| 1. |
- Al-Abri, M., et al.
(författare)
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Chlorination disadvantages and alternative routes for biofouling control in reverse osmosis desalination
- 2019
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Ingår i: npj Clean Water. - : Nature Research. - 2059-7037. ; 2:1
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Tidskriftsartikel (refereegranskat)abstract
- With an ever-increasing human population, access to clean water for human use is a growing concern across the world. Seawater desalination to produce usable water is essential to meet future clean water demand. Desalination processes, such as reverse osmosis and multi-stage flash have been implemented worldwide. Reverse osmosis is the most effective technology, which uses a semipermeable membrane to produce clean water under an applied pressure. However, membrane biofouling is the main issue faced by such plants, which requires continuous cleaning or regular replacement of the membranes. Chlorination is the most commonly used disinfection process to pretreat the water to reduce biofouling. Although chlorination is widely used, it has several disadvantages, such as formation of disinfection by-products and being ineffective against some types of microbes. This review aims to discuss the adverse effect of chlorination on reverse osmosis membranes and to identify other possible alternatives of chlorination to reduce biofouling of the membranes. Reverse osmosis membrane degradation and mitigation of chlorines effects, along with newly emerging disinfection technologies, are discussed, providing insight to both academic institutions and industries for the design of improved reverse osmosis systems.
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| 2. |
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| 3. |
- Dickin, Sarah, et al.
(författare)
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Sustainable sanitation and gaps in global climate policy and financing
- 2020
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Ingår i: NPJ CLEAN WATER. - : Springer Science and Business Media LLC. - 2059-7037. ; 3:1
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Forskningsöversikt (refereegranskat)abstract
- Although sanitation systems are fundamental for human health and sustainable development, limited focus has been placed on their contributions to climate mitigation and adaptation. Climate change threatens existing systems, as well as efforts to increase services for 2.3 billion people who lack even a basic sanitation service. At the same time, the sanitation and wastewater sector directly produces emissions associated with breakdown of organic matter, and treatment processes require large energy inputs. In light of these challenges, we describe gaps in how sanitation is being addressed in mitigation and adaptation, discuss how this results in little inclusion of sanitation in climate policy and financing at the global level, and implications of these gaps for different sanitation systems and geographic regions. Finally, we describe the need for planning frameworks to facilitate integration of climate change into sanitation policy and programming. This will be critical to increasing understanding of sanitation and climate change linkages among stakeholders, and more effectively including sanitation in climate action.
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| 4. |
- Nordstrand, Johan, et al.
(författare)
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Flexible Modeling and Control of Capacitive-deionization Processes through a Linear-state-space Dynamic-Langmuir Model
- 2021
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Ingår i: npj Clean Water. - : Springer Nature. - 2059-7037. ; 4:5, s. 1-7
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Tidskriftsartikel (refereegranskat)abstract
- While black-box models such as neural networks have been powerful in many applications, direct physical modeling (white box) remains crucial in many fields where experimental data are difficult or time-consuming to obtain. Here, we demonstrate with an example from desalination by capacitive deionization (CDI), how an existing physical model could be strengthened by combining a general modeling framework with physical insights (gray box). Thus, a dynamic Langmuir (DL) model is extended to a linear-state- space DL model (LDL). Results obtained show the new LDL model could incorporate general structural and operational modes, including membrane CDI and constant-current operation. The formulation removes the need for direct measurements of detailed device properties without adding model complexity, and MATLAB code for automatically implementing the model is provided in the Supplementary Information. We conclude the new LDL model is widely applicable, offering great flexibility in calibration data, and enabling prediction over general operating modes.npj
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| 5. |
- Pullerits, Kristjan, et al.
