findings of this study arc important to the overall chain of safe water supply process in historically fluorotic regions. They provide new insights into the well-known F- contamination through the use of modern geospatial methods and technologies. In Tanzania's context, the findings can improve the current process of drilling permits issuance by the authority and guide the local borehole drillers to be precise in siting safe source for drinking water.
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| 33. |
- Irunde, Regina, et al.
(författare)
-
Arsenic in Africa : Potential sources, spatial variability, and the state of the art for arsenic removal using locally available materials
- 2022
-
Ingår i: GROUNDWATER FOR SUSTAINABLE DEVELOPMENT. - : Elsevier BV. - 2352-801X. ; 18, s. 100746-
-
Tidskriftsartikel (refereegranskat)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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| 34. |
- Irunde, Regina, et al.
(författare)
-
The natural magnesite efficacy on arsenic extraction from water and alkaline influence on metal release in water
- 2023
-
Ingår i: Applied Geochemistry. - : Elsevier BV. - 0883-2927 .- 1872-9134. ; 155, s. 105705-105705
-
Tidskriftsartikel (refereegranskat)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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| 35. |
- Kimambo, Vivian, et al.
(författare)
-
Fluoride occurrence in groundwater systems at global scale and status of defluoridation – State of the art
- 2019
-
Ingår i: Groundwater for Sustainable Development. - : Elsevier. - 2352-801X. ; 9
-
Forskningsöversikt (refereegranskat)abstract
- Occurrence of elevated concentrations of fluoride in the drinking water supply in many regions of the world has caused widespread dental and skeletal fluorosis. In this paper the studies available on the routes of fluoride exposure, regions with excess fluoride in water sources and various defluoridation techniques has been reviewed. It is evident from the literature survey that no single technique fits for diverse technical and socioeconomic situations and there is a pressing need to develop suitable defluoridation techniques for household and community level water supply system in order to prevent fluorosis.
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| 36. |
- Kimambo, Vivian, et al.
(författare)
-
Optimization of fluoride removal using calcined bauxite : Adsorption isotherms and kinetics
- 2023
-
Ingår i: GROUNDWATER FOR SUSTAINABLE DEVELOPMENT. - : Elsevier BV. - 2352-801X. ; 21, s. 100922-
-
Tidskriftsartikel (refereegranskat)abstract
- Geogenic contamination of groundwater due to elevated fluoride (F-) concentrations is a significant issue worldwide (including in Tanzania). The present study focussed to assess the adsorption capacity of thermally treated (calcined) bauxite to remove the F- from contaminated water. Characterization of bauxite by X-ray fluorescence spectroscopy (XRF) revealed Al2O3, Fe2O3, and SiO2 as the major oxides in both raw and calcined bauxite. The major mineral phase in the raw bauxite was gibbsite, which disappeared after calcination. The optimum calcination temperature, dosage and contact time for F- removal by calcined bauxite were 400 degrees C, 40 g/L and 8 min, respectively. The experimental data revealed Freundlich isotherm as the best model to fit the F -adsorption process with kF and 1/n being 0.1537 mg/g and 0.8607, respectively. The pseudo-second-order ki-netic and intra-particle diffusion models explained well the F- adsorption process with the rate constants of 115.43 g/mg min and 0.0025 mg/g min0.5, respectively. The values of Delta G, Delta H and Delta S indicate the F- adsorption on bauxite surface indicated that the adsorption process was spontaneous, endothermic and structural changes occurred during the adsorption process. The F- adsorption under optimum conditions lowered the pH and F -concentration to WHO and Tanzania Bureau of Standards (TBS) standards.
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| 37. |
- Ligate, Fanuel Josephat, et al.
