| 1. |
- Ahrens, Lutz
(författare)
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Exploring the adsorption of short and long chain per- and polyfluoroalkyl substances (PFAS) to different zeolites using environmental samples
- 2023
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Ingår i: Environmental Science: Water Research & Technology. - 2053-1400 .- 2053-1419.
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Tidskriftsartikel (refereegranskat)abstract
- Per- and polyfluoroalkyl substances (PFAS) are emerging contaminants that are gaining attention for their ubiquitous distribution, persistence, and toxicity in the environment and ecosystem. Among the PFAS removal techniques from water, adsorption treatment techniques are considered most promising. In this study for the first time, 9 different zeolites and powdered activated carbon (PAC) were tested for 18 PFAS including C-3-C-13 perfluoroalkyl carboxylates acids (PFCAs), C-4, C-6, C-8 perfluoroalkane sulfonates (PFSA), three fluorotelomer sulfonate (FTSAs), and perfluorooctane sulfonamide (FOSA) in batch sorption experiments using ultrapure and real environmental water samples. Adsorption experiments showed that zeolite beta with SAR = 25 (silica alumina ratio, SiO2/Al2O3) (99.5% n-ary sumation PFAS uptake) and SAR = 300 (99.2% n-ary sumation PFAS uptake), and mordenite with SAR = 240 (87.8% n-ary sumation PFAS uptake) were the most promising adsorbent media. Sorption of individual PFAS depended on the perfluoroalkyl chain length, functional group and molecule size. Overall, AgY390 and AgY760 silver (Ag) functionalized zeolites (76.4% and 78.3% n-ary sumation PFAS uptake respectively) showed better uptake capacity for PFAS compared to the as-synthetized Y390 and Y760 (68.6% and 68.3% n-ary sumation PFAS uptake respectively), and could favor catalytic reactions in PFAS degradation. PFAS sorption to PFAS-fortified real contaminated water samples was as follows: Beta25 (99.4%) < Beta360 (97.5%) < MOR (97.1%) < Y760 (95.5%) < CHA (71.4%) (with respect to PAC 99.9%). X-ray structural data revealed that changes in unit cell parameters arise from channel distortions caused by the encapsulation of PFAS inside the zeolites cages. Thermal analyses corroborate these results and revealed degradation of the perfluoroalkyl chain and expulsion upon heating are accompanied by exothermic reactions registered in the differential thermal analysis (DTA). The features of the zeolites, including the specific surface area, pores size and distribution, SAR, temperature, presence of extraframework cations and polarity significantly affected their PFAS adsorption capacity.
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| 2. |
- Ahrens, Lutz
(författare)
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Themed issues on per- and polyfluoroalkyl substances
- 2019
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Ingår i: Environmental science: water research & technology. - : Royal Society of Chemistry (RSC). - 2053-1419 .- 2053-1400. ; 5, s. 1808-1813
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Guest editors Lutz Ahrens, Jonathan Benskin, Ian Cousins, Michelle Crimi and Christopher Higgins introduce the "Per- and polyfluoroalkyl substances (PFASs)" themed issue.
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| 3. |
- Almstrand, Robert
(författare)
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Succession of founding microbiota in an anaerobic baffled bioreactor treating low-temperature raw domestic wastewater
- 2022
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Ingår i: Environmental Science: Water Research & Technology. - : Royal Society of Chemistry (RSC). - 2053-1400 .- 2053-1419. ; 8, s. 792-806
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Tidskriftsartikel (refereegranskat)abstract
- Continuously operated pilot- and full-scale anaerobic baffled reactors (ABRs) treating low-temperature raw domestic wastewater are currently few in number but offer significant advantages. As ABRs treating domestic wastewater become more prevalent, engineers and operators face the practical challenge of effectively transferring and seeding anaerobic sludge from existing "donor" ABRs to newly constructed ABRs. Unlike activated sludge, which predominantly consists of relatively fast-growing aerobic heterotrophic bacteria, anaerobic microbiota are slower-growing and the community structure may be impacted by process disturbances during bioreactor start-up. Examining the spatiotemporal development of anaerobic microbiota after transfer can enhance understanding of start-up dynamics in engineered anaerobic bioreactor systems. To understand the impacts of sludge transfer and seeding from an existing ABR operated for 3.5 years treating raw, low-temperature domestic wastewater to a new, similarly configured ABR treating a different raw domestic wastewater stream, influent wastewater and sludge microbiota samples were withdrawn biweekly for 275 days and used to characterize changes to the microbial community structure over time in both ABRs. Results suggest that the donor ABR communities maintained relatively consistent structure over time, but the microbial communities in the receiving bioreactor experienced two apparent successional trajectories post-inoculation. The first trajectory, which lasted for similar to 120 days, showed increasing divergence between communities in the two ABRs. This trajectory was marked by lower wastewater temperatures (12-14 degrees C, with extreme lows of 8 degrees C) and numerous disturbances to the sludge blankets. A second successional trajectory, observed when wastewater temperatures increased (>16 degrees C) and disturbances were eliminated, was marked by significant increases in the relative abundance of Euryarchaeota, especially Methanosaeta ("Methanothrix"), and increasing convergence of microbial communities in complementary donor and receiving bioreactor compartments. Further, the relative abundance of founding microbial community members significantly decreased during the first successional trajectory but significantly increased, or rebounded, during the second successional trajectory. The results of this study indicate that an anaerobic sludge inoculum can be effectively transferred from a long-running ABR treating raw, low-temperature domestic wastewater to a new ABR, and that similar performance can be achieved despite differing environmental conditions and disturbances to the sludge blanket microbial communities during start-up of the new ABR.
