| 1. |
- Andersson, Anna, et al.
(författare)
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Selective removal of natural organic matter during drinking water production changes the composition of disinfection by-products
- 2020
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Ingår i: Environmental Science. - : ROYAL SOC CHEMISTRY. - 2053-1400 .- 2053-1419. ; 6:3, s. 779-794
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Tidskriftsartikel (refereegranskat)abstract
- Disinfection by-products (DBPs) are potentially toxic compounds formed upon chemical disinfection of drinking water. Controlling the levels and characteristics of dissolved organic matter (DOM) as precursor material for DBPs is a major target to reduce DBP formation. A pilot-scale treatment including suspended ion exchange (SIX (R)), a ceramic microfilter (CeraMac (R)) with in-line coagulation and optional pre-ozonation followed by granular activated carbon (GAC) filtration was compared with a conventional full-scale treatment based on DOM removal and DBP formation using Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS), rapid fractionation, liquid chromatography organic carbon detection (LC-OCD), adsorbable organic halogens (AOX) and trihalomethane (THM) analysis. The new treatment combination showed different selectivity for DOM removal, compared to the conventional, leading to changes in composition of the DBPs formed. SIX (R) and GAC had the largest impacts on reducing AOX and THM formation potentials but the high adsorptive capacity of GAC affected the diversity of detected DBPs most. Chlorination and chloramination of pilot treated water with doses normally used in Sweden produced low levels of AOX compared to the full-scale treatment, but FT-ICR MS revealed an abundance of brominated DBP species in contrast with the conventional treatment, which were dominated by chlorinated DBPs. This finding was largely linked to the high DOM removal by the pilot treatment, causing an increased Br-/C ratio and a higher formation of HOBr. Potential increases in Br-DBPs are important to consider in minimizing health risks associated with DBPs, because of the supposed higher toxicity of Br-DBPs compared to Cl-DBPs.
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| 2. |
- Andersson, Anna, et al.
(författare)
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Waterworks-specific composition of drinking water disinfection by-products
- 2019
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Ingår i: Environmental Science. - Cambridge : Royal Society of Chemistry. - 2053-1400 .- 2053-1419. ; :5, s. 861-872
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Tidskriftsartikel (refereegranskat)abstract
- Reactions between chemical disinfectants and natural organic matter (NOM) upon drinking water treatment result in formation of potentially harmful disinfection by-products (DBPs). The diversity of DBPs formed is high and a large portion remains unknown. Previous studies have shown that non-volatile DBPs are important, as much of the total toxicity from DBPs has been related to this fraction. To further understand the composition and variation of DBPs associated with this fraction, non-target analysis with ultrahigh resolution Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) was employed to detect DBPs at four Swedish waterworks using different types of raw water and treatments. Samples were collected five times covering a full year. A common group of DBPs formed at all four waterworks was detected, suggesting a similar pool of DBP precursors in all raw waters that might be related to phenolic moieties. However, the largest proportion (64–92%) of the assigned chlorinated and brominated molecular formulae were unique, i.e. were solely found in one of the four waterworks. In contrast, the compositional variations of NOM in the raw waters and samples collected prior to chemical disinfection were rather limited.This indicated that waterworks-specific DBPs presumably originated from matrix effects at the point of disinfection, primarily explained by differences in bromide levels, disinfectants (chlorine versus chloramine) and different relative abundances of isomers among the NOM compositions studied. The large variation of observed DBPs in the toxicologically relevant non-volatile fraction indicates that non-targeted monitoring strategies might be valuable to ensure relevant DBP monitoring in the future.
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| 3. |
- Köhler, Stephan, et al.
(författare)
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Upgrading coagulation with hollow-fibre nanofiltration for improved organic matter removal during surface water treatment.