(författare)
-
Geogenic contaminants and groundwater quality around Lake Victoria goldfields in northwestern Tanzania
- 2022
-
Ingår i: Chemosphere. - : Elsevier BV. - 0045-6535 .- 1879-1298. ; 307, s. 135732-
-
Tidskriftsartikel (refereegranskat)abstract
- Geogenic contamination of groundwater is frequently associated with gold mining activities and related to drinking water quality problems worldwide. In Tanzania, elevated levels of trace elements (TEs) have been reported in drinking water sources within the Lake Victoria Basin, posing a serious health risk to communities. The present study aims to assess the groundwater quality with a focus on the concentration levels of geogenic contaminants in groundwater around the Lake Victoria goldfields in Geita and Mara districts. The water samples were collected from community drinking water sources and were analysed for physiochemical parameters (pH, EC, Eh), major ions, and trace elements. The analysed major ions included Na+, K+, Ca2+, Mg2+, SO42-, HCO3- and Cl- whereas the trace elements were As, Al, Li, Ba, B, Ti, V, U, Zr, Sr, Si, Mn Mo, Fe, Ni, Zn, Cr, Pb, Cd, and V. The present study revealed that the concentration levels of the major ions were mostly within the World Health Organization (WHO) drinking water standards in the following order of their relative abundance; for cations, Ca2+-Na+ >Mg2+ >K+ and for anions was HCO3- > SO42- > NO3-, Cl- > PO43-. Statistical and geochemical modelling software such as 31 Studio', IBM SPSS, geochemical workbench, visual MINTEQ were used to understand the groundwater chemistry and evaluate its suitability for drinking purpose. The concentration of As in groundwater sources varies between below detection limit (bdl) and 300 mu g/L, with highest levels in streams followed by shallow wells and boreholes. In approximately 48% of the analysed samples, As concentration exceeded the WHO drinking water guideline and Tanzania Bureau of Standards (TBS) guideline for drinking water value of 10 mu g/L. The concentration of the analyzed TEs and mean values of physicochemical parameters were below the guideline limits based on WHO and TBS standards. The Canadian Council of Ministries of the Environment Water Quality Index (CCME WQI) shows that the overall water quality is acceptable with minimum threats of deviation from natural conditions. We recommend further geochemical exploration and the periodic risk assessment of groundwater in mining areas where high levels of As were recorded.
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| 38. |
- Ligate, Fanuel Josephat, et al.
(författare)
-
Groundwater resources in the East African Rift Valley: Understanding the geogenic contamination and water quality challenges in Tanzania
- 2021
-
Ingår i: Scientific African. - : Elsevier BV. - 2468-2276. ; 13
-
Tidskriftsartikel (refereegranskat)abstract
- Over the years, groundwater has been used as a means of adaptation to the seasonal and perennial scarcity of surface water. Groundwater provides water for households, livestock, and irrigation in semi-arid areas of Tanzania. It is acknowledged that groundwater is sus-ceptible to chemical and other mineral contamination which not only poses a threat to the health of human beings and livestock but also agriculture. However, the potential of groundwater in terms of its viability and quality has not received adequate scrutiny from scholars. This paper provides a review of water quality and highlights the geogenic con-tamination of groundwater resources in Tanzania. The literature reviewed focused on the water resource sector in the major drainage basins of Tanzania, the information about drinking water quality with respect to geogenic contamination were sought. This paper has established that fluoride is the main and well-known groundwater contaminant. This is attributed to the existence of fluoride-rich minerals such as fluorite (CaF2), fluorapatite (Ca-5(PO4)(3)F), cryolite (Na3AlF6), sellaite (MgF2), villiaumite (NaF), and topaz ((Al-2(SiO4)F-2), bastnaesite ((Ca, La, Nd)CO3F), and their ash deposits peeling from the granite and alka -line volcanic rocks, dominant in the region. The presence of fluoride in water sources in northern Tanzannia, part of the EARV contributes to the serious health effects on humans such as dental, skeletal, and crippling fluorosis. In addition, some literature indicated ar-senic as a serious drinking water geogenic pollutant in the north-west parts of Tanzania. They pointed out that oxidation of arsenopyrite minerals is responsible for the dissolution and release of arsenic into groundwater. From this review we conclude that information on geochemistry/hydro-geochemistry of fluoride and arsenic in the aquifers is far inadequate and recommends that more research and development (R&D) effort s from scholars, researchers, and government institutions should be invested for further investigations and solutions. The focus should be creating awareness about the danger of using arsenic and fluoride contaminated water and development of affordable and environmental friendly water purification technologies.
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| 39. |
- Litter, Marta I., et al.
