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- Abarca, R. R. M., et al.
(författare)
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Metals toxic pollutants in the environment : Anthropogenic and geological causes and remediation
- 2019
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Ingår i: Current Trends and Future Developments on (Bio-) Membranes: Membranes in Environmental Applications. - : Elsevier Inc.. ; , s. 109-124
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- Heavy metals are naturally present in nature, but if their concentration is higher than the normal accepted threshold levels, they constitute one of the pollutants that is more difficult to remove and also to rehabilitate the contaminated site by them. There are many heavy-metal pollutants-the most common among them are arsenic (As), chromium (Cr), lead (Pb), mercury (Hg), cadmium (Cd), cobalt (Co), copper (Cu), iron (Fe), magnesium (Mg), manganese (Mn), molybdenum (Mo), nickel (Ni), selenium (Se), and zinc (Zn), along with the less common ones, which produced, for example, by the nuclear process, such as uranium (U)-in different configuration; hence, many possibilities of contamination in the world exist, and they are more difficult to remove.Thus heavy-metal pollution is more and more becoming one of the principal issues of the global interest, because it is common to both industrialized countries and developing countries. These issues are getting hard to be recognized and cannot be followed the simple rules concerning safety and environmental protection, thus fall into the same errors of the already industrialized countries. At the same time, new environment-remediation techniques are developed in the last decade, especially, in these last years. Some of these technologies concern physical or chemical process or effects, such as ion exchanges, flotations, and photocatalysis, while other technologies concern the use of membrane process, especially ultrafiltration or membrane integrated process or hybrid systems, where membranes are generally submerged and used together with another process.In this chapter a review of this problem and some example of technologies for removing and remediation of the environment are reported.
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| 4. |
- Alam, M.S., et al.
(författare)
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Controls of sedimentary facies on arsenic mobilization in shallow aquifers of the Matlab North Upazila, southeastern Bangladesh
- 2013
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Groundwater extracted from shallow (<100 m bgl) Holocene alluvial aquifers, is the primary source of drinking water in Matlab North Upazila, Southeast Bangladesh. The distribution of lithofacies and its relation to hydrochemistry in such heterogeneous deposits are of fundamental importance for the analysis of groundwater quality. Aquifer sediment samples were collected from 48 locations throughout the study area. Lithofacies distribution was characterized using grain size and sediment colors. Channel fills (sandy) and over bank (silt-clay) deposits the two main lithofacies groups, were identified. These sandy deposits represent an active meandering river or channel fills sediment sequence, which are usually capped by silts and clays of an over bank sediment sequence. All the collected sediments samples were generalized and subdivided based on four distinct color variations, such as Black, White, Off-white, and Red according to Munsell color chart and water-well drillers’ perception.Mineral compositions showed variability with the sediment color and grain size. Red and off-white sediments contain fewer amounts of metastable minerals (hornblende, actinolite, kyanite and pyroxenes etc.) than that of black sediments, whereas black sediments contain higher amount of biotite. The relatively high content of biotite and other dark colored ferromagnesian minerals are responsible for the black and grayish color of these sediments. Ferruginous coating on silicates, particularly on quartz grains, gives the red and off-white coloration. Based on the available information regarding sediment colors of aquifers in which tubewell screens were placed, 44 domestic hand pumped tubewells (HTWs) were selected for water sampling. The groundwater abstracted from black sediments of shallow aquifer showed higher concentrations in DOC (median: 5.81 mg/L), dissolved NH4+ (median: 3.47 mg/L), PO43- (median: 1.36 mg/L), Fe (median: 4.87 mg/L), As (median: 252.53 μg/L) and relatively low Mn (median: 0.54 mg/L) and SO42-(median: 0.59 mg/L) concentrations, whereas groundwater abstracted from off-white and red sediments of shallow aquifer showed lower concentrations in DOC (median: 1.95 and 1.71 mg/L, respectively), dissolved NH4+ (median: 0), PO43- (median: 0.14 and 0.04 mg/L, respectively), Fe (median: 2.25 and 0.63 mg/L, respectively), As (median: 17.36 and 15.05 μg/L, respectively) and relatively high Mn+2 (median: 1.12 and 1.15 mg/L, respectively) and SO42- (median: 0.79 and 0.78 mg/L, respectively) concentrations. The water samples collected from black sediments (median Eh: 211 mV) indicated most reducing environment, followed by white (median Eh: 227 mV), whereas off-white and red sediments (median Eh: 268 and 274 mV) signified less reducing environment. The study supports that the sediment colors in shallow aquifer can be a reliable indicator of high and low-As concentrations and can be a useful tool for local drillers to target arsenic safe aquifers.
