| 1. |
- Mukherjee, A., et al.
(författare)
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Wide spread arsenic in deeper groundwater of western Bengal basin, West Bengal, India : Implications for sustainable alternate drinking water sources
- 2012
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Ingår i: Understanding the Geological and Medical Interface of Arsenic, As 2012. - : Taylor & Francis Group. ; , s. 522-525
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Konferensbidrag (refereegranskat)abstract
- Availability of safe drinking water is a major concern in the delta plains of the major Himalayan-Tibetan rivers in southern and southeastern Asia. While indiscriminate use of rivers and other surface water bodies for disposal of sewage and industrial waste has rendered them non-potable, natural, non-point source, elevated Arsenic (As) concentrations in groundwater exceeding the World Health Organization's (WHO) guideline value for drinking water of 0.01 mg/L have put millions of people at risk. Hence, finding an alternate, suitable and sustainable drinking-water source has been a priority in these areas. Generally, higher concentrations of dissolved As are found in groundwater of shallower aquifers and several studies have advocated deeper aquifers as a possible safe substitute. Using a composite hydrogeological approach, we demonstrate that regional-scale deeper groundwater As contamination in the western Bengal basin is dependent on the aquifer-aquitard framework and complex redox processes with partial equilibrium under natural flow conditions. Widespread deep irrigation pumping may be drawing shallower, contaminated groundwater down to greater depths. These findings have severe implications on finding alternate drinking water sources, in West Bengal, and adjoining areas of Bangladesh, with plausible similar geological and hydrogeological framework.
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| 2. |
- Kasiuliene, Alfreda, et al.
(författare)
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Hydrothermal carbonisation of peat-based spent sorbents loaded with metal(loid)s
- 2019
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Ingår i: Environmental Science and Pollution Research. - : Springer. - 0944-1344 .- 1614-7499. ; 26:23, s. 23730-23738
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Tidskriftsartikel (refereegranskat)abstract
- Hydrothermal carbonisation (HTC) is a wet and relatively low-temperature process where, under autogenous pressures, biomass undergoes a chain of reactions leading to the defragmentation of organic matter. As well as its other uses (e.g. for producing low-cost carbon-based nano-compounds), HTC is utilised for the treatment of wet wastes, such as manure and biosludge. This study aimed to determine if hydrothermal carbonisation is a feasible treatment method for spent sorbents that are highly enriched with arsenic, chromium, copper, and zinc. The chemical properties of hydrochar and process liquid were evaluated after HTC treatment, where peat-based spent sorbents were carbonised at 230 °C for 3 h. Analysis of Fourier transform-infrared spectra revealed that during HTC, the oxygenated bonds of ethers, esters, and carboxylic groups were cleaved, and low-molecular-weight organic fragments were dissolved in the process liquid. A large fraction of arsenic (up to 62%), copper (up to 25%), and zinc (up to 36%) were transferred from the solids into the process water. Leaching of these elements from the hydrochars increased significantly in comparison with the spent sorbents.
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| 3. |
- Amiri, Vahab, et al.
(författare)
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Mercury pollution in the coastal Urmia aquifer in northwestern Iran : potential sources, mobility, and toxicity
- 2021
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Ingår i: Environmental Science and Pollution Research. - : Springer Science and Business Media Deutschland GmbH. - 0944-1344 .- 1614-7499. ; 28:14, s. 17546-17562
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Tidskriftsartikel (refereegranskat)abstract
- The concentration of total dissolved mercury (HgT) in surface and groundwater resources in the coastal parts of Urmia aquifer (NW of Iran) was investigated to identify the possible sources and sinks of mercury and the geochemical mechanisms controlling its mobilization. The distribution of water samples on the Piper diagram demonstrates that most samples have the Ca-Mg-HCO3 facies. From 62 water samples collected in this area, one sample contained HgT concentrations exceeding the maximum contaminant level recommended by the WHO (6 μg/L). The principal component analysis (PCA) produced five principal components. The positive moderate correlation of HgT with EC, Cl, K, Mg, and Na indicated that the weathering of geological formations was one of the main sources of mercury in groundwater samples. Position of water samples in Eh-pH regions where microorganisms involved in mercury methylation and mineralization were potentially active demonstrated that the aquifer had undergone sulfate reduction and had reached the final stage of the terminal electron accepting process (TEAP) sequence in the methane production processes which are limited to only 37% of the water samples that have anaerobic conditions. Some Hg-bearing species are in nonequilibrium geochemical conditions. The supersaturation of water samples with magnetite and goethite indicated that these Fe-bearing minerals could act as the strong reducing agents for the reduction of Hg(II) to Hg(0).