(författare)
-
Arsenic in Argentina : Technologies for arsenic removal from groundwater sources, investment costs and waste management practices
- 2019
-
Ingår i: Science of the Total Environment. - : ELSEVIER. - 0048-9697 .- 1879-1026. ; 690, s. 778-789
-
Tidskriftsartikel (refereegranskat)abstract
- An overview about the presence of arsenic (As) in groundwaters of Argentina, made by a transdisciplinary group of experts is presented. In this second part, the conventional and emerging technologies for As removal, management of wastes, and the initial investment costs of the proposed technologies, with emphasis on developments of local groups are described. Successful examples of real application of conventional and emerging technologies for As removal in waters for human consumption, for medium, small and rural and periurban communities are reported. In the country, the two most applied technologies for arsenic removal at a real scale are reverse osmosis and coagulation-adsorption-filtration processes using iron or aluminum salts or polyelectrolytes as coagulants. A decision tree to evaluate the possible technologies to be applied, based on the population size, the quality of the water and its intended use, is presented, including preliminary and indicative investment costs. Finally, a section discussing the treatment and final disposal of the liquid, semiliquid and solid wastes, generated by the application of the most used technologies, is included. Conclusions and recommendations, especially for isolated rural and periurban regions, have been added.
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| 40. |
- Litter, Marta Irene, et al.
(författare)
-
Industrial applications of nanoparticles : A prospective overview
- 2023
-
Bok (övrigt vetenskapligt/konstnärligt)abstract
- Nanotechnology is one of the most rapidly developing areas of science, with great potential to solve the developmental challenges in a wide range of industries such as aerospace, agriculture, bioengineering, cosmetics, chemicals, electronics, energy, renewables, surface coatings, textiles, medicine, materials manufacturing, military equipment, etc. To compile this book, distinguished scientists, engineers, and industrial professionals from different parts of the world have been invited. An array of 17 high-quality science-based chapters covering recent advancements, challenges, and future trends in industrial applications of nanotechnology is presented. The book is aimed at industrial professionals and graduate-level students and researchers.
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| 41. |
- Litter, Marta Irene, et al.
(författare)
-
Preface
- 2023
-
Ingår i: Industrial Applications of Nanoparticles. - : Taylor and Francis.
-
Bokkapitel (övrigt vetenskapligt/konstnärligt)
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| 42. |
- Litter, Marta I., et al.
(författare)
-
The world of nanotechnology
- 2023
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Ingår i: Industrial Applications of Nanoparticles. - : Taylor and Francis. ; , s. 1-15
-
Bokkapitel (övrigt vetenskapligt/konstnärligt)
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| 43. |
- Maity, J. P., et al.
(författare)
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Advanced application of nano-technological and biological processes as well as mitigation options for arsenic removal
- 2021
-
Ingår i: Journal of Hazardous Materials. - : Elsevier BV. - 0304-3894 .- 1873-3336. ; 405
-
Tidskriftsartikel (refereegranskat)abstract
- Arsenic (As) removal is a huge challenge, since several million people are potentially exposed (>10 μg/L World Health Organization guideline limit) through As contaminated drinking water worldwide. Review attempts to address the present situation of As removal, considering key topics on nano-technological and biological process and current progress and future perspectives of possible mitigation options have been evaluated. Different physical, chemical and biological methods are available to remove As from contaminated water/soil/wastes, where removal efficiency mainly depends on absorbent type, initial adsorbate concentration, speciation and interfering species. Oxidation is an important pretreatment step in As removal, which is generally achieved by several media such as O2/O3, HClO, KMnO4 and H2O2. The Fe-based-nanomaterials (α/β/γ-FeOOH, Fe2O3/Fe3O4–γ-Fe2O3), Fe-based-composite-compounds, activated-Al2O3, HFO, Fe-Al2O3, Fe2O3-impregnated-graphene-aerogel, iron-doped-TiO2, aerogel-based- CeTiO2, and iron-oxide-coated-manganese are effective to remove As from contaminated water. Biological processes (phytoremediation/microbiological) are effective and ecofriendly for As removal from water and/or soil environment. Microorganisms remove As from water, sediments and soil by metabolism, detoxification, oxidation-reduction, bio-adsorption, bio-precipitation, and volatilization processes. Ecofriendly As mitigation options can be achieved by utilizing an alternative As-safe-aquifer, surface-water or rainwater-harvesting. Application of hybrid (biological with chemical and physical process) and Best-Available-Technologies (BAT) can be the most effective As removal strategy to remediate As contaminated environments.
