1. |
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2. |
- Wilen, Britt-Marie, 1966, et al.
(author)
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Impacts of structural characteristics on activated sludge floc stability
- 2003
-
In: Water Research. - 0043-1354 .- 1879-2448. ; 37:15, s. 3632-3645
-
Journal article (peer-reviewed)abstract
- Activated sludge samples from seven full scale plants were investigated in order to determine the relationship between floc structure and floc stability. Floc stability was determined by shear sensitivity and floc strength. Floc structure was considered in terms of two size scales, the micro and macro-structure. The micro-structure refers to the organisation of the floc components, such as the individual microorganisms. The macro-structure refers to the overall floc. The floc macro-structure was characterized by filament index, sludge volume index (SVI), size, and fractal dimension. It had a significant impact on floc stability. Large and open flocs with low fractal dimensions, containing large numbers of filaments were more shear sensitive and had lower floc strength compared to small and dense flocs. Fluorescent in-situ hybridisation (FISH) analysis indicated that the organization of the bacterial cells might also have an affect on the floc stability.
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3. |
- Andersson, Anneli, et al.
(author)
-
Impact of temperature on nitrification in biological activated carbon (BAC) filters used for drinking water treatment
- 2001
-
In: Water Research. - 0043-1354 .- 1879-2448. ; 35:12, s. 2923-2934
-
Journal article (peer-reviewed)abstract
- The impact of temperature on nitrification in biological granular activated carbon (GAC) filters was evaluated in order to improve the understanding of the nitrification process in drinking water treatment. The study was conducted in a northern climate where very cold water temperatures (below 2°C) prevail for extended periods and rapid shifts of temperature are frequent in the spring and fall. Ammonia removals were monitored and the fixed nitrifying biomass was measured using a method of potential nitrifying activity. The impact of temperature was evaluated on two different filter media: an opened superstructure wood-based activated carbon and a closed superstructure activated carbon-based on bituminous coal. The study was conducted at two levels: pilot scale (first-stage filters) and full-scale (second-stage filters) and the results indicate a strong temperature impact on nitrification activity. Ammonia removal capacities ranged from 40 to 90% in pilot filters, at temperatures above 10°C, while more than 90% ammonia was removed in the full-scale filters for the same temperature range. At moderate temperatures (4–10°C), the first stage pilot filters removed 10–40% of incoming ammonia for both media (opened and closed superstructure). In the full-scale filters, a difference between the two media in nitrification performances was observed at moderate temperatures: the ammonia removal rate in the opened superstructure support (more than 90%) was higher than in the closed superstructure support (45%). At low temperatures (below 4°C) both media performed poorly. Ammonia removal capacities were below 30% in both pilot- and full-scale filters.
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4. |
- Andersson, Per, et al.
(author)
-
A rapid preconcentration method for multielement analysis of natural freshwaters
- 1991
-
In: Water Research. - 0043-1354 .- 1879-2448. ; 25:5, s. 617-620
-
Journal article (peer-reviewed)abstract
- This study describes an inexpensive and rapid preconcentration method which can be applied directly in the field. It is based on coprecipitation with magnesium hydroxide and has been applied for Al, Fe, Mn, Zn, Cu, Ni, V, Cr, Co, Cd, Be, Y, Sc and Yb in freshwaters. The method has been tested using inductively coupled plasma-atomic emission spectrometry (ICP-AES) by adding known amounts of metals to distilled water and natural freshwater. The detection limit for ICP-AES can be enhanced more than two orders of magnitude for Al, Y, Sc, Yb and approximately one order of magnitude for the other tested elements.
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5. |
- Du, Qing, et al.
(author)
-
Complexations in illite–fulvic acid–Cu2+ systems
- 1999
-
In: Water Research. - 0043-1354 .- 1879-2448. ; 33:3, s. 693-706
-
Journal article (peer-reviewed)abstract
- As part of an extended project to illustrate how heavy metals are complexed by natural aquatic particles, we conducted various experiments to study the adsorption of fulvic acid (FA) at aqueous illite surfaces and the complexation of heavy metal copper(II) in illite-FA bi-complexant systems. By analyzing batch adsorption and potentiometric titration data, we found that (i) the adsorption of FA by illite decreases with increases in pH values and its pH adsorption edge resembles those of SiO2-FA and montmorillonite-FA systems described by other researchers, (ii) it is possible to effectively simulate the complexation of Cu2+ ions in illite-FA bi-complexant systems by taking it to be an additive complexation of two mono-complexant systems (FA-Cu2+ and illite-Cu2+) and (iii) FA can inhibit the retention of heavy metals at solid surfaces by forming soluble complexes with metal ions. The above results and conclusions are supported by FT-IR analysis of various illite-FA-Cu2+ systems.
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6. |
- Grunditz, C., et al.
(author)
-
Development of nitrification inhibition assays using pure cultures of Nitrosomonas and Nitrobacter
- 2001
-
In: Water Research. - 0043-1354 .- 1879-2448. ; 35:2, s. 433-440
-
Journal article (peer-reviewed)abstract
- Restricted requirements for nitrogen reduction at wastewater treatment plants have increased the need for assays determining the inhibition of nitrification. In this paper, two new essays studying ammonia oxidation and nitrite oxidation, respectively, are presented. As test organisms, pure cultures of Nitrosomonas and Nitrobacter isolated from activated sludge are used. The assays are performed in test tubes where the bacteria are incubated with the compound or wastewater to be tested. The nitrification rate is measured during 4h and compared with reference samples. The test organisms were characterised with respect to temperature, pH and cell activity. Optimum temperature was 35 degreesC for Nitrosomonas and 38 degreesC for Nitrobacter; optimum pH was 8.1 for Nitrosomonas and 7.9 for Nitrobacter. There was a linear relationship between the nitrification rate and the cell concentration in the studied interval. The cell activity decreased slightly with storage time. A significant level of inhibition was calculated to 11% for the Nitrosomonas assay, and to 9% for the Nitrobacter assay. The assays are applicable to determination of nitrification inhibition in samples of industrial waste waters or influents of treatment plants, or chemical substances likely to be found in wastewater.
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7. |
- Johansson, Lena, 1967-, et al.
(author)
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Phosphate removal using blast furnace slags and opoka-mechanisms
- 2000
-
In: Water Research. - 0043-1354 .- 1879-2448. ; 34:1, s. 259-265
-
Journal article (peer-reviewed)abstract
- The abiotic sorption efficiency of on-site wastewater treatment systems can be improved by using a strongly sorbing filter material that, if it retains phosphorus (P) in a plant available way, can be used as fertiliser when P saturation is achieved. Two materials, blast furnace slag and the siliceous sedimentary rock opoka, have shown a high P sorption capacity and were included in a set of experiments to investigate the P retention mechanisms from model P-solution. Experiments focusing on the P sorption, capacity and calcium (Ca) and PO4 determination were carried out. The pH was also measured. The P sorption experiment showed that some slags were efficient P retainers, while the opoka was the least efficient P retainer. The pH decreased in all samples as a function of P addition. In the slag samples, the Ca concentration also decreased as a function of P addition, suggesting Ca-P precipitation as the major P removal mechanism for the slag. The Ca and PO4 speciation data ruled out the formation of amorphous calcium phosphates and/or octacalcium phosphate as the major P removal mechanism. However, the calculated ion activity products displayed clear evidence that hydroxyapatite had precipitated above a certain critical supersaturation limit. This would explain the poor P retention efficiency of the opoka samples in this study as the ion activity products were too low. The finding that direct hydroxyapatite formation is the predominant P removal mechanism might have important implications for their possible use as fertiliser due to the poor solubility of hydroxyapatite.
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8. |
- Jonsson, K., et al.
(author)
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Occurrence of nitrification inhibition in Swedish municipal wastewaters
- 2000
-
In: Water Research. - 0043-1354 .- 1879-2448. ; 34:9, s. 2455-2462
-
Journal article (peer-reviewed)abstract
- The occurrence of substances inhibiting nitrification in Swedish municipal wastewaters was investigated using three methods: a screening method based on activated sludge and two pure culture methods based on Nitrosomonas and Nitrobacter. Influent samples from 109 wastewater treatment plants collected every day during one specific week were investigated. The three test methods were also compared. The results of the screening method showed that about 60% of the plants received wastewater containing inhibitory substances, although only 4% had considerable inhibition (>20%). With the two pure culture methods, inhibition was found at about 45% of the plants investigated, with considerable inhibition found at 13% and 20% of the plants with the Nitrosomonas and the Nitrobacter methods, respectively. The limit of detection was determined to be 5% inhibition for the screening method, 11% inhibition for the Nitrosomonas method and 13% inhibition for the Nitrobacter method. The pure culture methods found more samples strongly inhibitory or stimulating than the screening method. The highest correlation between the inhibition results from the three methods was found between the screening method and the Nitrosomonas method. It was also shown for sludge from several activated sludge treatment plants, that they were adapted to the toxic compounds present in the influent. At high inhibition this acclimatisation was less pronounced. No correlation was found for any of the methods between the inhibition and parameters such as the size of the plant, the geographic location, the content of ammonia, COD or conductivity in the influent, the presence of leachate or the percentage of industrial wastewater in the influent, or types of industries in the catchment area. However, the constantly highest inhibition was found at a plant with a large number of different industries connected. Any clear pattern for the variation of inhibition during the week was not found.