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| 7. |
- Annaduzzaman, Md, 1986-
(författare)
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Chitosan biopolymer as an adsorbent for drinking water treatment : Investigation on Arsenic and Uranium
- 2015
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In many countries over the world (including Sweden), metal toxicity in freshwater resources causes a severe drinking water quality problem and poses a threat to the environment and human health. Among the different toxic metals in the water resources of Sweden, arsenic and uranium are the biggest threats to health. These elements, over long time consumption, may even lead to cancer and/or neurological disorder. Most of the wells are installed in crystalline and sedimentary bedrock and the received water comes from water bearing fractures in the bedrock. The handling of such water is an issue and there is a need to reduce the arsenic and uranium exposure by improving processes and technologies. It is a very serious problem demanding a safe, sustainable and eco-friendly arsenic and uranium removal technology prior to drinking water supply. Different treatment systems are available, but many of them are not suitable due to their high cost, operation complexity and waste management issues. Through this study, chitosan biopolymer the second largest abundant polysaccharide on earth after cellulose, was verified as a potential adsorbent for arsenic(V) and uranium(VI) removal from water solution. Adsorbent characterizations were also conducted by XRD, FTIR, SEM, UV-visible spectrum and TGA/DTA investigations. Bench-scale batch experiments were conducted using chitosan biopolymer (DDA-85%) as an adsorbent to determine the arsenic(V) and uranium(VI) removal efficiency, by allowing four important effective parameters e.g. chitosan dosages, pH, contact time and contaminant concentration. The adsorption data at optimum conditions were fitted with Langmuir, Freundlich and Dubinin-Radushkhevic (D-R) isotherm and Lagergren pseudo-first-order and pseudo-second-order kinetic model to investigate the adsorption process. The characterization of materials assured the presence of effective amino, hydroxyl, and carboxyl groups of chitosan. Another advanntage is that the materials are bio-degradable. The results show that the arsenic(V) and uranium(VI) removal efficiency was 100% and 97.45% after 300 minutes with optimum pH of 6.0 and 7.0 respectively. The optimum adsorbent dosages and initial concentration were 60 and 80g/L and 100 and 250 µg/L respectively. The adsorption process was suitably described by Freundlich isotherm (R2 = 0.9933) and Langmuir isotherm (R2 = 0.9858) correspondingly for arsenic(V) uranium(VI) compared to other isotherms. This is an important indicator of homogeneous monolayer adsorption of metals. For both of arsenic(V) and uranium(VI), pseudo-second-order explained the adsorption kinetics better than pseudo-first-order and the second-order kinetic regression coefficient (R2) were 0.9959 and 0.9672 correspondingly. Connecting to the above mentioned results, it can be summed up that the chitosan biopolymer (DDA 85%) can be used as an inexpensive, sustainable and environment-friendly treatment option for arsenic(V) and uranium(VI) contaminated drinking water.
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| 9. |
- Annaduzzaman, Md., et al.