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| 44. |
- Maity, Jyoti Prakash, et al.
(författare)
-
Seven 21st century challenges of arsenic-fluoride contamination and remediation
- 2021
-
Ingår i: Groundwater for Sustainable Development. - : Elsevier BV. - 2352-801X. ; 12
-
Tidskriftsartikel (refereegranskat)abstract
- Arsenic (As) and Fluoride (F) are two commonly occurring geogenic contaminants in groundwater environment, causing a range of carcinogenic and non-carcinogenic adverse health effects worldwide. Several studies have been conducted in past and many are ongoing to address As and F contamination issue of natural water. This special issue is conferring in recent times one of the emerging fields of science regarding co-occurrences of multi-contaminants within a given system and associated health risks. This special issue is divided into three sections. Section I deals with the occurrence and co-existence of As, F, and trace elements (TE) in the environment. As and F occurrence [including trace elements (TEs)] in groundwater at a global scale (example: India, Sri Lanka, Bangladesh, Ghana, and Iran, etc.) has been highlighted (Section I). The geological, and anthropogenic factors affecting As and F contamination have been observed. The state-of-art, removal techniques for As and F have been discussed. Section II and Section III incorporate all the advanced removal methods for As and F, respectively. Arsenic and F removal comprises assessing natural remediation potential (phytoremediation) including different advanced absorbents. The new findings published here, bring together a wide range of new insights on As and F behavior in the groundwater environment.
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| 45. |
- Qadri, Yazdan Ahmad, et al.
(författare)
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Preparing Wi-Fi 7 for Healthcare Internet-of-Things
- 2022
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Ingår i: Sensors. - : MDPI. - 1424-8220. ; 22:16
-
Tidskriftsartikel (refereegranskat)abstract
- The healthcare Internet of Things (H-IoT) is an interconnection of devices capable of sensing and transmitting information that conveys the status of an individual's health. The continuous monitoring of an individual's health for disease diagnosis and early detection is an important application of H-IoT. Ambient assisted living (AAL) entails monitoring a patient's health to ensure their well-being. However, ensuring a limit on transmission delays is an essential requirement of such monitoring systems. The uplink (UL) transmission during the orthogonal frequency division multiple access (OFDMA) in the wireless local area networks (WLANs) can incur a delay which may not be acceptable for delay-sensitive applications such as H-IoT due to their random nature. Therefore, we propose a UL OFDMA scheduler for the next Wireless Fidelity (Wi-Fi) standard, the IEEE 802.11be, that is compliant with the latency requirements for healthcare applications. The scheduler allocates the channel resources for UL transmission taking into consideration the traffic class or access category. The results demonstrate that the proposed scheduler can achieve the required latency for H-IoT applications. Additionally, the performance in terms of fairness and throughput is also superior to state-of-the-art schedulers.
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| 46. |
- Quino Lima, Israel, 1980-, et al.
(författare)
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Geochemical mechanisms and spatio-temporal variation of the mobility of natural arsenic in shallowgroundwater and surface water in the hydrogeologic system of Lower Katari Basin, Bolivian Altiplano.