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9. |
- Jonsson, Susanne, 1965-, et al.
(author)
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Mono- and diesters from o-phthalic acid in leachates from different European landfills
- 2003
-
In: Water Research. - 0043-1354 .- 1879-2448. ; 37:3, s. 609-617
-
Journal article (peer-reviewed)abstract
- Leachates from 17 different landfills in Europe were analysed with respect to phthalates, i.e. phthalic acid diesters (PAEs) and their degradation products phthalic acid monoesters (PMEs) and ortho-phthalic acid (PA). Diesters are ubiquitous and the human possible exposure and potential to human health and environment has put them in focus. The aim of this study was to elucidate whether monoesters and phthalic acid could be traced in landfill leachates and in what concentrations they may be found. The results showed that phthalates were present in the majority of the leachates investigated. The monoesters appeared from 1 to 20 μg/L and phthalic acid 2–880 μg/L (one divergent value of 19 mg phthalic acid/L). Their parental diesters were observed from 1 to 460 μg/L. These observed occurrences of degradation products, of all diesters studied, support that they are degraded under the landfill conditions covered by this study. Thus, we have presented strong evidences to conclude that microorganisms in landfills degrade diesters released from formulations in a variety of products, including polyvinyl chloride (PVC) species.
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10. |
- Larsson, Per, et al.
(author)
-
Microbial mineralization of chlorinated phenols and biphenyls in sediment/water systems humic and clear-water lakes
- 1989
-
In: Water Research. - : Elsevier BV. - 0043-1354 .- 1879-2448. ; 23:9, s. 1081-1085
-
Journal article (peer-reviewed)abstract
- The microbial mineralization of three chlorophenols and a PCB mixture was studied using natural bacterial assemblages in laboratory model systems. The systems consisted of water and surface sediment from two lake types: one with a high content of humic substances and the other with a low content. Aerobic mineralization of the 14C-ring-labelled compounds was determined as production of 14CO2 in the systems. The mineralization rates of 3,4-dichlorophenol and 2,4,5-trichlorophenol were higher in humic cultures whereas pentachlorophenol showed higher rates in clear-water cultures. Mineralization of PCBs in the systems was low. Compared with microbial mineralization rates in cultures containing only lake water, the addition of sediment resulted in a decrease in DCP and TCP mineralization. Pentachlorophenol was mineralized at considerably higher rates in the presence of sediment.
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11. |
- Mersiowsky, I., et al.
(author)
-
Fate of plasticised PVC products under landfill conditions : A laboratory-scale landfill simulation reactor study
- 2001
-
In: Water Research. - 0043-1354 .- 1879-2448. ; 35:13, s. 3063-3070
-
Journal article (peer-reviewed)abstract
- The long-term behaviour of plasticised PVC products was investigated in laboratory-scale landfill simulation reactors. The examined products included a cable material and a flooring with different combinations of plasticisers. The objective of the study was to assess whether a degradation of the PVC polymer or a loss of plasticisers occurred under landfill conditions. A degradation of the polymer matrix was not observed. The contents of plasticisers in aged samples was determined and compared to the respective original products. The behaviour of the various plasticisers was found to differ significantly. Losses of DEHP and BBP from the flooring were too low for analytical quantification. No loss of DIDP from the cable was detectable, whereas DINA in the same product showed considerable losses of up to 70% compared to the original contents. These deficits were attributable to biodegradation rather than leaching. There was no equivalent release of plasticisers into the leachate. Copyright © 2001 Elsevier Science Ltd.
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12. |
- Nilsson, Per, et al.
(author)
-
Hydrodynamic control of nitrogen and phosphorus turnover in an eutrophicated estuary in the Baltic
- 2002
-
In: Water Research. - 0043-1354 .- 1879-2448. ; 36:18, s. 4616-4626
-
Journal article (peer-reviewed)abstract
- The turnover of phosphorus and nitrogen have been studied in a low salinity estuary in the Bothnian Sea. The estuary, Gardsfjarden, has a high loading of nutrients from a pulp and paper mill which supplies the estuary with three times the annual natural input of phosphorus and nitrogen, respectively. The turnover of nutrients was to a great extent determined by hydrodynamic variations. During periods of intense resuspension there was a net export of particulate bound nutrients from the estuary to the sea but since these periods were short there was an overall net retention of particulate nutrients. The estuary was a source for dissolved phosphorus to the sea. The major source of phosphorus export was release of dissolved P from anoxic sediments. Gardsfjarden was a sink for dissolved nitrogen which most likely escaped the estuary by denitrification. Nitrate was supplied by degradation of particulate organic nitrogen but the main source was import from the sea.
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13. |
- Ottoson, Jakob, et al.
(author)
-
Faecal contamination of greywater and associated microbial risks
- 2003
-
In: Water Research. - 0043-1354 .- 1879-2448. ; 37:3, s. 645-655
-
Journal article (peer-reviewed)abstract
- The faecal contamination of greywater in a local treatment system at Vibyasen, north of Stockholm, Sweden was quantified using faecal indicator bacteria and chemical biomarkers. Bacterial indicator densities overestimated the faecal load by 100-1000-fold when compared to chemical biomarkers. Based on measured levels of coprostanol, the faecal load was estimated to be 0.04 g person(-1) day(-1). Prevalence of pathogens in the population and the faccal load were used to form the basis of a screening-level quantitative microbial risk assessment (QMRA) that was undertaken for rotavirus, Salmonella typhimurium, Campylobacter jejuni, Giardia lamblia and Cryptosporidium parvum. The different exposure scenarios simulated-direct contact, irrigation of sport fields and groundwater recharge-gave unacceptably high rotavirus risks (0.04
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14. |
- Ringqvist, L., et al.
(author)
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Poorly humified peat as an adsorbent for metals in wastewater
- 2002
-
In: Water Research. - 0043-1354 .- 1879-2448. ; 36:9, s. 2394-2404
-
Journal article (peer-reviewed)abstract
- Metal adsorption and surface charge determinations were performed previously on well-characterised Sphagnum and Carex peat samples. The aim of this investigation was to determine metal adsorption from complex wastewaters onto these peat samples and compare it to the adsorption onto peat granules, clinoptilolite, glauconite and a flue dust from steel production. A sulphide mine leachate, a landfill leachate and a laundry wastewater were chosen, giving a variation in pH, ionic strength, total organic carbon and concentrations of metals. Metal adsorption was determined in batch and column experiments. The wastewater composition was of great importance for metal removal efficiency, mainly due to the difference in dominating metal species. In the sulphide mine leachate, containing free metal ions, a high metal adsorption was observed onto both peat and inorganic adsorbents. In the landfill leachate the metals formed carbonate and organic complexes and a low metal removal was achieved. Contrary to the leachates, the laundry wastewater contained suspended particles. The high amount of metals removed, 80% of the Cu and 30-60% of the Zn concentration, was probably withdrawn bound to the particle fraction. The highest removal of metal ions was obtained in the sulphide mine leachate with Carex peat, removing 97-99% of the Zn and 85-100% of the Cu content. The Sphagnum peat sample removed 37-77% of the Zn and 80-100% of the Cu content. The differences found between Sphagnum and Carex peat were attributed to the original chemistry of the plant material and the habitat conditions at the time of peat formation. Generally, the combination of glauconite or clinoptilolite with the peat samples in column experiments gave a minor improvement in metal removal.
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15. |
- Särner, Erik
(author)
-
Removal of Dissolved and Particulated Organic Matter in High-Rate Trickling Filters
- 1981
-
In: Water Research. - : Elsevier BV. - 0043-1354 .- 1879-2448. ; 15:6, s. 671-678
-
Journal article (peer-reviewed)abstract
- The biochemical reaction is normally assumed to control the over-all purification rate in a trickling filter and the most commonly used mathematical models are based on first-order reaction kinetics. The substrate is assumed to consist of one single substance, normally measured as the biochemical or chemical oxygen demand.The result of this investigation indicates that the removal of dissolved organic matter in high-rate trickling filters is disturbed if fine suspended and colloidal matter is present in the influent to the filters. This is an important factor to be considered and further research on the influence of the substrate composition on the purification rate is needed. The result also indicates that liquid film diffusion might control the substrate removal rate. The efficiency of the filter could not be related to the specific surface of the plastic packing used. The configuration of the packing is obviously a more relevant factor, possibly affecting the turbulence and/or the wetted area.