(författare)
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Tubewell platform color : A low-cost and rapid screening tool for arsenic and manganese in drinking water
- 2013
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Presence of high level of geogenic arsenic (As) in groundwater is one of the major and adverse drinking water quality problem all over the world, especially in Southeast Asia, where groundwater is the prominent drinking water source. Bangladesh is already considered as one of the most As affected territories, where As contamination in the groundwater is key environmental disasters. Recently besides As, presence of high level of manganese (Mn) in drinking water has also got attention due to its neurological effect on children. It becomes very essential to formulate a reliable safe drinking water management policy to reduce the health threat caused by drinking As and Mn contained groundwater. The development of a simple low cost technique for the determination of As and Mn in drinking water wells is an important step to formulate this policy. The aim of this study was to evaluate the potentiality of tubewell platform color as low-cost, quick and convenient screening tool for As and Mn in drinking water wells (n=272) in a highly arsenic affected area on Matlab, Southeastern Bangladesh.The result shows strong correlation between the development of red color stain on tubewell platform and As enrichment in the corresponding tubewell water compared to WHO drinking water guideline (10 μg/L) as well as Bangladesh drinking water standard (BDWS) (50 μg/L), with certainty values of 98.7% and 98.3% respectively. The sensitivity and efficiency of red colored platforms to screen high As water in tubewells are 98% and 97% respectively at 10 μg/L, whereas at cut-off level of 50μg/L both sensitivity and efficiency values are 98%. This study suggests that red colored platform could be potentially used for primary identification of tubewells with elevated level of As and thus could prioritise sustainable As mitigation management in developing countries. Due to lack of tubewells with black colored platform in the study area, the use of platform color concept for screening of Mn enriched water in the wells have not been tested significantly, which requires further study.Acknowledgements: This study was carried out with support from the Liuuaeus-Palme Academic Exchange Programme supported by International Programs Office (IPK) and the KTH led joint collaborative action research project on Sustainable Arsenic Mitigation- SASMIT (Sid Contribution 750000854).
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| 10. |
- Aullón Alcaine, Anna, et al.
(författare)
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Geogenic arsenic and fluoride in shallow aquifers of northeastern La Pampa, Argentina : mobility constraints
- 2013
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- High concentrations of geogenic arsenic (As) and fluoride (F-) in groundwater have been reported at elevated concentrations in different parts of the Chaco-Pampean Plain, in Argentina, where more than 2 million people may be exposed to high levels of these toxic elements through drinking water. Groundwater from the shallow aquifer is far exceeding the permissible WHO Standard limits of 10 μg/L for As and 1.5 mg/L for fluoride, as well as the Argentinean Standard limit of 50 μg/L for As. Geogenic As results due to the weathering of ash originated by volcanic eruptions from the Andean Cordillera and transported by wind and deposited along with the sediments and also as discrete layers and lenses over large geographical area containing around 90% of rhyolitic glass. Groundwater is hosted in a sandy silty interconnected system of aquifers and aquitards within the The Pampean aquifer. A total of 44 groundwater samples were collected from the shallow aquifers in NE of La Pampa province. Two rural areas covering an area of 600km2 in Quemú Quemú (QQ) and 300km2 in Intendente Alvear (IA) were investigated in the present study. Groundwater was circum-neutral to alkaline (pH 7.43-9.18), predominantly oxidizing (Eh ~0.24 V) with widely variable EC range (456-11,400 μS/cm). The major cation dissolved in groundwater was Na+, while the predominant anions were HCO3-, Cl- and SO42-, respectively. Water type in QQ was mostly Na-HCO3- while in IA, the composition differed between Na-HCO3- and Na-Cl-SO42- water types. Groundwater composition showed high degree of mineralization and high salinity evidenced by high EC. In discharge areas, high evaporation rates result in high salinity of shallow groundwater and visible salts incrustations on the surface of the lakes. Elevated concentrations of NO3- and PO43- observed in some wells indicated possible anthropogenic contamination. Total As concentration in groundwater from QQ ranged from 5.58 to 535 μg/L, where 94% of the wells exceeded the WHO standard limit for safe drinking water of 10 μg/L, and 56% of the wells exceeded the old Argentine standard limit of 50 μg/L. F- concentrations revealed heterogeneity and high concentrations in some wells (0.5-14.2 mg/L), 78% of samples in QQ study area exceeded the WHO standard limit of 1.5 mg/L. Under oxidizing conditions and neutral to alkaline pH, arsenate (AsV) species predominated, mainly in HAsO42- forms. As "hotspots" indicated locally contamination and correlated positively with F-, HCO3-, B and V and showed negative correlation with salinity, dissolved Fe, Al and Mn. The mechanisms involved in the mobilization of As in the shallow aquifers are controlled by the rise of pH, variations in Eh conditions and the presence of competitor ions (HCO3-, PO43-, Si, V oxyanions). Geochemical processes like adsorption/desorption, precipitation/dissolution and redox reactions may trigger to As mobilization in the shallow aquifers of La Pampa region.
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