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Arsenic (As) contamination of drinking water is a world-wide problem. The natural origin of As, its mobility and transport are of great interest in Bolivian Altiplano due to its presence in mineral deposits, brines, hot springs and volcanic rocks. In this study a geochemical spatial-temporal approach was used to understand the sources and factors that control the mobilization and fate of As in water bodies as well as sediments of Lower Katari Basin (LKB). The results reveal that high levels of As, boron (B), manganese (Mn) and high salinity are present in shallow drinking water wells, which exceed the guideline values of the Bolivian regulation (NB-512) and WHO. The seasonal variation and its impact on water quantity, in addition to the load of solids and liquids of residual origin (Pallina River) represent risk of significant negative health impact for the communities at the banks of the Katari River. The first evaluation of the hydrogeological study indicates that the groundwater flow was observed in the direction southeast - northwest (SE - NW), which are showed in the sectors with interaction between groundwater and surface water. The spatial distribution of As varies considerably due to geological characteristics of the area as well as due to the heterogeneously distributed evaporites in the sediments; however, the highest concentrations of As are found in the alluvial sediments of the northern region. Sequential extraction of sediment along with geochemical modeling (mineral saturation indices) indicates that the iron (Fe) and aluminum (Al) oxides as well as their hydroxides are most important adsorbent minerals of As in central and southern region of LKB. The hydrochemistry of water bodies in LKB is strongly influenced by the interaction with the sediment constituents and by the spatial-temporal variations. Therefore, the determination of the distribution of As among the different geochemical fractions was useful to find the relative proportions of As transported by different chemical mechanisms and their spatial-temporal variation.
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| 47. |
- Quino Lima, Israel, Doctoral student, 1980-, et al.
(författare)
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Geochemical mechanisms of natural arsenic mobility in the hydrogeologic system of Lower Katari Basin, Bolivian Altiplano
- 2021
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Ingår i: Journal of Hydrology. - : Elsevier BV. - 0022-1694 .- 1879-2707. ; 594
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Tidskriftsartikel (refereegranskat)abstract
- Arsenic (As) contamination of drinking water is a worldwide problem. The natural origin of As, its mobility, and transport are of paramount interest in Bolivian Altiplano due to its presence in mineral deposits, brines, hot springs, and volcanic rocks. In this study, a geochemical spatial-temporal approach was used to understand the sources and factors that regulate the mobilization and fate of As in water bodies as well as sediments of Lower Katari Basin (LKB). The study reveals that high levels of As (288 mu g/L), boron (B) (2473 mu g/L), manganese (Mn) (7259 mu g/L), and high salinity (23850 mu S/cm) are present in shallow drinking water wells, which exceed the guideline values of the Bolivian regulation (NB-512) and WHO. Seasonal changes (mean monthly rainfall in the dry and rainy period: 6-89 mm) and their impact on water quantity (0.9-5.1 m(3)/s), in addition to the load of solids and liquids of residual origin (Pallina River), pose health risks for the communities at the banks of the Katari River. The hydrogeological study indicates that the groundwater flows from southeast to northwest (SE-NW), which indicate interaction between groundwater and surface water in this region. The spatial distribution of As varies considerably due to geological characteristics of the area as well as due to the heterogeneously distributed evaporites in the sediments (alluvial, fluvial-lacustrine); however, the highest concentrations of As are observed in the alluvial sediments of the northern region. Sequential extraction (BCR) of sediments along with geochemical modeling (mineral saturation indices) indicates that iron (Fe) and aluminum (Al) (hydr)oxides are the most important adsorbent minerals of As in the central and southern region of LKB. The hydrochemistry of water bodies in LKB is strongly influenced by the interaction with the sediment constituents and by the spatial-temporal variations. Therefore, the determination of the distribution of As among the different geochemical fractions was useful to find the relative proportions of As transported by different chemical mechanisms (adsorption/dissolution) and their spatial-temporal variation.
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| 48. |
- Quino Lima, Israel, 1980-, et al.
(författare)
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Hydrogeochemical contrasts in the shallow aquifer systems of the Lower Katari Basin and SouthernPoopó Basin, Bolivian Altiplano.