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16. |
- Tenno, Robert A., et al.
(author)
-
Activated sludge concentration dynamics
- 1994
-
In: Water Research. - : Elsevier BV. - 0043-1354 .- 1879-2448. ; 28:2, s. 491-493
-
Journal article (peer-reviewed)abstract
- The relationship between activated sludge concentration in the aeration and settling tank is determined on the basis of settling process characteristics. The relationship is used for description of the activated sludge concentration and stock dynamics in the aeration and settling tank. A limit value for maximization of activated sludge concentration is determined
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17. |
- Tenno, Robert A., et al.
(author)
-
Online identification of activated sludge settling properties
- 1995
-
In: Water Research. - 0043-1354 .- 1879-2448. ; 29:11, s. 2587-2590
-
Journal article (peer-reviewed)abstract
- Activated sludge settling properties can be characterised with two time-varying parameters. A simple method is presented for online identification of these parameters. The method is obtained as an exact solution of the filtration problem; it is obtained on the basis of the settling process description and the parameters variation process description. The method is suitable for practical application. It is a more exact solution of the identification problem than the alternative regression analysis method. An easily implementable system is proposed for automatic characterisation of the sludge settling properties
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18. |
- Wang, Feiyue, et al.
(author)
-
Surface properties of natural aquatic sediments
- 1997
-
In: Water Research. - 0043-1354 .- 1879-2448. ; 31:7, s. 1796-1800
-
Journal article (peer-reviewed)abstract
- Eleven geographically and hydrologically diverse sediment samples were collected from major rivers of China and determined for the surface properties. The results indicate the sediments have a large variation in surface area (6.9-16.0 m(2)/g of SSA(N2), 35.6-73.2 m(2)/g Of SSA(CPB), surface site density (10.3-149.8 mu mol/g) and surface acidity constants (1.56-2.50 of pK(s.a1)(int), and 3.75-5.58 of pK(s.a2)(int)) but a small difference in PZSE (3.0-4.0). Within the pH range 3.0-9.0, all sediments present negative surface charges. Their surface charge distribution curves with pH extend between these of SiO2, montmorillonite. kaolinite, alpha-MnO2, calcite and gamma-Al2O3;. Correlation analysis reveals that surface area and surface site density of the sediments are correlated strongly with reactive and amorphous iron oxides, total aluminum, clay and total organic carbon, while surface acidity constants, PZSE and the permanent structural charge only show a weak correlation with total aluminum in the sediments.
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19. |
- Abel, Sebastian, et al.
(author)
-
Mixing and capping techniques for activated carbon based sediment remediation Efficiency and adverse effects for Lumbriculus variegatus
- 2017
-
In: Water Research. - : Elsevier BV. - 0043-1354 .- 1879-2448. ; 114, s. 104-112
-
Journal article (peer-reviewed)abstract
- Activated carbon (AC) has been proven to be highly effective for the in-situ remediation of sediments contaminated with a wide range of hydrophobic organic contaminants (HOCs). However, adverse biological effects, especially to benthic organisms, can accompany this promising remediation potential. In this study, we compare both the remediation potential and the biological effects of several AC materials for two application methods: mixing with sediment (MIX) at doses of 0.1 and 1.0% based on sediment dw and thin layer capping (TLC) with 0.6 and 1.2 kg AC/m(2). Significant dose dependent reductions in PCB bioaccumulation in Lumbriculus variegatus of 35-93% in MIX treatments were observed. Contaminant uptake in TLC treatments was reduced by up to 78% and differences between the two applied doses were small. Correspondingly, significant adverse effects were observed for L. variegatus whenever AC was present in the sediment. The lowest application dose of 0.1% AC in the MIX system reduced L variegatus growth, and 1.0% AC led to a net loss of organism biomass. All TLC treatments let to a loss of biomass in the test organism. Furthermore, mortality was observed with 1.2 kg ACim(2) doses of pure AC for the TLC treatment. The addition of clay (Kaolinite) to the TLC treatments prevented mortality, but did not decrease the loss in biomass. While TLC treatments pose a less laborious alternative for AC amendments in the field, the results of this study show that it has lower remediation potential and could be more harmful to the benthic fauna.
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20. |
- Adediran, Gbotemi, et al.
(author)
-
Micro and nano sized particles in leachates from agricultural soils: Phosphorus and sulfur speciation by X-ray micro-spectroscopy
- 2021
-
In: Water Research. - : Elsevier BV. - 0043-1354 .- 1879-2448. ; 189
-
Journal article (peer-reviewed)abstract
- Colloids and nanoparticles leached from agricultural land are major carriers of potentially bioavailable nutrients with high mobility in the environment. Despite significant research efforts, accurate knowledge of macronutrients in colloids and nanoparticles is limited. We used multi-elemental synchrotron X-ray fluorescence (XRF) microscopy with multivariate spatial analysis and X-ray atomic absorption near-edge structure (XANES) spectroscopy at the P and S K-edges, to study the speciation of P and S in two fractions of leached particles, >0.45 and <0.45 mu m respectively, collected from four tile-drained agricultural sites in Sweden. P K-edge XANES showed that organic P, followed by P adsorbed to surfaces of aluminum-bearing particles were the most common forms of leached P. Iron-bound P (Fe-P) forms were generally less abundant (0-30 % of the total P). S K-edge XANES showed that S was predominantly organic, and a relatively high abundance of reduced S species suggests that redox conditions were adverse to the persistence of P bound to Fe-bearing colloids in the leachates. Acid ammonium-oxalate extractions suggested that P associated with Al and Fe (Al-P and Fe-P) in most cases could be explained by the adsorption capacity of non-crystalline (oxalate-extractable) oxides of Al and Fe. These results improve our understanding of particulate P and S speciation in the vadose zone and helps in developing effective technologies for mitigating colloidal driven eutrophication of water bodies near agricultural land. (C) 2020 The Author(s). Published by Elsevier Ltd.
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21. |
- Agstam-Norlin, O., et al.
(author)
-
A 25-year retrospective analysis of factors influencing success of aluminum treatment for lake restoration
- 2021
-
In: Water Research. - : Elsevier BV. - 0043-1354 .- 1879-2448. ; 200
-
Journal article (peer-reviewed)abstract
- For more than 50 years, aluminum (Al)-salts have been used with varying degrees of success to inactivate excess mobile phosphorus (P) in lake sediments and restore lake water quality. Here, we analyzed the factors influencing effectiveness and longevity of Al-treatments performed in six Swedish lakes over the past 25 years. Trends in post-treatment measurements of total phosphorus (TP), Chlorophyll a (Chl_a), Secchi disk depth (SD) and internal P loading rates (Li) were analyzed and compared to pre-treatment conditions. All measured water quality parameters improved significantly during at least the first 4 years post-treatment and determination of direct effects of Al-treatment on sediment P release (Li) was possible for three lakes. Improvements in TP (-29 to -80%), Chl_a (-50 to -78%), SD (7 to 121%) and Li (-68 to -94%) were observed. Treatment longevity, determined via decreases in surface water TP after treatment, varied from 7 to >47 years. Lake type, Al dose, and relative watershed area were related to longevity. In addition, greater binding efficiency between Al and P was positively related to treatment longevity, which has not previously been shown. Our findings also demonstrate that adequate, long-term monitoring programs, including proper determination of external loads, are crucial to document the effect of Al-treatment on sediment P release and lake water quality.
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22. |
- Agstam, Oskar, et al.