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| 4. |
- Kasiuliene, Alfreda, et al.
(författare)
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Leaching of metal(loid)s from ashes of spent sorbent and stabilisation effect of calcium-rich additives
- 2020
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Ingår i: Environmental Science and Pollution Research. - : Springer. - 0944-1344 .- 1614-7499. ; 27:23, s. 29248-29256
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Tidskriftsartikel (refereegranskat)abstract
- Contaminated water with multiple contaminants, including As, Cr, Cu and Zn, was treated with a sorbent prepared by coating peat with Fe oxides. Because As has a relatively little explored market, the regeneration of the spent sorbent was not feasible. Meanwhile, the disposal of As wastes in landfills can cause landfill leachate treatment problems. Under the reducing conditions prevailing at landfills, As(V) is reduced to As(III), which is a toxic and more mobile form. In this study, incineration was explored as a management option to treat the spent sorbent that was loaded with As, Cr, Cu and Zn. The first objective of this study was to evaluate the leaching of these metal(loid)s from the ashes and compare it with the leaching from the spent sorbents before incineration. The second objective was to evaluate the leaching behaviour when the spent sorbent was co-incinerated with a Ca-rich additive (lime). To achieve these objectives, the obtained ashes were subjected to leaching tests, sequential extraction, and X-ray diffraction analyses. After the incineration, the ash content ranged from 9 to 19% of the initial mass of the spent sorbents. The leaching of As, Cu and Zn decreased compared with that from the spent sorbents before the thermal treatment because of the high incineration temperatures and/or co-incineration with lime. However, the leaching of Cr increased, which would hinder the disposal of the obtained ashes in a landfill because the limit value for disposal at a landfill for hazardous wastes was exceeded by 50 times. However, co-incineration with 10 wt% lime significantly decreased the leaching of Cr as a result of the formation of water-insoluble Ca-Cr compounds.
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| 5. |
- Kasiuliene, Alfreda, et al.
(författare)
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Treatment of metal (loid) contaminated solutions using iron-peat as sorbent : is landfilling a suitable management option for the spent sorbent?
- 2019
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Ingår i: Environmental Science and Pollution Research. - : Springer. - 0944-1344 .- 1614-7499. ; 26:21, s. 21425-21436
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Tidskriftsartikel (refereegranskat)abstract
- This study firstly aimed to investigate the potential of simultaneous metal (loid) removal from metal (oid) solution through adsorption on iron-peat, where the sorbent was made from peat and Fe by-products. Up-flow columns filled with the prepared sorbent were used to treat water contaminated with As, Cu, Cr, and Zn. Peat effectively adsorbed Cr, Cu, and Zn, whereas approximately 50% of inlet As was detected in the eluent. Iron-sand was effective only for adsorbing As, but Cr, Cu, and Zn were poorly adsorbed. Only iron-peat showed the simultaneous removal of all tested metal (loid)s. Metal (loid) leaching from the spent sorbent at reducing conditions as means to assess the behaviour of the spent sorbent if landfilled was also evaluated. For this purpose, a standardised batch leaching test and leaching experiment at reducing conditions were conducted using the spent sorbent. It was found that oxidising conditions, which prevailed during the standardised batch leaching test, could have led to an underestimation of redox-sensitive As leaching. Substantially higher amounts of As were leached out from the spent sorbents at reducing atmosphere compared with oxidising one. Furthermore, reducing environment caused As(V) to be reduced into the more-toxic As (III).
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| 6. |
- Kumar, Manish, et al.