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| 4. |
- Andersson, Anna, et al.
(författare)
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Molecular changes among non-volatile disinfection by-products between drinking water treatment and consumer taps
- 2021
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Ingår i: Environmental Science. - : Royal Society of Chemistry. - 2053-1400 .- 2053-1419. ; 7:12, s. 2335-2345
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Tidskriftsartikel (refereegranskat)abstract
- The formation of disinfection by-products (DBPs) during drinking water treatment has been associated with various health concerns but the total DBP exposure is still unknown. In this study, molecular level non-target analysis by Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) was used to study non-volatile DBPs, and how their composition changes during water distribution in four drinking water treatment plants (DWTPs) in Sweden using different types of raw water and disinfection processes. The largest portion of tap water DBP compositions were detected also at the DWTPs, highlighting that these DBP formulae were rather stable and contribute to human DBP exposure. Yet the number of detected DBPs decreased 14-48% between drinking water treatment and consumer taps in the three plants in which no mixing of water from other DWTPs in the distribution system occurred showing active DBP processing in the water distribution network. While considerable amounts of bromine-containing DBPs were detected upon chemical disinfection in some DWTPs, few of them were detected in the tap water samples, likely due to debromination by hydrolytic reactions. The overall fewer non-volatile DBPs detected in tap waters, along with changed distribution among chlorine and bromine DBPs, demonstrate that DBP mixtures are highly dynamic and that DBP measurements at DWTPs do not adequately reflect exposure at the point-of-use. Clearly, more knowledge about changes of DBP mixtures through the distribution system is needed to improve DBP exposure assessments.
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| 5. |
- 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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| 6. |
- 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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| 7. |
- Aqeel, Hussain, et al.
(författare)
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Drivers of bioaggregation from flocs to biofilms and granular sludge
- 2019
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Ingår i: Environmental Science: Water Research and Technology. - : Royal Society of Chemistry (RSC). - 2053-1419 .- 2053-1400. ; 5:12, s. 2072-2089
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Forskningsöversikt (refereegranskat)abstract
- Microorganisms in natural and engineered environments interact with surfaces and form aggregates consisting of cells and an extracellular matrix. The design of the process and appropriate operational conditions drive the formation of these biofilms, flocs, and granular structures. The application of granular sludge technologies for nutrient removal is relatively new. Although research and practice benefit from several decades of investigation of biofilm and anaerobic granular sludge systems, a thorough understanding of factors affecting granulation is only beginning to emerge from bench, pilot, and full-scale investigations. Challenges intrinsic to maintaining granular and biofilm structures include management of resistance to substrate transport, establishment of targeted microbial niches, role of extracellular polymeric substances, and impacts of toxic compounds, among others. There is increasing recognition of the potential value of hybrid process configurations that optimize interactions between flocs, granules, and/or biofilm features for process enhancement and robustness. While these structures appear distinct, it is not uncommon to find a mixture of these structures present in a single system and dynamics leading to a transition from one structure to another. The transitions are dependent on changes in the microbial community and properties of the extracellular matrix. This review focuses on the drivers affecting formation and stability of flocs, biofilms, and granules and conditions that support integrated technologies for biological wastewater treatment.
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| 8. |
- Byrne, D. M., et al.