(author)
-
Optimization of aluminum treatment efficiency to control internal phosphorus loading in eutrophic lakes
- 2020
-
In: Water Research. - : Elsevier BV. - 0043-1354 .- 1879-2448. ; 185
-
Journal article (peer-reviewed)abstract
- Historical accumulation of phosphorus (P) in lake sediment often contributes to and sustains eutrophic conditions in lakes, even when external sources of P are reduced. The most cost-effective and commonly used method to restore the balance between P and P-binding metals in the sediment is aluminum (Al) treatment. The binding efficiency of Al, however, has varied greatly among treatments conducted over the past five decades, resulting in substantial differences in the amount of P bound per unit Al. We analyzed sediment from seven previously Al treated Swedish lakes to investigate factors controlling binding efficiency. In contrast to earlier work, lake morphology was negatively correlated to binding efficiency, meaning that binding efficiency was higher in lakes with steeply sloping bathymetry than in lakes with more gradually sloping bottoms. This was likely due to Al generally being added directly into the sediment, and not to the water column. Higher binding efficiencies were detected when Al was applied directly into the sediment, whereas the lowest binding efficiency was detected where Al was instead added to the water column. Al dose, mobile sediment P and lake morphology together explained 87% of the variation in binding efficiency among lakes where Al was added directly into the sediment. This led to the development of a model able to predict the optimal Al dose to maximize binding efficiency based on mobile sediment P mass and lake morphology. The predictive model can be used to evaluate cost-effectiveness and potential outcomes when planning Al-treatment using direct sediment application to restore water quality in eutrophic lakes.
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23. |
- Ahlgren, Joakim, et al.
(author)
-
Biogenic phosphorus in oligotropic mountain lake sediments: Differences in composition measured with NMR spectroscopy
- 2006
-
In: Water Research. - Uppsala Univ, Dept Phys & Analyt Chem, S-75124 Uppsala, Sweden. Univ So Denmark, Inst Biol, DK-5230 Odense M, Denmark. Uppsala Univ, Dept Organ & Biol Chem, S-75123 Uppsala, Sweden. Uppsala Univ, Dept Ecol & Evolut, EBC, S-75236 Uppsala, Sweden. : Elsevier BV. - 0043-1354 .- 1879-2448. ; :40, s. 3705-3712
-
Journal article (peer-reviewed)
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24. |
- Ahlgren, Joakim, et al.
(author)
-
Release of Organic P Forms from Lake Sediments
- 2011
-
In: Water Research. - : Elsevier BV. - 0043-1354 .- 1879-2448. ; 45:2, s. 565-572
-
Journal article (peer-reviewed)abstract
- The effects of different physical and chemical conditions on the decomposition and release of organic and inorganic P compound groups from the sediment of Lake Erken were investigated in a series of laboratory experiments. Conditions investigated were temperature, oxygen level, and the effects of additions of carbon substrate (glucose) and poison (formalin). The effects on the P compound groups were determined by measurements with 31P NMR before and after the experiments, as well as analysis of P in effluent water throughout the experiment. Phosphate analysis of the effluent water showed that oxygen level was the most influential in terms of release rates, with the sediments under anoxic conditions generally releasing more phosphate than the other treatments. 31P NMR showed that the various treatments did influence the P compound group composition of the sediment. In particular, the addition of glucose led to a decrease in orthophosphate and polyphosphate while the addition of formalin led to a decrease in phosphorus lipids, DNAphosphate and polyphosphate. Oxic conditions resulted in an increase in polyphosphates, and anoxic conditions in a decrease in these. Temperature did not seem to affect the composition significantly.
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25. |
- Ahlinder, Jon, et al.
(author)
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Upstream land use with microbial downstream consequences : iron and humic substances link to Legionella spp
- 2024
-
In: Water Research. - : Elsevier. - 0043-1354 .- 1879-2448. ; 256
-
Journal article (peer-reviewed)abstract
- Intensified land use can disturb water quality, potentially increasing the abundance of bacterial pathogens, threatening public access to clean water. This threat involves both direct contamination of faecal bacteria as well as indirect factors, such as disturbed water chemistry and microbiota, which can lead to contamination. While direct contamination has been well described, the impact of indirect factors is less explored, despite the potential of severe downstream consequences on water supply. To assess direct and indirect downstream effects of buildings, farms, pastures and fields on potential water sources, we studied five Swedish lakes and their inflows. We analysed a total of 160 samples in a gradient of anthropogenic activity spanning four time points, including faecal and water-quality indicators. Through species distribution modelling, Random Forest and network analysis using 16S rRNA amplicon sequencing data, our findings highlight that land use indirectly impacts lakes via inflows. Land use impacted approximately one third of inflow microbiota taxa, in turn impacting âŒ20â50 % of lake taxa. Indirect effects via inflows were also suggested by causal links between e.g. water colour and lake bacterial taxa, where this influenced the abundance of several freshwater bacteria, such as Polynucleobacter and Limnohabitans. However, it was not possible to identify direct effects on the lakes based on analysis of physiochemical- or microbial parameters. To avoid potential downstream consequences on water supply, it is thus important to consider possible indirect effects from upstream land use and inflows, even when no direct effects can be observed on lakes. Legionella (a genus containing bacterial pathogens) illustrated potential consequences, since the genus was particularly abundant in inflows and was shown to increase by the presence of pastures, fields, and farms. The approach presented here could be used to assess the suitability of lakes as alternative raw water sources or help to mitigate contaminations in important water catchments. Continued broad investigations of stressors on the microbial network can identify indirect effects, avoid enrichment of pathogens, and help secure water accessibility.
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26. |
- Ahmad, Arslan, et al.
(author)
-
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
-
In: Water Research. - : Elsevier. - 0043-1354 .- 1879-2448. ; 161, s. 505-516
-
Journal article (peer-reviewed)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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27. |
- Ahmad, Arslan, et al.
(author)
-
Deep-dive into iron-based co-precipitation of arsenic : A review of mechanisms derived from synchrotron techniques and implications for groundwater treatment
- 2024
-
In: Water Research. - : Elsevier Ltd. - 0043-1354 .- 1879-2448. ; 249
-
Research review (peer-reviewed)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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28. |
- Ahmad, Arslan, et al.
(author)
-
Mobility and redox transformation of arsenic during treatment of artificially recharged groundwater for drinking water production
- 2020
-
In: Water Research. - : Elsevier. - 0043-1354 .- 1879-2448. ; 178
-
Journal article (peer-reviewed)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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29. |
- Ahrens, Lutz
(author)
-
Drinking water nanofiltration with concentrate foam fractionation-A novel approach for removal of per- and polyfluoroalkyl substances (PFAS)
- 2023
-
In: Water Research. - : Elsevier BV. - 0043-1354 .- 1879-2448. ; 232
-
Journal article (peer-reviewed)abstract
- Per-and polyfluoroalkyl substances (PFAS) are recognized as persistent pollutants that have been found in drinking water sources on a global scale. Semi-permeable membrane treatment processes such as reverse osmosis and nanofiltration (NF) have been shown effective at removing PFAS, however, disposal of PFAS laden concentrate is problematic. Without treatment of the concentrate, PFAS is released into the environment. The present work examined a novel PFAS removal scheme for drinking water using NF filtration with treatment of the resulting NF concentrate via foam fractionation (FF) with and without co-surfactants. The NF-pilot removed 98% of PFAS from AFFF contaminated groundwater producing permeate with 1.4 ng L-1 total PFAS. Using FF resulted in EPFAS removal efficiency of 90% from the NF concentrate and with improved removal of 94% with addition of cationic co-surfactant. The resulting foamate composed approximately 2% of the NF feedwater volume and contained greater than 3000 ng L-1 PFAS or 41 times greater than the NF feedwater. Addition of the cationic co-surfactant to the FF process resulted in increased removal efficiency of the shorter chain PFAS, specifically 37% for PFPeA, 9% for PFHxA, and 34% for PFBS thus attaining 59%, 99% and 96% removal efficiency, respectively. PFOA, PFPeS, PFHxS, PFOS each attained 99% FF removal with or without co-surfactant addition.
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30. |
- Almstrand, Robert
(author)
-
Spatial impacts of inorganic ligand availability and localized microbial community structure on mitigation of zinc laden mine water in sulfate-reducing bioreactors
- 2017
-
In: Water Research. - : Elsevier BV. - 0043-1354 .- 1879-2448. ; 115, s. 50-59
-
Journal article (peer-reviewed)abstract
- Sulfate-reducing bioreactors (SRBRs) represent a passive, sustainable, and long-term option for mitigating mining influenced water (MIW) during release. Here we investigate spatial zinc precipitation profiles as influenced by substrate differentiation, inorganic ligand availability (inorganic carbon and sulfide), and microbial community structure in pilot-scale SRBR columns fed with sulfate and zinc-rich MIW. Through a combination of aqueous sampling, geochemical digests, electron microscopy and energy-dispersive x-ray spectroscopy, we were able to delineate zones of enhanced zinc removal, identify precipitates of varying stability, and discern the temporal and spatial evolution of zinc, sulfur, and calcium associations. These geochemical insights revealed spatially variable immobilization regimes between SRBR columns that could be further contrasted as a function of labile (alfalfa-dominated) versus recalcitrant (woodchip-dominated) solid-phase substrate content. Both column subsets exhibited initial zinc removal as carbonates; however precipitation in association with labile substrates was more pronounced and dominated by metal-sulfide formation in the upper portions of the down flow columns with micrographs visually suggestive of sphalerite (ZnS). In contrast, a more diffuse and lower mass of zinc precipitation in the presence of gypsum-like precipitates occurred within the more recalcitrant column systems. While removal and sulfide-associated precipitation were spatially variable, whole bacterial community structure (ANOSIM) and diversity estimates were comparatively homogeneous. However, two phyla exhibited a potentially selective relationship with a significant positive correlation between the ratio of Firmicutes to Bacteroidetes and sulfide-bound zinc. Collectively these biogeochemical insights indicate that depths of maximal zinc sulfide precipitation are temporally dynamic, influenced by substrate composition and broaden our understanding of bio-immobilized zinc species, microbial interactions and potential operational and monitoring tools in these types of passive bioreactors. (C) 2017 Elsevier Ltd. All rights reserved.