(författare)
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Impact of UV irradiation at full scale on bacterial communities in drinking water
- 2020
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Ingår i: npj Clean Water. - : Springer Science and Business Media LLC. - 2059-7037. ; 3:1
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Tidskriftsartikel (refereegranskat)abstract
- Water in a full-scale drinking water treatment plant was irradiated with ultraviolet (UV) doses of 250, 400, and 600 J/m2, and the effect on bacterial communities investigated using 16s rRNA gene amplicon sequencing, heterotrophic plate counts (HPCs), coliform, and Escherichia coli counts. The bacteria in the irradiated water were also analyzed following storage for 6 days at 7 °C, to approximate the conditions in the distribution system. The log10 reduction of HPCs at 400 J/m2 was 0.43 ± 0.12. Phylogenetic examination, including DESeq2 analysis, showed that Actinobacteria was more resistant to UV irradiation, whereas Bacteroidetes was sensitive to UV. Phylum Proteobacteria contained monophyletic groups that were either sensitive or resistant to UV exposure. The amplicon sequence variants (ASVs) resistant to UV irradiation had a greater average GC content than the ASVs sensitive to UV, at 55% ± 1.7 (n = 19) and 49% ± 2.5 (n = 16), respectively. Families Chitinophagaceae, Pelagibacteraceae, Holophagaceae, Methylophilaceae, and Cytophagaceae decreased linearly in relative abundance, with increasing UV dose (P < 0.05, Pearson’s correlation). When irradiated water was stored, Chitinophagaceae, Comamonadaceae, and Flavobacteriaceae families decreased in relative abundance, whereas ACK-M1, Mycobacteriaceae, and Nitrosomonadaceae were increasing in relative abundance. This suggests that the impact of UV irradiation cannot only be considered directly after application but that this treatment step likely continues to influence microbial dynamics throughout the distribution system.
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| 6. |
- Rosenqvist, Tage, et al.
(författare)
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Succession of bacterial biofilm communities following removal of chloramine from a full-scale drinking water distribution system
- 2023
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Ingår i: npj Clean Water. - 2059-7037. ; 2023:6
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Tidskriftsartikel (refereegranskat)abstract
- Monochloramine is used to regulate microbial regrowth in drinking water distribution systems (DWDS) but produces carcinogenic disinfection byproducts and constitutes a source of energy for nitrifying bacteria. This study followed biofilm-dispersed microbial communities of a full-scale DWDS distributing ultrafiltered water over three years, before and after removal of monochloramine. Communities were described using flow cytometry and amplicon sequencing, including full-length 16S rRNA gene sequencing. Removal of monochloramine increased total cell counts by up to 440%. Increased abundance of heterotrophic bacteria was followed by emergence of the predatory bacteria Bdellovibrio, and a community potentially metabolizing small organic compounds replaced the nitrifying core community. No increased abundance of Mycobacterium or Legionella was observed. Co-occurrence analysis identified a network of Nitrosomonas, Nitrospira, Sphingomonas and Hyphomicrobium, suggesting that monochloramine supported this biofilm community. While some species expanded into the changed niche, no immediate biological risk to consumers was indicated within the DWDS.
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| 7. |
- Vavilapalli, Durga Sankar, et al.
(författare)
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Enhanced photocatalytic performance of a rGO-Ca2Fe2O5 nanocomposite for photodegradation of emergent pollutants
- 2024
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Ingår i: NPJ CLEAN WATER. - : NATURE PORTFOLIO. - 2059-7037. ; 7:1
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Tidskriftsartikel (refereegranskat)abstract
- In this study, a simple thermal reduction process is used to synthesize a rGO-Ca2Fe2O5 (rGO-CFO) nanocomposite, with the morphological and optical characteristics of the CFO nanomaterial being modified by the rGO incorporation. The interface between rGO nanosheets and CFO nanoparticles facilitates efficient charge separation and resulting transfer of photogenerated charge carriers across the rGO nanosheets, demonstrated from photoluminescence and Mott-Schottky tests. Compared to CFO (2.1 eV), rGO-CFO has a reduced band gap energy of 1.9 eV. As synthesized nanocomposites were initially optimized and utilized for photodegradation of organic effluent Methylene blue (MB). An addition of 5 wt% rGO to the CFO demonstrated an improved photodegradation efficiency (97%) compared to bare CFO (72%). An active species trapping experiment was used to assess the MB photodegradation mechanism. The results demonstrate that hydroxyl radicals and holes are the major active species involved in photodegradation. The optimized composition (5rGO-CFO) was further tested for degradation of Bisphenol-A and Tetracycline (antibiotic). Altogether, these investigations show that the rGO-CFO is a highly efficient photocatalyst that can be used to remediate emerging contaminants in sunlight.
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