(författare)
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Life cycle assessment (LCA) of urban water infrastructure: emerging approaches to balance objectives and inform comprehensive decision-making
- 2017
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Ingår i: Environmental Science: Water Research and Technology. - : Royal Society of Chemistry (RSC). - 2053-1419 .- 2053-1400. ; 3:6, s. 1002-1014
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Tidskriftsartikel (refereegranskat)abstract
- Life cycle assessment (LCA) has been widely used to quantify environmental impacts associated with urban water infrastructure, including wastewater, drinking water, stormwater, and integrated urban water systems. While LCA is applicable for the estimation of global environmental impacts, decision-makers must balance these impacts with local, often regulated, environmental and public health objectives. To characterize the state of the art for the use of LCA for urban water infrastructure, a thorough literature review was conducted of papers that applied LCA to wastewater (173 papers), drinking water (44 papers), stormwater (17 papers), and integrated urban water (22 papers) systems. Analyses revealed current preferences for functional unit basis (e.g., volume for wastewater), system boundaries (e.g., focus on operation), and impact assessment methodology (CML, ReCiPe, and Eco-Indicator). Based on these findings, LCA methodological recommendations for urban water infrastructure are made, and emerging opportunities to balance objectives and inform comprehensive decision-making are discussed. Critical opportunities include the integration of spatial considerations (e.g., spatialized characterization factors), water quantity (e.g., water quantity indicators), public health (e.g., integration with risk assessment), economic and social assessments (e.g., life cycle costing and social LCA), along with prioritization of continuous stakeholder engagement. Finally, research and development needs specific to the use of LCA for urban water infrastructure (e.g., development of new indicators coupled with case studies) are prioritized.
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| 9. |
- Cascone, C., et al.
(författare)
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AbspectroscoPY, a Python toolbox for absorbance-based sensor data in water quality monitoring
- 2022
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Ingår i: Environmental Science. - : Royal Society of Chemistry (RSC). - 2053-1400 .- 2053-1419. ; 8:4, s. 836-848
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Tidskriftsartikel (refereegranskat)abstract
- The long-term trend of increasing natural organic matter (NOM) in boreal and north European surface waters represents an economic and environmental challenge for drinking water treatment plants (DWTPs). High-frequency measurements from absorbance-based online spectrophotometers are often used in modern DWTPs to measure the chromophoric fraction of dissolved organic matter (CDOM) over time. These data contain valuable information that can be used to optimise NOM removal at various stages of treatment and/or diagnose the causes of underperformance at the DWTP. However, automated monitoring systems generate large datasets that need careful preprocessing, followed by variable selection and signal processing before interpretation. In this work we introduce AbspectroscoPY (“Absorbance spectroscopic analysis in Python”), a Python toolbox for processing time-series datasets collected by in situ spectrophotometers. The toolbox addresses some of the main challenges in data preprocessing by handling duplicates, systematic time shifts, baseline corrections and outliers. It contains automated functions to compute a range of spectral metrics for the time-series data, including absorbance ratios, exponential fits, slope ratios and spectral slope curves. To demonstrate its utility, AbspectroscoPY was applied to 15-month datasets from three online spectrophotometers in a drinking water treatment plant. Despite only small variations in surface water quality over the time period, variability in the spectrophotometric profiles of treated water could be identified, quantified and related to lake turnover or operational changes in the DWTP. This toolbox represents a step toward automated early warning systems for detecting and responding to potential threats to treatment performance caused by rapid changes in incoming water quality.
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| 10. |
- Ekholm, Jennifer, 1992, et al.
(författare)
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Full-scale aerobic granular sludge for municipal wastewater treatment - granule formation, microbial succession, and process performance
- 2022
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Ingår i: Environmental Science: Water Research and Technology. - : Royal Society of Chemistry (RSC). - 2053-1419 .- 2053-1400. ; 8:12, s. 3138-3154
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Tidskriftsartikel (refereegranskat)abstract
- Aerobic granular sludge (AGS) plants have gained growing interest and application due to their low energy demand, small footprint, and low operational costs. However, the fulfilment of strict discharge limits for nitrogen and phosphorus, vast seasonal temperature variations, and large peaks in influent flows may pose challenges to the implementation of AGS. Moreover, the knowledge about microbial community assembly and process performance under varying environmental conditions in full-scale reactors is still limited. In this study, the first implementation of the AGS process in the Nordic countries was assessed. In two full-scale AGS reactors with different seeding sludges, the start-up was associated with rapid changes in microbial community composition in both, but only successful granulation in one. As a consequence, the non-granulated reactor was eventually reseeded with biomass from the better granulated reactor. This resulted in a convergence of the microbial communities in the two reactors with the maintenance of stable sludge concentrations (6-8 g L-1) with large granules (50-80% with diameter >2 mm) and fast settling of biomass (SVI30/SVI10 of 0.9-1). Immigration from the influent wastewater was a minor factor affecting the microbial community once the granules had formed, while the seasonal variations in environmental factors were identified as important. Key guilds of AOB (Nitrosomonas), NOB (mainly Ca. Nitrotoga), PAOs (mainly Tetrasphaera), and GAOs (mainly Ca. Competibacter) varied considerably in abundance throughout the study period. After 15 months, stable organic matter, nitrogen, and phosphorus removal were attained with low effluent concentrations. During the start-up, the BOD7/N ratio, influent flow, and temperature were important factors influencing the performance of the AGS.
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