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31. |
- Alygizakis, Nikiforos, et al.
(author)
-
Making waves: The NORMAN antibiotic resistant bacteria and resistance genes database (NORMAN ARB&ARG)–An invitation for collaboration to tackle antibiotic resistance
- 2024
-
In: Water Research. - : Elsevier Ltd. - 0043-1354 .- 1879-2448. ; 257
-
Research review (peer-reviewed)abstract
- With the global concerns on antibiotic resistance (AR) as a public health issue, it is pivotal to have data exchange platforms for studies on antibiotic resistant bacteria (ARB) and antibiotic resistance genes (ARGs) in the environment. For this purpose, the NORMAN Association is hosting the NORMAN ARB&ARG database, which was developed within the European project ANSWER. The present article provides an overview on the database functionalities, the extraction and the contribution of data to the database. In this study, AR data from three studies from China and Nepal were extracted and imported into the NORMAN ARB&ARG in addition to the existing AR data from 11 studies (mainly European studies) on the database. This feasibility study demonstrates how the scientific community can share their data on AR to generate an international evidence base to inform AR mitigation strategies. The open and FAIR data are of high potential relevance for regulatory applications, including the development of emission limit values / environmental quality standards in relation to AR. The growth in sharing of data and analytical methods will foster collaboration on risk management of AR worldwide, and facilitate the harmonization in the effort for identification and surveillance of critical hotspots of AR. The NORMAN ARB&ARG database is publicly available at: https://www.norman-network.com/nds/bacteria/.
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32. |
- Anbalagan, Anbarasan, et al.
(author)
-
Influence of hydraulic retention time on indigenous microalgae and activated sludge process
- 2016
-
In: Water Research. - : Elsevier BV. - 0043-1354 .- 1879-2448. ; 91, s. 277-284
-
Journal article (peer-reviewed)abstract
- Integration of the microalgae and activated sludge (MAAS) process in municipal wastewater treatment and biogas production from recovered MAAS was investigated by studying the hydraulic retention time (HRT) of semi-continuous photo-bioreactors. An average total nitrogen (TN) removal efficiency (RE) of maximum 81.5 ± 5.1 and 64.6 ± 16.2% was achieved at 6 and 4 days HRT. RE of total phosphorous (TP) increased slightly at 6 days (80 ± 12%) HRT and stabilized at 4 days (56 ± 5%) and 2 days (55.5 ± 5.5%) HRT due to the fluctuations in COD and N/P mass ratio of the periodic wastewater. COD and organic carbon were removed efficiently and a rapidly settleable MAAS with a sludge volume index (SVI_10) of less than 117 mL g-1 was observed at all HRTs. The anaerobic digestion of the untreated MAAS showed a higher biogas yield of 349 ± 10 mL g VS-1 with 2 days HRT due to a low solids retention time (SRT). Thermal pretreatment of the MAAS (120 °C, 120 min) did not show any improvement with biogas production at 6 days (269 ± 3 (untreated) and 266 ± 16 (treated) mL gVS-1), 4 days (258 ± 11(untreated) and 263 ± 10 (treated) mL gVS-1) and 2 days (308 ± 19 mL (treated) gVS-1) HRT. Hence, the biogas potential tests showed that the untreated MAAS was a feasible substrate for biogas production. Results from this proof of concept support the application of MAAS in wastewater treatment for Swedish conditions to reduce aeration, precipitation chemicals and CO2 emissions.
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33. |
- Arnell, Magnus, et al.
(author)
-
Modelling anaerobic co-digestion in Benchmark Simulation Model No. 2 : Parameter estimation, substrate characterisation and plant-wide integration
- 2016
-
In: Water Research. - : Elsevier BV. - 0043-1354 .- 1879-2448. ; 98, s. 138-146
-
Journal article (peer-reviewed)abstract
- Anaerobic co-digestion is an emerging practice at wastewater treatment plants (WWTPs) to improve the energy balance and integrate waste management. Modelling of co-digestion in a plant-wide WWTP model is a powerful tool to assess the impact of co-substrate selection and dose strategy on digester performance and plant-wide effects. A feasible procedure to characterise and fractionate co-substrates COD for the Benchmark Simulation Model No. 2 (BSM2) was developed. This procedure is also applicable for the Anaerobic Digestion Model No. 1 (ADM1). Long chain fatty acid inhibition was included in the ADM1 model to allow for realistic modelling of lipid rich co-substrates. Sensitivity analysis revealed that, apart from the biodegradable fraction of COD, protein and lipid fractions are the most important fractions for methane production and digester stability, with at least two major failure modes identified through principal component analysis (PCA). The model and procedure were tested on bio-methane potential (BMP) tests on three substrates, each rich on carbohydrates, proteins or lipids with good predictive capability in all three cases. This model was then applied to a plant-wide simulation study which confirmed the positive effects of co-digestion on methane production and total operational cost. Simulations also revealed the importance of limiting the protein load to the anaerobic digester to avoid ammonia inhibition in the digester and overloading of the nitrogen removal processes in the water train. In contrast, the digester can treat relatively high loads of lipid rich substrates without prolonged disturbances.
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34. |
- Barrera, Ernesto L, et al.
(author)
-
Modeling the anaerobic digestion of cane-molasses vinasse: Extension of the Anaerobic Digestion Model No. 1 (ADM1) with sulfate reduction for a very high strength and sulfate rich wastewater.
- 2015
-
In: Water Research. - : Elsevier BV. - 1879-2448 .- 0043-1354. ; 71, s. 42-54
-
Journal article (peer-reviewed)abstract
- This research presents the modeling of the anaerobic digestion of cane-molasses vinasse, hereby extending the Anaerobic Digestion Model No. 1 with sulfate reduction for a very high strength and sulfate rich wastewater. Based on a sensitivity analysis, four parameters of the original ADM1 and all sulfate reduction parameters were calibrated. Although some deviations were observed between model predictions and experimental values, it was shown that sulfates, total aqueous sulfide, free sulfides, methane, carbon dioxide and sulfide in the gas phase, gas flow, propionic and acetic acids, chemical oxygen demand (COD), and pH were accurately predicted during model validation. The model showed high (±10%) to medium (10%-30%) accuracy predictions with a mean absolute relative error ranging from 1% to 26%, and was able to predict failure of methanogenesis and sulfidogenesis when the sulfate loading rate increased. Therefore, the kinetic parameters and the model structure proposed in this work can be considered as valid for the sulfate reduction process in the anaerobic digestion of cane-molasses vinasse when sulfate and organic loading rates range from 0.36 to 1.57 kg [Formula: see text] m(-3) d(-1) and from 7.66 to 12 kg COD m(-3) d(-1), respectively.
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35. |
- Been, Frederic, et al.
(author)
-
Risk-based prioritization of suspects detected in riverine water using complementary chromatographic techniques
- 2021
-
In: Water Research. - : Elsevier BV. - 0043-1354 .- 1879-2448. ; 204
-
Journal article (peer-reviewed)abstract
- Surface waters are widely used as drinking water sources and hence their quality needs to be continuously monitored. However, current routine monitoring programs are not comprehensive as they generally cover only a limited number of known pollutants and emerging contaminants. This study presents a risk-based approach combining suspect and non-target screening (NTS) to help extend the coverage of current monitoring schemes. In particular, the coverage of NTS was widened by combining three complementary separations modes: Reverse phase (RP), Hydrophilic interaction liquid chromatography (HILIC) and Mixed-mode chromatography (MMC). Suspect lists used were compiled from databases of relevant substances of very high concern (e.g., SVHCs) and the concentration of detected suspects was evaluated based on ionization efficiency prediction. Results show that suspect candidates can be prioritized based on their potential risk (i.e., hazard and exposure) by combining ionization efficiency-based concentration estimation, in vitro toxicity data or, if not available, structural alerts and QSAR.based toxicity predictions. The acquired information shows that NTS analyses have the potential to complement target analyses, allowing to update and adapt current monitoring programs, ultimately leading to improved monitoring of drinking water sources.