(författare)
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First comparison of conventional activated sludge versus root-zone treatment for SARS-CoV-2 RNA removal from wastewaters : Statistical and temporal significance
- 2021
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Ingår i: Chemical Engineering Journal. - : Elsevier BV. - 1385-8947 .- 1873-3212. ; 425
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Tidskriftsartikel (refereegranskat)abstract
- In the initial pandemic phase, effluents from wastewater treatment facilities were reported mostly free from Severe Acute Respiratory Coronavirus 2 (SARS-CoV-2) RNA, and thus conventional wastewater treatments were generally considered effective. However, there is a lack of first-hand data on i) comparative efficacy of various treatment processes for SARS-CoV-2 RNA removal; and ii) temporal variations in the removal efficacy of a given treatment process in the backdrop of active COVID-19 cases. This work provides a comparative account of the removal efficacy of conventional activated sludge (CAS) and root zone treatments (RZT) based on weekly wastewater surveillance data, consisting of forty-four samples, during a two-month period. The average genome concentration was higher in the inlets of CAS-based wastewater treatment plant (WWTP) in the Sargasan ward (1.25 x 10(3) copies/L), than that of RZT-based WWTP (7.07 x 10(2) copies/L) in an academic institution campus of Gandhinagar, Gujarat, India. ORF 1ab and S genes appeared to be more sensitive to treatment i.e., significantly reduced (p < 0.05) than N genes (p > 0.05). CAS treatment exhibited better RNA removal efficacy (p = 0.014) than RZT (p = 0.032). Multivariate analyses suggested that the effective genome concentration should be calculated based on the presence/absence of multiple genes. The present study stresses that treated effluents are not always free from SARS-CoV-2 RNA, and the removal efficacy of a given WWTP is prone to exhibit temporal variability owing to variations in active COVID-19 cases in the vicinity and genetic material accumulation over the time. Disinfection seems less effective than the adsorption and coagulation processes for SARS-CoV-2 removal. Results stress the need for further research on mechanistic insight on SARS-CoV-2 removal through various treatment processes taking solid-liquid partitioning into account.
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| 7. |
- Paul, Seema, et al.
(författare)
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A shallow water numerical method for assessing impacts of hydrodynamics and nutrient transport processes on water quality values of Lake Victoria
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Lake Victoria is the world’s largest tropical lake and the third-largest water body, providing significant water resources for surrounding environments including the cultural, societal, and livelihood needs of people in its basin and along the White Nile. The aim of this study was to use decade-long time series of measured lake flow in the lake system and phosphorus deposition to develop a suitable numerical model based on shallow water equations (SWE) for assessing water quality in Lake Victoria, an increasingly important tool under climate variation. Different techniques were combined to identify a numerical model that included: i) a high-resolution SWE model to establish raindrop diffusion to trace pollutants; ii) a two-dimensional (2D) vertically integrated SWE model to establish lake surface flow and vertically transported wind speed flow acting on lake surface water by wind stress; and iii) a site-specific phosphorus deposition sub-model to calculate atmospheric deposition in the lake. A smooth (non-oscillatory) solution was obtained by applying a high-resolution scheme for a raindrop diffusion model. Analysis with the vertically integrated SWE model generated depth averages for flow velocity and associated changes in water level profile in the lake system and showed unidirectional whole lake wind blowing from the southwest to northeast. The atmospheric phosphorous deposition model enabled water value assessment for mass balances with different magnitudes of both inflows and outflows demonstrating annual total phosphorus at 13,500 tons concentrating at mid-lake western and eastern parts. The model developed here is simple and suitable for use in assessing flow changes and lake level changes and can serve as a tool in studies of lake bathymetry and nutrient and pollution transport processes. Our study opens towards refining models of complex shallow-water systems.
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| 8. |
- 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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| 9. |
- Bhattacharya, Prosun, 1962-, et al.
(författare)
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Tubewell platform color : Assessment of a tool for rapid screening of arsenic and manganese in well water
- 2012
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Ingår i: UNDERSTANDING THE GEOLOGICAL AND MEDICAL INTERFACE OF ARSENIC, AS 2012. - : CRC PRESS-TAYLOR & FRANCIS GROUP. ; , s. 515-518
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Konferensbidrag (refereegranskat)abstract
- This study attempts to make a statistical comparison between Tubewell (TW) platform color and the level of Arsenic (As) and Manganese (Mn) concentration in groundwater abstracted from a set of 423 Tubewells (TWs) in Chakdaha Block of Nadia District, West Bengal, India to validate platform color as a screening tool for both As and Mn in groundwater. The results indicate that water extracted from TWs with black colored platform in 93% cases was safe for As while water extracted from TWs with red colored platform is contaminated with As with 38% certainty, compared to drinking water standard of India (50 mu g/L). At this standard the respective efficiency, sensitivity and specificity of the tool are 65, 85 and 59%. If WHO drinking water guideline (10 mu g/L) is considered, the certainty increases to 73% and 84% respectively for black and red colored platform with respective efficiency, sensitivity and specificity values of 79, 77 and 81%. Furthermore, the black colored platform with 78% certainty indicates well water is enriched with Manganese (Mn), while red colored platform indicates water is low in Mn with 64% certainty evaluated against Indian national standard of 300 mu g/L. This study demonstrates that platform color can be potentially used as an initial screening tool for As and Mn, to assess the safe water acess for drinking purposes.
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| 10. |
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