- 2016
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Ingår i: Water Research. - : Elsevier BV. - 1879-2448 .- 0043-1354. ; 89, s. 232-240
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Tidskriftsartikel (refereegranskat)abstract
- Rising organic matter concentrations in surface waters in many Nordic countries require current drinking water treatment processes to be adapted. Accordingly, the use of a novel nanofiltration (NF) membrane was studied during a nine month period in pilot scale at a large drinking water treatment plant in Stockholm, Sweden. A chemically resistant hollow-fibre NF membrane was fed with full scale process water from a rapid sand filter after aluminum sulfate coagulation. The combined coagulation and NF process removed more than 90% of the incoming lake water dissolved organic carbon (DOC) (8.7 mg C L(-1)), and 96% of the absorbance at 254 nm (A254) (0.28 cm(-1) incoming absorbance). Including granulated active carbon GAC) filter, the complete pilot plant treatment process we observed decreases in DOC concentration (8.7-0.5 mg C L(-1)), SUVA (3.1-1.7 mg(-1) L m(-1)), and the average nominal molecular mass (670-440 Da). Meanwhile, water hardness was practically unaffected (<20% reduction). Humic substances (HS) and biopolymers were almost completely eliminated (6510-140 and 260 to 10 μg C L(-1) respectively) and low molecular weight (LMW) neutrals decreased substantially (880-190 μg C L(-1)). Differential excitation emission matrices (EEMs), which illustrate the removal of fluorescing organic matter (FDOM) over a range of excitation and emission wavelengths, demonstrate that coagulation removed 35 ± 2% of protein-like material and 65 ± 2% of longer emission wavelength, humic-like FDOM. The subsequent NF treatment was somewhat less selective but still preferentially targeted humic-like FDOM (83 ± 1%) to a larger extent than protein-like material (66 ± 3%). The high selectivity of organic matter during coagulation compared to NF separation was confirmed from analyses with Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS), and liquid chromatography with organic carbon detection (LC-OCD), as coagulation exclusively targeted oxidized organic matter components while NF removed both chemically reduced and oxidized components. DOC removal and change in DOC character in the GAC filters showed marked differences with slower saturation and more pronounced shifts in DOC character using NF as pre-treatment. Fluorescence derived parameters showed a similar decrease over time of GAC performance for the first 150 days but also indicated ongoing change of DOM character in the post NF GAC filtrate over time even after LC-OCD indicated steady state with respect to outgoing carbon. During our trial iron concentrations were low (<30 ppb) and thus A254 could be directly related to the concentration of HS (R(2) = 0.9). The fluorescence derived freshness index (β:α) proved to be an excellent variable for estimating the fraction of HS present in all samples. Given the recommended limit of 4 mg L(-1) for chemical oxygen demand (COD) for Swedish drinking water, coagulation will need to be supplemented with one or more treatment steps irrespective whether climate change will lead to drier or wetter conditions in order to maintain sufficient DOC removal with the current increasing concentrations in raw waters.
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| 4. |
- Lavonen, Elin, et al.
(författare)
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Selective Chlorination of Natural Organic Matter: Identification of Previously Unknown Disinfection Byproducts
- 2013
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Ingår i: Environmental Science and Technology. - : American Chemical Society. - 0013-936X .- 1520-5851. ; 47:5, s. 2264-2271
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Tidskriftsartikel (refereegranskat)abstract
- Natural organic matter (NOM) serve as precursors for disinfection byproducts (DBPs) in drinking water production making NOM removal essential in predisinfection treatment processes. We identified molecular formulas of chlorinated DBPs after chlorination and chloramination in four Swedish surface water treatment plants (WTPs) using ultrahigh resolution Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS). Chlorine-containing formulas were detected before and after disinfection and were therefore classified to identify DBPs. In total, 499 DBPs were detected, of which 230 have not been reported earlier. The byproducts had, as a group, significantly lower ratio of hydrogen to carbon (H/C) and significantly higher average carbon oxidation state (Cos), double bond equivalents per carbon (DBE/C) and ratio of oxygen to carbon (O/C) compared to Cl-containing components present before disinfection and CHO formulas in samples taken both before and after disinfection. Electrophilic substitution, the proposed most significant reaction pathway for chlorination of NOM, results in carbon oxidation and decreased H/C while O/C and DBE/C is left unchanged. Because the identified DBPs had significantly higher DBE/C and O/C than the CHO formulas we concluded that chlorination of NOM during disinfection is selective toward components with relatively high double bond equivalency and number of oxygen atoms per carbon. Furthermore, choice of disinfectant, dose, and predisinfection treatment at the different WTPs resulted in distinct patterns in the occurrence of DBP formulas.