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36. |
- Bengtsson-Palme, Johan, 1985, et al.
(author)
-
Industrial wastewater treatment plant enriches antibiotic resistance genes and alters the structure of microbial communities
- 2019
-
In: Water Research. - : Elsevier BV. - 0043-1354 .- 1879-2448. ; 162, s. 437-445
-
Journal article (peer-reviewed)abstract
- Antibiotic resistance is an emerging global health crisis, driven largely by overuse and misuse of antibiotics. However, there are examples in which the production of these antimicrobial agents has polluted the environment with active antibiotic residues, selecting for antibiotic resistant bacteria and the genes they carry. In this work, we have used shotgun metagenomics to investigate the taxonomic structure and resistance gene composition of sludge communities in a treatment plant in Croatia receiving wastewater from production of the macrolide antibiotic azithromycin. We found that the total abundance of antibiotic resistance genes was three times higher in sludge from the treatment plant receiving wastewater from pharmaceutical production than in municipal sludge from a sewage treatment plant in Zagreb. Surprisingly, macrolide resistance genes did not have higher abundances in the industrial sludge, but genes associated with mobile genetic elements such as integrons had. We conclude that at high concentrations of antibiotics, selection may favor taxonomic shifts towards intrinsically resistant species or strains harboring chromosomal resistance mutations rather than acquisition of mobile resistance determinants. Our results underscore the need for regulatory action also within Europe to avoid release of antibiotics into the environment.
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37. |
- Bergion, Viktor, 1986, et al.
(author)
-
Risk-based cost-benefit analysis for evaluating microbial risk mitigation in a drinking water system
- 2018
-
In: Water Research. - : Elsevier BV. - 0043-1354 .- 1879-2448. ; 132, s. 111-123
-
Journal article (peer-reviewed)abstract
- Waterborne outbreaks of gastrointestinal diseases can cause large costs to society. Risk management needs to be holistic and transparent in order to reduce these risks in an effective manner. Microbial risk mitigation measures in a drinking water system were investigated using a novel approach combining probabilistic risk assessment and cost-benefit analysis. Lake Vomb in Sweden was used to exemplify and illustrate the risk-based decision model. Four mitigation alternatives were compared, where the first three alternatives, A1-A3, represented connecting 25, 50 and 75%, respectively, of on-site wastewater treatment systems in the catchment to the municipal wastewater treatment plant. The fourth alternative, A4, represented installing a UV-disinfection unit in the drinking water treatment plant. Quantitative microbial risk assessment was used to estimate the positive health effects in terms of quality adjusted life years (QALYs), resulting from the four mitigation alternatives. The health benefits were monetised using a unit cost per QALY. For each mitigation alternative, the net present value of health and environmental benefits and investment, maintenance and running costs was calculated. The results showed that only A4 can reduce the risk (probability of infection) below the World Health Organization guidelines of 10−4 infections per person per year (looking at the 95th percentile). Furthermore, all alternatives resulted in a negative net present value. However, the net present value would be positive (looking at the 50th percentile using a 1% discount rate) if non-monetised benefits (e.g. increased property value divided evenly over the studied time horizon and reduced microbial risks posed to animals), estimated at 800–1200 SEK (€100–150) per connected on-site wastewater treatment system per year, were included. This risk-based decision model creates a robust and transparent decision support tool. It is flexible enough to be tailored and applied to local settings of drinking water systems. The model provides a clear and holistic structure for decisions related to microbial risk mitigation. To improve the decision model, we suggest to further develop the valuation and monetisation of health effects and to refine the propagation of uncertainties and variabilities between the included methods.
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38. |
- Betsholtz, Alexander, et al.
(author)
-
Ozonation of 14C-labeled micropollutants – mineralization of labeled moieties and adsorption of transformation products to activated carbon
- 2022
-
In: Water Research. - : Elsevier BV. - 0043-1354 .- 1879-2448. ; 221
-
Journal article (peer-reviewed)abstract
- Ozonation transformation products (OTPs) are largely unknown compounds that are formed during the ozonation of micropollutants, and it is uncertain to which extent these compounds can be removed by subsequent adsorption to activated carbon. Thus, 14C-labeled micropollutants were ozonated to generate 14C-labeled OTPs, for which the adsorption of the sum of all 14C-labeled OTPs to activated carbon could be determined, based on the adsorption of the labeled carbon. Further, 14CO2 traps were used to examine the mineralization of 14C-labeled moieties during ozonation. 14CO2-formation revealed a partial mineralization of the 14C-labeled moieties in all compounds except for propyl-labeled bisphenol A and O-methyl-labeled naproxen. A similar degree of mineralization was noted for different compounds labeled at the same moiety, including the carboxylic carbon in diclofenac and ibuprofen (∼40% at 1 g O3/g DOC) and the aniline ring in sulfamethoxazole and sulfadiazine (∼30% at 1 g O3/g DOC). Aromatic ring cleavage was also confirmed for bisphenol A, sulfamethoxazole, and sulfadiazine through the formation of 14CO2. The adsorption experiments demonstrated increased adsorption of micropollutants to powdered activated carbon after ozonation, which was connected to a decreased adsorption of dissolved organic matter (DOM). Conversely, the OTPs showed a substantial and successive decline in adsorption at increased ozone doses for all compounds, likely due to decreased hydrophobicity and aromaticity of the OTPs. These findings indicate that adsorption to activated carbon alone is not a viable removal method for a wide range of ozonation transformation products.
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39. |
- Bighiu, Maria, et al.
(author)
-
Limited effects of pesticides on stream macroinvertebrates, biofilm nematodes, and algae in intensive agricultural landscapes in Sweden
- 2020
-
In: Water Research. - : Elsevier BV. - 0043-1354 .- 1879-2448. ; 174
-
Journal article (peer-reviewed)abstract
- Pesticides are frequently detected in surface waters, sometimes at levels exceeding ecotoxicological guidelines. We screened for almost 100 pesticides in 32 streams from intense agricultural areas in Southern Sweden, in concert with water chemistry parameters. In addition, we investigated the communities of benthic macroinvertebrates, biofilm nematodes and algae and calculated multiple bioassessment metrics. The number of pesticides found in each stream ranged between 2 and 52, but the sum of Toxic Units (Sigma TU) for the mixtures was generally low, and exceeded the European Uniform Principles only in a single sample for algae and in 2% of the samples for Daphnia. Only nematode communities were significantly correlated with the Sigma TU, potentially due to their higher pesticide exposure in biofilms. Diatom metrics showed that most streams were impacted by eutrophication and macroinvertebrate metrics showed good status in most streams, whereas the SPEAR(pesticides) (SPEcies At Risk) index, specifically designed to indicate pesticide effects, showed that about half of the samples were at risk. Interestingly, SPEAR(pesticides) was not correlated to Sigma TUDaphnia and this discrepancy suggests that redefining the boundaries for quality classes might be necessary for this index. Moreover, SPEAR(pesticides) was positively correlated with the commonly used macroinvertebrate index ASPT, although disparate results were found for several streams. We argue that this questions the scaling of both metrics and the specificity of their responses. We discuss that the overall good/moderate status of the streams, despite the intense agriculture in the catchments, can be due to the fact that i) a sampling strategy with repeated grab samples did not capture peak pesticide concentrations, thus underestimating acute exposure, ii) pesticide run-off indeed was low, due to measures such as buffer strips, and iii) the nutrient-rich conditions and high sediment loads counteracted pesticide toxicity. We conclude that agricultural land use was the overriding stressor in the investigated streams, including strong effects of nutrients, less apparent effects of pesticides and likely impact of hydromorphological alterations (not specifically addressed in this study). (C) 2020 The Authors. Published by Elsevier Ltd.
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40. |
- Bijmans, Martijn FM, et al.
(author)
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Selective recovery of nickel over iron from a nickel-iron solution using microbial sulfate reduction in a gas-lift bioreactor
- 2009
-
In: Water Research. - : IWA Publishing. - 0043-1354 .- 1879-2448. ; 43:3, s. 853-861
-
Journal article (peer-reviewed)abstract
- Process streams with high concentrations of metals and sulfate are characteristic for the mining and metallurgical industries. This study aims to selectively recover nickel from a nickel-iron-containing solution at pH 5.0 using a single stage bioreactor that simultaneously combines low pH sulfate reduction and metal-sulfide formation. The results show that nickel was selectively precipitated in the bioreactor at pH 5.0 and the precipitates consisted of >= 83% of the nickel content. The nickel-iron precipitates were partly crystalline and had a metal/sulfur ratio of 1, suggesting these precipitates were NiS and FeS. Experiments focusing on nickel recovery at pH 5.0 and 5.5 reached a recovery of >99.9%, resulting in a nickel effluent concentration <0.05 mu M. The mixed microbial population included known sulfate reducers and acetogens. This study shows that selective metal precipitation in a single stage sulfate reducing bioreactor operated at low pH has the potential to produce metal-sulfides that can be used by the metallurgical industry as a resource for metal production.