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Water sources for human consumption in regions such as the southeast of Lake Titicaca (Lower Katari Basin: LKB) and the south of Lake Poopó (Southern Poopó Basin: SPB) have high concentrations of arsenic (As) (>10 μg/L; WHO and NB-512 guideline value). These regions belong to the Bolivian Altiplano and characterized by a semiarid climate, slow hydrological flow, with geological formations of volcanic origin, in addition to brines and other mineral deposits. This study focuses in the comparision of the geochemical processes for the occurance of As, sources and its mobilization in groundwater (GW) in LKB and SPB. Samples of GW, surface water and sediments were collected from both the basins. The study found As (LKB: 0.8 - 288 μg/L and SPB: 2.6 - 207 μg/L), boron (B) (LKB: 96 - 2473 μg/L and SPB: 507 - 4359 μg/L), manganese (Mn) (LKB: 0.6 - 7259 μg/L) and salinity (LKB: 125 - 11740 μS/cm) are higher than the WHO guideline. The results indicate serious deterioration of GW quality that is apparently not safe for human consumption. The spatial distribution of As was observed in diverse geology of both the basins and it was heterogeneously distributed within the sediments. The highest As concentrations are found in the northern region of LKB and the PACK belt in SPB (both alluvial sediments). The dissolution and exchange of bases are the processes that govern the mineralization of GW. Whereas, sequential extraction of sediment and mineral saturation indices indicate the iron (Fe) and aluminum (Al) oxides as well as hydroxides are the most predominant mineral as potential sorbent of As. Nevertheless, solids and liquid from anthropogenic origin in surface water (LKB) are causing environmental problem for communities on the banks of river.
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| 49. |
- van Genuchten, C. M., et al.
(författare)
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Heavy metal removal potential of olivine
- 2023
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Ingår i: Water Research. - : Elsevier BV. - 0043-1354 .- 1879-2448. ; 245
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Tidskriftsartikel (refereegranskat)abstract
- Industrial wastewater containing heavy metals, such as Cd and Pb, must be treated prior to discharge to meet increasingly stringent discharge guidelines and to limit the impact of toxic metals on ecosystems and human health. The application of olivine particles is a natural mineral-based solution to treat heavy metal-laden wastewaters, but little is known about the efficiency and mechanism of metal removal by this solid phase. In this work, we investigate the potential of olivine for heavy metal treatment by combining batch metal removal experiments with solid-phase characterization by synchrotron-based X-ray techniques and electron microscopy. We probed the removal behaviour of a variety of metal contaminants (Co, Ni, Cd, Zn, Cu, Pb; initial concentration = 1500 µg/L) and used Zn specifically to identify the metal removal pathway of olivine. We found that olivine in powdered (0.3 g/L) and granulated (0.5 g/L) forms was able to remove up to >90% of the initial metal, depending on the metal identity, with the efficiency increasing in order of Co ≤ Cd ≤ Ni
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| 50. |
- Yıldızel, Sadık Alper, et al.
(författare)
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Experimental Investigation and Analytical Prediction of Flexural Behaviour of Reinforced Concrete Beams with Steel Fibres Extracted from Waste Tyres
- 2023
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Ingår i: Case Studies in Construction Materials. - : Elsevier. - 2214-5095. ; 19
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Tidskriftsartikel (refereegranskat)abstract
- In recent years, studies on the use of car tyre wastes in concrete have gained momentum. Especially, the effect of recycled waste steel wires (RWSWs) from tyres to be mixed into concrete for using in newly designed reinforced concrete buildings on the performance of construction elements is a fairly new research area. In this study, the bending behaviour of 12 reinforced concrete beams was investigated having 1/3 geometric scale, 100 × 150 × 1000 mm in size, and produced with RWSWs additive in different volumetric ratios (1%, 2%, and 3%) under vertical loads. Another main parameter selected in the study was the amount of varying tension reinforcements (2ϕ12, 2ϕ10, and 2ϕ8). The load-carrying, stiffness, ductility, and energy dissipation capacities of the RWSW reinforced bending beams were compared with the primary aim of this study which was to examine and present the contribution of RWSWs on the improvement of the bending performance of the reinforced concrete beams. The results revealed that the mechanical properties of the hybrid beams with RWSWs vary depending on dosages but are comparable with those of the beams-only with the same fibre dosage. A positive effect was obtained for the hybrid beams containing 2–3% RWSWs. Besides, RWSWs were found to be highly well mobilised at larger crack widths, and the post-cracking strength of RWSW mixes was significantly higher. Considering both mechanical properties of the beams and fresh properties such as the workability, 2% of RWSWs is recommended to be utilised in the reinforced concrete beams. On the other hand, the results were compared with the predictions of the methods given in the literature and standards. Moreover, an equation was derived to better predict the capacity of the hybrid beams using RWSWs.
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