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| 5. |
- Lavonen, Elin
(författare)
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Tracking changes in dissolved natural organic matter composition : evaluating drinking water production using optical and molecular level tools
- 2015
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- During the last decades, the abundance of dissolved organic matter (DOM), a complex heterogeneous mixture of organic compounds, has increased in many surface waters in Northern Europe and North America. Surface waters are widely used as raw water sources for drinking water production. Increasing DOM is problematic for water treatment plants (WTPs) due to e.g. increased coagulant demand and because its constituents act as precursors for potentially harmful disinfection by-products. Many WTPs employing conventional treatment are currently struggling to maintain sufficient DOM removal, and are considering additional novel techniques. In this thesis, changes in the DOM composition were investigated during i) conventional water treatment and disinfection practices, ii) pilot scale studies of novel processes (nanofiltration and ion exchange), and iii) transport in a large Swedish boreal lake. Analytical techniques used include common spectroscopic methods (absorbance and fluorescence), and more advanced molecular level techniques (ultra-high resolution mass spectrometry). Results show that coagulation was highly selective towards oxidized DOM components, and that the removed fraction resembled terrestrial endmembers. Meanwhile, DOM with microbial endmember characteristics, which correlated with chemically reduced DOM components, was especially reactive during slow sand filtration. After disinfection, 499 different chlorine-containing by-products were identified, of which many had not been reported in the literature earlier. Both nanofiltration and ion exchange removed more DOM than coagulation, and components with a wider range of chemical properties. Both techniques were, however, most efficiently removing terrestrial DOM. In the studied large boreal lake, terrestrial, aromatic compounds were lost over time, while no significant net in-lake production occurred. Decreasing components overlapped largely with those removed during coagulation treatment at WTPs, indicating that coagulation had contributed significantly to DOM removal within the lake, especially considering a concurrent loss of dissolved iron.
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| 6. |
- Lavonen, Elin, et al.
(författare)
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Tracking changes in the optical properties and molecular composition of dissolved organic matter during drinking water production
- 2015
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Ingår i: Water Research. - : Elsevier BV. - 0043-1354 .- 1879-2448. ; 85, s. 286-294
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Tidskriftsartikel (refereegranskat)abstract
- Absorbance, 3D fluorescence and ultrahigh resolution electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI-FT-ICR-MS) were used to explain patterns in the removal of chromophoric and fluorescent dissolved organic matter (CDOM and FDOM) at the molecular level during drinking water production at four large drinking water treatment plants in Sweden. When dissolved organic carbon (DOC) removal was low, shifts in the dissolved organic matter (DOM) composition could not be detected with commonly used DOG-normalized parameters (e.g. specific UV254 absorbance SUVA), but was clearly observed by using differential absorbance and fluorescence or ESI-FT-ICR-MS. In addition, we took a novel approach by identifying how optical parameters were correlated to the elemental composition of DOM by using rank correlation to connect optical properties to chemical formulas assigned to mass peaks from FT-ICR-MS analyses. Coagulation treatment selectively removed FDOM at longer emission wavelengths (450-600 nm), which significantly correlated with chemical formulas containing oxidized carbon (average carbon oxidation state >= 0), low hydrogen to carbon ratios (H/C: average +/- SD = 0.83 +/- 0.13), and abundant oxygen-containing functional groups (O/C = 0.62 +/- 0.10). Slow sand filtration was less efficient in removing DOM, yet selectively targeted FDOM at shorter emission wavelengths (between 300 and 450 nm), which commonly represents algal rather than terrestrial sources. This shorter wavelength FDOM correlated with chemical formulas containing reduced carbon (average carbon oxidation state <= 0), with relatively few carbon-carbon double bonds (H/C = 1.32 +/- 0.16) and less oxygen per carbon (O/C = 0.43 +/- 0.10) than those removed during coagulation. By coupling optical approaches with FT-ICR-MS to characterize DOM, we were for the first time able to confirm the molecular composition of absorbing and fluorescing DOM selectively targeted during drinking water treatment.
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| 7. |
- Lidén, Angelica, et al.
(författare)
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Integrity breaches in a hollow fiber nanofilter – Effects on natural organic matter and virus-like particle removal
- 2016
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Ingår i: Water Research. - : Elsevier BV. - 0043-1354 .- 1879-2448. ; 105, s. 231-240
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Tidskriftsartikel (refereegranskat)abstract
- Ultrafiltration and nanofiltration have become common methods to treat surface water for drinking water purposes. Common aims of a membrane step are removal of natural organic matter (NOM), softening or adding an extra microbiological or chemical barrier. In most cases, the membrane is considered a good disinfection step; commonly the viral removal is at least 4–log. To ensure a working disinfection, reliable integrity tests are required. In the present pilot study with a hollow fiber nanofilter, the membrane achieved a high NOM reduction, and the difference in parameters related to NOM quality before and after treatment proved to be useful indicators of integrity breaches. Changes in total organic carbon (TOC) concentration, UV-absorbance at 254 nm (UVA254) and fluorescence derived parameters in the permeate flow were related to leaking fibers. On average, UVA254 in the permeate was 3 times higher for a membrane with compromised fibers (0.041 cm−1) compared to an intact membrane (0.013 cm−1), while TOC was less than 2 times as high on average. Thus, this membrane had a higher reduction of UVA254 than TOC and the sensitivity for changes from leakage was higher. Therefore, it is suggested that UVA254 could be used as an indicator for membrane integrity. Additionally, there is a significant (P < 0.01) difference in fluorescence derived parameters between a leaking and an intact fiber, showing that fluorescence also has potential to be applied for online monitoring of membrane processes. During fiber failure, around 2% of the permeate flow passes through one single leaking fiber. The transport depends on the distance between the inflow and the leak, which in most cases are similar and most likely close to the middle of the fiber.