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41. |
- Biswas, Ashis, et al.
(author)
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Role of competing ions in the mobilization of arsenic in groundwater of Bengal Basin : Insight from surface complexation modeling
- 2014
-
In: Water Research. - : Elsevier. - 0043-1354 .- 1879-2448. ; 55, s. 30-39
-
Journal article (peer-reviewed)abstract
- This study assesses the role of competing ions in the mobilization of arsenic (As) by surface complexation modeling of the temporal variability of As in groundwater. The potential use of two different surface complexation models (SCMs), developed for ferrihydrite and goethite, has been explored to account for the temporal variation of As(III) and As(V) concentration, monitored in shallow groundwater of Bengal Basin over a period of 20 months. The SCM for ferrihydrite appears as the better predictor of the observed variation in both As(III) and As(V) concentrations in the study sites. It is estimated that among the competing ions, PO43- is the major competitor of As(III) and As(V) adsorption onto Fe oxyhydroxide, and the competition ability decreases in the order PO43- >> Fe(II) > H4SiO4 = HCO- (3.) It is further revealed that a small change in pH can also have a significant effect on the mobility of As(III) and As(V) in the aquifers. A decrease in pH increases the concentration of As(III), whereas it decreases the As(V) concentration and vice versa. The present study suggests that the reductive dissolution of Fe oxyhydroxide alone cannot explain the observed high As concentration in groundwater of the Bengal Basin. This study supports the view that the reductive dissolution of Fe oxyhydroxide followed by competitive sorption reactions with the aquifer sediment is the processes responsible for As enrichment in groundwater.
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42. |
- Blecken, Godecke-Tobias, et al.
(author)
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Influence of intermittent wetting and drying conditions on heavy metal removal by stormwater biofilters
- 2009
-
In: Water Research. - : Elsevier BV. - 0043-1354 .- 1879-2448. ; 43:18, s. 4590-4598
-
Journal article (peer-reviewed)abstract
- Biofiltration is a technology to treat urban stormwater runoff which conveys pollutants, including heavy metals. However, the variability of metals removal performance in biofiltration systems is as yet unknown.A laboratory study has been conducted with vegetated biofilter mesocosms, partly fitted with a submerged zone at the bottom of the filter combined with a carbon source. The biofilters were dosed with stormwater according to three different dry/wet schemes, to investigate the effect of intermittent wetting and drying conditions on metal removal.Provided that the biofilters received regular stormwater input, metal removal exceeded 95%. The highest metal accumulation occurs in the top layer of the filter media.However, after antecedent drying before a storm event exceeding three to four weeks the filters performed significantly worse, although metal removal still remained relatively high. Introducing a submerged zone into the filter improved the performance significantly after extended dry periods. In particular, copper removal in filters equipped with a submerged zone was increased by around 12% (α = 0.05) both during wet and dry periods and for lead the negative effect of drying could completely be eliminated, with consistently low outflow concentrations even after long drying periods.
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43. |
- Bohus, Veronika, et al.
(author)
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Microbiological investigation of an industrial ultra pure supply water plant using cultivation-based and cultivation-independent methods
- 2010
-
In: Water Research. - : Elsevier BV. - 0043-1354 .- 1879-2448. ; 44:20, s. 6124-6132
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Journal article (peer-reviewed)abstract
- Ultra pure waters (UPW), characterized by extremely low salt and nutrient concentrations, can suffer from microbial contamination which causes biofouling and biocorrosion, possibly leading to reduced lifetime and increased operational costs. Samples were taken from an ultra pure supply water producing plant of a power plant. Scanning electron microscopic examination was carried out on the biofilms formed in the system. Biofilm, ion exchange resin, and water samples were characterized by culture-based methods and molecular fingerprinting (terminal restriction fragment length polymorphism [T-RFLP] analysis and molecular cloning). Identification of bacteria was based on 16S rDNA sequence comparison. A complex microbial community structure was revealed. Nearly 46% of the clones were related to as yet uncultured bacteria. The community profiles of the water samples were the most diverse and most of bacteria were recruited from bacterial communities of tube surface and ion exchange resin biofilms. Microbiota of different layers of the mixed bed ion exchange resin showed the highest similarity. Most of the identified taxa (dominated by β-Proteobacteria) could take part in microbially influenced corrosion. © 2010 Elsevier Ltd.
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44. |
- Bonaglia, Stefano, et al.
(author)
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Capping with activated carbon reduces nutrient fluxes, denitrification and meiofauna in contaminated sediments
- 2019
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In: Water Research. - : Elsevier BV. - 0043-1354 .- 1879-2448. ; 148, s. 515-525
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Journal article (peer-reviewed)abstract
- Sediment capping with activated carbon (AC) is an effective technique used in remediation of contaminated sediments, but the ecological effects on benthic microbial activity and meiofauna communities have been largely neglected. This study presents results from a 4-week experiment investigating the influence of two powdered AC materials (bituminous coal-based and coconut shell-derived) and one control material (clay) on biogeochemical processes and meiofauna in contaminated sediments. Capping with AC induced a 62‒63% decrease in denitrification and a 66‒87 % decrease in dissimilatory nitrate reduction to ammonium (DNRA). Sediment porewater pH increased from 7.1 to 9.0 and 9.7 after addition of bituminous AC and biomass-derived AC, respectively. High pH (>8) persisted for at least two weeks in the bituminous AC and for at least 24 days in the coconut based AC, while capping with clay had no effect on pH. We observed a strong impact (nitrate fluxes being halved in presence of AC) on nitrification activity as nitrifiers are sensitive to high pH. This partly explains the significant decrease in nitrate reduction rates since denitrification was almost entirely coupled to nitrification. Total benthic metabolism estimated by sediment oxygen uptake was reduced by 30 and 43 % in presence of bituminous coal-based AC and coconut shell-derived AC, respectively. Meiofauna abundances decreased by 60‒62 % in the AC treatments. Taken together, these observations suggest that AC amendments deplete natural organic carbon, intended as food, to heterotrophic benthic communities. Phosphate efflux was 91 % lower in presence of bituminous AC compared to untreated sediment probably due to its content of aluminum (Al) oxides, which have high affinity for phosphate. This study demonstrates that capping with powdered AC produces significant effects on benthic biogeochemical fluxes, microbial processes and meiofauna abundances, which are likely due to an increase in porewater pH and to the sequestration of natural, sedimentary organic matter by AC particles.
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45. |
- Boström, Marja L., et al.
(author)
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Influence of pH-dependent aquatic toxicity of ionizable pharmaceuticals on risk assessments over environmental pH ranges.
- 2015
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In: Water Research. - : Elsevier BV. - 1879-2448 .- 0043-1354. ; 72:Online 6 September 2014, s. 154-161
-
Journal article (peer-reviewed)abstract
- Due to variation in pH, ionizable pharmaceuticals entering aquatic environments experience different degrees of ionization, which may affect toxicity. Using data from toxicity testing at only neutral pH may potentially under- or overestimate actual toxicity at pH ranges found in natural aquatic environments. Here we show relative pH-dependent acute toxicity to Daphnia magna for the pharmaceutical weak bases fluoxetine and sertraline, as well as the weak acids naproxen, diclofenac, ibuprofen and ketoprofen. A probabilistic modelling approach using the pH-dependent toxicity data for D. magna and an environmental pH distribution based on over 4000 European running waters from 21 countries predicted that environmental toxicity for the weak bases may be underestimated if pH 7 was assumed. The model predicted median underestimation by a factor of 3, with 90% of the model results ranging from 1 to 6. Consequently, due to the slightly basic nature of the European running waters, weak acid toxicity may be overestimated by a factor of 2. Predicted median toxicity was 0.5 of that assuming pH 7 with 90% of the results ranging from 0.03 to 5. Because aquatic pH exhibits large variation both within and between countries, we advise the use of site-specific risk assessments for ionizable pharmaceuticals in making informed water management decisions.
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46. |
- Bravo, Andrea Garcia, et al.