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| 8. |
- Lundqvist, Johan, et al.
(författare)
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Innovative drinking water treatment techniques reduce the disinfection-induced oxidative stress and genotoxic activity
- 2019
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Ingår i: Water Research. - : Elsevier. - 0043-1354 .- 1879-2448. ; 5, s. 182-192
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Tidskriftsartikel (refereegranskat)abstract
- Disinfection of drinking water using chlorine can lead to the formation of genotoxic by-products whenchlorine reacts with natural organic matter (NOM). A vast number of such disinfection by-products(DBPs) have been identified, making it almost impossible to routinely monitor all DBPs with chemicalanalysis. In this study, a bioanalytical approach was used, measuring oxidative stress (Nrf2 activity),genotoxicity (micronucleus test), and aryl hydrocarbon receptor (AhR) activation to evaluate an innovativewater treatment process, including suspended ion exchange, ozonation, in-line coagulation,ceramic microfiltration, and granular activated carbon. Chlorination was performed in laboratory scaleafter each step in the treatment process in order to investigate the effect of each treatment process to theformation of DBPs. Suspended ion exchange had a high capacity to remove dissolved organic carbon(DOC) and to decrease UV absorbance and Nrf2 activity in non-chlorinated water. High-dose chlorination(10 mg Cl2 L-1) of raw water caused a drastic induction of Nrf2 activity, which was decreased by 70% inwater chlorinated after suspended ion exchange. Further reduction of Nrf2 activity following chlorinationwas achieved by ozonation and the concomitant treatment steps. The ozonation treatment resulted indecreased Nrf2 activity in spite of unchanged DOC levels. However, a strong correlation was found betweenUV absorbing compounds and Nrf2 activity, demonstrating that Nrf2 inducing DBPs were formedfrom pre-cursors of a specific NOM fraction, constituted of mainly aromatic compounds. Moreover, highdosechlorination of raw water induced genotoxicity. In similarity to the DOC levels, UV absorbance andNrf2 activity, the disinfection-induced genotoxicity was also reduced by each treatment step of theinnovative water treatment technique. AhR activity was observed in the water produced by the conventionalprocess and in the raw water, but the activity was clearly decreased by the ozonation step inthe innovative water treatment process.
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| 9. |
- Ullberg, Malin, et al.
(författare)
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Pilot-scale removal of organic micropollutants and natural organic matter from drinking water using ozonation followed by granular activated carbon
- 2021
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Ingår i: Environmental Science: Water Research & Technology. - : Royal Society of Chemistry (RSC). - 2053-1400 .- 2053-1419. ; 7, s. 535-548
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Tidskriftsartikel (refereegranskat)abstract
- Conventional drinking water treatment is inefficient in removing a large fraction of known organic micropollutants (OMPs). Therefore more efficient treatment approaches are needed to limit exposure to OMPs via drinking water. Here, the OMP removal performance of a combination of ozonation/no ozonation and two types of granular activated carbon (GAC) was tested in a one-year pilot-scale study, alongside a study of full-scale treatment. The raw water was lake water with low ambient concentrations of OMPs. In total, 29 of 99 targeted OMPs (per- and polyfluoroalkyl substances (PFASs), pharmaceuticals and other OMPs) were detected (mean n-ary sumation OMPs = 57 +/- 16 ng L-1). Only a few OMPs were consistently removed in the full-scale process, while ozonation in the pilot experiment effectively removed 72% of detected compounds to levels <30%. The GAC columns showed breakthrough of OMPs and dissolved organic carbon (DOC) for both ozonated and non-ozonated water, with earlier breakthrough for DOC than OMPs. Breakthrough of OMPs was delayed in ozonated columns, possibly because of lower adsorption competition with low-molecular-weight natural organic matter (NOM) fractions measured with liquid chromatography (LC-OCD). The OMP removal performance of the two GAC materials was not affected by greater DOC loading, but Filtrasorb showed 25% higher removal of DOC without losing capacity to remove OMPs. Compounds with low log K-OC tended to break through earlier than those with higher K-OC values. The lowest levels of OMPs were observed in GAC effluents using ozonated feed water demonstrating the efficacy of combining ozone with GAC for managing OMP levels during drinking water production.
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