(author)
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High methylmercury production under ferruginous conditions in sediments impacted by sewage treatment plant discharges
- 2015
-
In: Water Research. - : Elsevier BV. - 0043-1354 .- 1879-2448. ; 80, s. 245-255
-
Journal article (peer-reviewed)abstract
- Sewage treatment plants (STPs) are important point sources of mercury (Hg) to the environment. STPs are also significant sources of iron when hydrated ferric oxide (HFO) is used as a dephosphatation agent during water purification. In this study, we combined geochemical and microbiological characterization with Hg speciation and sediment amendments to evaluate the impact of STP's effluents on monomethylmercury (MMHg) production. The highest in-situ Hg methylation was found close to the discharge pipe in subsurface sediments enriched with Hg, organic matter, and iron. There, ferruginous conditions were prevailing with high concentrations of dissolved Fe2+ and virtually no free sulfide in the porewater. Sediment incubations demonstrated that the high MMHg production close to the discharge was controlled by low demethylation yields. Inhibition of dissimilatory sulfate reduction with molybdate led to increased iron reduction rates and Hg-methylation, suggesting that sulfate-reducing bacteria (SRB) may not have been the main Hg methylators under these conditions. However, Hg methylation in sediments amended with amorphous Fe(III)-oxides was only slightly higher than control conditions. Thus, in addition to iron-reducing bacteria, other non-SRB most likely contributed to Hg methylation. Overall, this study highlights that sediments impacted by STP discharges can become local hot-spots for Hg methylation due to the combined inputs of i) Hg, ii) organic matter, which fuels bacterial activities and iii) iron, which keeps porewater sulfide concentration low and hence Hg bioavailable.
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47. |
- Bravo, Andrea G., et al.
(author)
-
The interplay between total mercury, methylmercury and dissolved organic matter in fluvial systems : A latitudinal study across Europe
- 2018
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In: Water Research. - : Elsevier. - 0043-1354 .- 1879-2448. ; 144, s. 172-182
-
Journal article (peer-reviewed)abstract
- Large-scale studies are needed to identify the drivers of total mercury (THg) and monomethyl-mercury (MeHg) concentrations in aquatic ecosystems. Studies attempting to link dissolved organic matter (DOM) to levels of THg or MeHg are few and geographically constrained. Additionally, stream and river systems have been understudied as compared to lakes. Hence, the aim of this study was to examine the influence of DOM concentration and composition, morphological descriptors, land uses and water chemistry on THg and MeHg concentrations and the percentage of THg as MeHg (%MeHg) in 29 streams across Europe spanning from 41°N to 64°N. THg concentrations (0.06–2.78 ng L−1) were highest in streams characterized by DOM with a high terrestrial soil signature and low nutrient content. MeHg concentrations (7.8–159 pg L−1) varied non-systematically across systems. Relationships between DOM bulk characteristics and THg and MeHg suggest that while soil derived DOM inputs control THg concentrations, autochthonous DOM (aquatically produced) and the availability of electron acceptors for Hg methylating microorganisms (e.g. sulfate) drive %MeHg and potentially MeHg concentration. Overall, these results highlight the large spatial variability in THg and MeHg concentrations at the European scale, and underscore the importance of DOM composition on mercury cycling in fluvial systems.
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48. |
- Bravo, Andrea G., et al.
(author)
-
The interplay between total mercury, methylmercury and dissolved organic matter in fluvial systems : A latitudinal study across Europe
- 2018
-
In: Water Research. - : Pergamon. - 0043-1354 .- 1879-2448. ; 144, s. 172-182
-
Journal article (peer-reviewed)abstract
- Large-scale studies are needed to identify the drivers of total mercury (THg) and monomethyl-mercury (MeHg) concentrations in aquatic ecosystems. Studies attempting to link dissolved organic matter (DOM) to levels of THg or MeHg are few and geographically constrained. Additionally, stream and river systems have been understudied as compared to lakes. Hence, the aim of this study was to examine the influence of DOM concentration and composition, morphological descriptors, land uses and water chemistry on THg and MeHg concentrations and the percentage of THg as MeHg (%MeHg) in 29 streams across Europe spanning from 41°N to 64 °N. THg concentrations (0.06–2.78 ng L−1) were highest in streams characterized by DOM with a high terrestrial soil signature and low nutrient content. MeHg concentrations (7.8–159 pg L−1) varied non-systematically across systems. Relationships between DOM bulk characteristics and THg and MeHg suggest that while soil derived DOM inputs control THg concentrations, autochthonous DOM (aquatically produced) and the availability of electron acceptors for Hg methylating microorganisms (e.g. sulfate) drive %MeHg and potentially MeHg concentration. Overall, these results highlight the large spatial variability in THg and MeHg concentrations at the European scale, and underscore the importance of DOM composition on mercury cycling in fluvial systems.
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49. |
- Broman, Elias, et al.
(author)
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Active DNRA and denitrification in oxic hypereutrophic waters
- 2021
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In: Water Research. - : Elsevier BV. - 0043-1354 .- 1879-2448. ; 194
-
Journal article (peer-reviewed)abstract
- Since the start of synthetic fertilizer production more than a hundred years ago, the coastal ocean has been exposed to increasing nutrient loading, which has led to eutrophication and extensive algal blooms. Such hypereutrophic waters might harbor anaerobic nitrogen (N) cycling processes due to low-oxygen mi- croniches associated with abundant organic particles, but studies on nitrate reduction in coastal pelagic environments are scarce. Here, we report on 15 N isotope-labeling experiments, metagenome, and RT-qPCR data from a large hypereutrophic lagoon indicating that dissimilatory nitrate reduction to ammonium (DNRA) and denitrification were active processes, even though the bulk water was fully oxygenated ( > 224 μM O 2 ). DNRA in the bottom water corresponded to 83% of whole-ecosystem DNRA (water + sedi- ment), while denitrification was predominant in the sediment. Microbial taxa important for DNRA accord- ing to the metagenomic data were dominated by Bacteroidetes (genus Parabacteroides ) and Proteobac- teria (genus Wolinella ), while denitrification was mainly associated with proteobacterial genera Pseu- domonas, Achromobacter , and Brucella . The metagenomic and microscopy data suggest that these anaero- bic processes were likely occurring in low-oxygen microniches related to extensive growth of filamentous cyanobacteria, including diazotrophic Dolichospermum and non-diazotrophic Planktothrix . By summing the total nitrate fluxes through DNRA and denitrification, it results that DNRA retains approximately one fifth (19%) of the fixed N that goes through the nitrate pool. This is noteworthy as DNRA represents thus a very important recycling mechanism for fixed N, which sustains algal proliferation and leads to further enhancement of eutrophication in these endangered ecosystems.
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50. |
- Bundschuh, Jochen, et al.
(author)
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Emerging mitigation needs and sustainable options for solving the arsenic problems of rural and isolated urban areas in Latin America : A critical analysis
- 2010
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In: Water Research. - : Elsevier BV. - 0043-1354 .- 1879-2448. ; 44:19, s. 5828-5845
-
Journal article (peer-reviewed)abstract
- In this work, current information about the contamination of ground- and surface-water resources by arsenic from geogenic sources in Latin America is presented together with possible emerging mitigation solutions. The problem is of the same order of magnitude as other world regions, such as SE Asia, but it is often not described in English. Despite the studies undertaken by numerous local researchers, and the identification of proven treatment methods for the specific water conditions encountered, no technologies have been commercialized due to a current lack of funding and technical assistance. Emerging, low-cost technologies to mitigate the problem of arsenic in drinking water resources that are suitable for rural and urban areas lacking centralized water supplies have been evaluated. The technologies generally use simple and low-cost equipment that can easily be handled and maintained by the local population. Experiences comprise (i) coagulation/filtration with iron and aluminum salts, scaled-down for small community-and household-scale-applications, (ii) adsorption techniques using low-cost arsenic sorbents, such as geological materials (clays, laterites, soils, limestones), natural organic-based sorbents (natural biomass), and synthetic materials. TiO2-heterogeneous photocatalysis and zerovalent iron, especially using nanoscale particles, appear to be promising emergent technologies. Another promising innovative method for rural communities is the use of constructed wetlands using native perennial plants for arsenic rhizofiltration. Smallscale simple reverse osmosis equipment (which can be powered by wind or solar energy) that is suitable for small communities can also be utilized. The individual benefits of the different methods have been evaluated in terms of (i) size of the treatment device, (ii) arsenic concentration and distribution of species, chemical composition and grade of mineralization in the raw water, (iii) guidelines for the remaining As concentration, (iv) economical constrains, (v) complexity of installation and maintenance, and infrastructure constraints (e.g. electricity needs). (c) 2010 Elsevier Ltd. All rights reserved.
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